INSIGHTS. Boeing Rotorcraft Improves Safety with Nonlinear FEA. DS Realistic Simulation Magazine. Composites Strategy Accelerates Simulation

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1 INSIGHTS 1 DS Realistic Simulation Magazine Composites Strategy Accelerates Simulation Firestone Improves Piston Durability and Performance Boeing Rotorcraft Improves Safety with Nonlinear FEA DeepSea Redefines 3D Dynamic Umbilical Modeling

2 Contents INSIGHTS June/July Inside This Issue 8 Cover Story Boeing Rotorcraft Improves Safety with Nonlinear FEA 11 Strategy Overview 14 Accelerating Composites Simulation Customer Case Study Firestone Improves Piston Durability and Performance In Each Issue Executive Letter Ushering in a New Era of Realistic Simulation (Mark Goldstein, CEO, SIMULIA) In The News DeepSea Engineering Evaluates Umbilical Design Airbus Selects Abaqus New Director of Technical Services New EL Team Leader Product & Solutions Updates New Features in Abaqus Version 6.7 Multiphysics Solutions Academic Update Harvard Student Analyzes Golf Equipment with Abaqus New Geotechnical Textbook Alliances Updates MIMICS, CATIA, and Abaqus FEA Used for 3D Foot Simulation Events AUC 2007 Recap Regional Users Meetings Webinars INSIGHTS is published by Dassault Systèmes Simulia Corp. Rising Sun MiIls 166 Valley Street Providence, RI Tel Fax info@3ds.com Editor: Tim Webb Associate Editor: Lisa Miller Contributors: Paolo Antunes et al (courtesy of Materialise), Dale Berry, Greg Brown, Karen Curtis, Jan Demone, Mark Dixon (DeepSea Engineering), Mark Goldstein, Pradipta Moulik (Firestone Industrial Products), The Parker Group, Adrian Podpirka, Frank A. Smith & Paul M. Hopkins (Boeing Rotorcraft) Graphic Designer: Todd Sabelli MAR_INS_Y07_VOL 01 The 3DS logo, SIMULIA, and Abaqus are trademarks or registered trademarks of Dassault Systèmes or its subsidiaries. Other company, product, and service names may be trademarks or service marks of their respective owners. Copyright Dassault Systèmes, 2007 Photo credits: page 8, Department of Defense, page 11, photo courtesy of Greg Brown.

3 Executive Message Ushering in a New Era for Realistic Simulation It seems like only yesterday that we announced the completion of Dassault Systèmes acquisition of ABAQUS, Inc. and the establishment of the SIMULIA brand. On that date, October 3, 2005, we promised to maintain our focus on advanced finite element analysis solutions, deliver an open platform for multiphysics simulation, and create next-generation solutions for realistic 3D simulation. As I write this letter to you, I am pleased to report that through focused planning, close interaction with our customers, and accelerated development activities, we have fully transitioned to the SIMULIA brand and delivered on our promises, as demonstrated by three major announcements: 1. The release of Abaqus Version 6.7 for Unified FEA 2. The launch of our new multiphysics platform and direct coupling capabilities 3. Our new initiative for providing Simulation Lifecycle Management (SLM) solutions Mark Goldstein CEO, SIMULIA The usability and functionality enhancements in Abaqus Version 6.7 deliver on our promise to remain focused on advanced FEA solutions, and this release is superior to any FEA product on the market. Not only are the composites, linear dynamics, and contact capabilities improved, but our development team has delivered unmatched solver performance that is capable of scaling to 128 CPUs. Through internal development as well as close working relationships with our alliance partners, our multiphysics announcement confirms our strategy for developing an open platform that allows multiple analysis types to be solved within a unified environment. This open strategy enables users to select the right solution for the specific type of problems that they are trying to solve. As we have heard from our customers, next-generation simulation solutions must not only focus on technology breakthroughs; they must also provide a means to manage processes, data, and intellectual property. As a result, we have announced our initiative for Simulation Lifecycle Management solutions. A white paper outlining our strategy is available on our website, and the first product in our SLM portfolio will be available later this year. I would be remiss if I did not mention the significance of Airbus selecting Abaqus as their preferred solution for nonlinear FEA of aircraft structures. It not only validates our strategy of making nonlinear FEA technology a key enabler for delivering realistic simulation, it confirms our continued growth at major OEMs who are committed to implementing SIMULIA solutions that provide high-fidelity correlation to the physical world. What can you do to engage with us during this exciting time in our history? I encourage you to participate in your Regional Users Meetings that are being held around the world. By attending these meetings you will learn first hand about the latest enhancements to our products as well as our future direction. You will also be able to interact with SIMULIA professionals and to provide input on your experiences and requirements. We are proud of our heritage and excited about the future of SIMULIA as we extend our product portfolio to provide you with the best solutions and support to meet your business and simulation challenges. I look forward to continuing and strengthening our relationship with you and your organization. Cordially, Mark Goldstein CEO, SIMULIA INSIGHTS June/July

4 In The News Industry Press Coverage Desktop Engineering February 2007, pp CFD s Expanding Role In an overview article about computational fluid dynamics (CFD), Contributing Editor Pamela J. Waterman describes how recent advances in both fluid flow and structural analyses are enabling MCAD users to embrace CFD capabilities across a wide range of applications. Abaqus FEA software is discussed and illustrated with an FSI graphic analyzing the effects of blood flow on a diseased artery with an aneurism. DESIGNFAX Online April 2007 Simulation Helps Produce Life-Saving Cooling Technology Argonne National Laboratory, in partnership with the University of Chicago Medical School, used Abaqus FEA software to simulate the cooling of a human kidney to examine how to slow tissue deterioration during surgery. The team created a 3D mesh model for a kidney, incorporated an equation for tissue metabolism and perfusion thermal behavior into Abaqus, and compared the simulation results with physical data. Desktop Engineering March 2007, pp. 2 5 Analyzing Air Spring Data Step-by-step graphics are a highlight of this story by Pradipta Moulik of Firestone Industrial Products. The article describes a puzzling problem of automotive air spring deformation after very low fatigue cycles. Abaqus FEA software predicted the failure and enabled engineers to revise their design for better durability and performance. See the INSIGHTS article on page 14. Aerospace Engineering (SAE) March 2007, pp Nonlinear Modeling Improves Rotorcraft Safety Simulation of the helicopter stub wing performed with Abaqus FEA helped Boeing Rotorcraft address fatigue cracking that appeared after load capacity upgrades to their CH-46E craft. Frank Smith, Lead Stress Engineer for Boeing Rotorcraft, describes the analyses used to identify the origin of the cracking and to determine an accurate method for nonlinear analysis with an acceptable run time. See the INSIGHTS cover story on page 8. NASA Tech Briefs March 2007, pp Progressive Failure Analysis of Composite Structures NASA s John Glenn Research Center authored an article on coupling micromechanics analysis code (MAC) with Abaqus FEA software to determine the behavior of composite materials and laminates at the fiber and matrix level. The multiscale FEAMAC framework circumvents the need for complex, multiaxial, anisotropic damage, and constitutive models that are required to operate on the macro scale. Composites Technology April 2007 FEA Roundup: Design, Simulation & Analysis Converge Editor-in-Chief Jeff Sloan surveys recent FEA software offerings in this roundup article and interviews Sandor Becz, SIMULIA s Aerospace Industry Solutions Manager. Becz discusses modeling and simulation of composite failure, noting that the layered nature of composites may cause damage to propagate undetected. He describes how Abaqus FEA software is designed to address a range of analytical functions with an emphasis on cycle loading, stress, and impact damage modeling. Mechanical Engineering May 2007, pages Tying Two Forces Analyzing fluid and structural interaction is getting easier, but progress still needs to be made on making it faster, reports Associate Editor Jean Thilmany in this industry review of fluid structure interaction (FSI). The article quotes SIMULIA Director of Industry Solutions, Dale Berry, who describes how SIMULIA and CD-Adapco have joined forces to combine Abaqus and STAR-CD to enable engineers to solve FSI problems within their preferred FEA and CFD software. See the INSIGHTS article on page 17. To read the full stories highlighted here, please visit To share your success story, send an with a brief description of your application to info@simulia.com. INSIGHTS June/July

5 In The News DeepSea Engineering Applies Unique Process to Evaluate Umbilical Design In an article for Offshore Magazine, Mark Dixon of DeepSea Engineering outlines a novel approach to accurately model subsea umbilical behavior to diminish the likelihood of failure. Umbilical failure in off-shore exploration can impact flow assurance, be costly to repair, and potentially halt operations. Measuring friction and load transfer in an umbilical using Abaqus FEA. more robust and physically accurate analyses. According to Dixon, traditional simulation practices have oversimplified umbilicals by failing to take into account their complex structure, which consists of wound cables and tubes. Deepsea Engineering developed a proprietary 3D analysis process leveraging Abaqus to perform A global model of the umbilical system was constructed using Orcaflex (an industry-specific software from Orcina). Force and curvature time histories of the components were generated and used as input to the FEA models. A 3D length of the umbilical was modeled, paying specific attention to contact points, friction stress, and bending stress, which vary over time and position. Cross-section asymmetry ignored in simplified analytical assessments was also taken into account. This integrated 3D simulation process enables DeepSea engineers to determine an umbilical system s deepwater limit, compare designs from various suppliers, and improve decision making about installation of the umbilicals in harsh, deep-water environments. View the complete article from Offshore Magazine at: New Director of Worldwide Technical Services Mike Ricci is the new Director of Worldwide Technical Services for SIMULIA. Mike is focused on coordinating our industry-leading consulting services to ensure that we provide a consistent and complete line of innovative services in all parts of the world. Mike will work to enhance communication and leverage expertise across all of our regions. SIMULIA has a significant number of engineering professionals located around the world, stated Mike. I am very pleased to be part of such a talented team that has helped hundreds of customers optimize product performance, integrate time-saving process strategies, and develop more robust simulation methods. Airbus Selects Abaqus for Nonlinear FEA of Aircraft Structures In May 2007, Airbus announced that it has chosen the Abaqus Finite Element Analysis (FEA) software suite as its preferred solution for static nonlinear FEA. This decision came as a result of an extensive benchmark of several FEA codes. Abaqus has already been successfully applied to the A380 aircraft program for structural virtual testing, representing a first step in what is to develop into a longer-term collaborative relationship. This announcement reinforces the fact that the world s leading companies see nonlinear FEA technology as a key enabler for delivering realistic simulations with high-fidelity correlation to the physical world, stated Ken Short, SIMULIA s Vice President of Strategy & Marketing. According to a multiyear corporate agreement, SIMULIA will provide Abaqus software and services to Airbus sites located in Toulouse (France), Filton (U.K.), Hamburg/Bremen (Germany), and Getafe (Spain). Airbus will use Abaqus to support its development of advanced virtual testing methods. New Eulerian-Lagrangian Solver Team Leader Brad Maker is the new leader of SIMULIA s Eulerian-Lagrangian (EL) technology team. This technology provides users with the ability to simulate fluid-structure interaction (FSI) problems without relying on the coupling of third-party software products. The EL multiphysics capability will be available in the fall of 2007 in the Abaqus Version 6.7 Extended Functionality release. The Abaqus Unified FEA suite is already the tool of choice for simulations involving large nonlinear deformation, said Brad. I am excited to lead such a dedicated group of engineers to extend EL simulation capabilities to problems such as gas-flow inflated airbags, tire hydroplaning, wave loading, cosmetic dispensing, fuel tank sloshing, and high-velocity impact and penetration. Brad has been working in FEA for more than 25 years, with specific interest in high-performance computing, computational mechanics, and software development. He came to SIMULIA three years ago from Livermore Software Technology Corporation (LSTC) where he was a Senior Software Developer. Before that Brad was a Research Consultant for orthopedic biomechanics projects with the University of Utah and a Lead Software Developer for the Lawrence Livermore National Laboratory s Methods Development Group. Brad has his BSE, MSE, and PhD in Aerospace Engineering (Structural Mechanics) from The University of Michigan. Mike has more than 20 years of industry experience, most recently working as a Principal Consultant at UGS and, prior to that, serving as the VP of Professional Services at Proficiency. Mike has a Bachelors and Masters in Mechanical Engineering from Northeastern University. INSIGHTS June/July 2007

6 Product & Solutions Updates Abaqus Version 6.7 for Unified FEA Innovative Functionality and Enhanced Distributed Computing Performance Expands Simulation Capabilities for Real-World Applications To meet our customers increasing demand for realistic simulation solutions, Abaqus Version 6.7 delivers new industryleading capabilities for high-performance computing, enhancements for linear dynamics, and new capabilities for composites modeling. The latest release also includes improvements to the user interface for model building, results output, and visualization; a new associative interface for CATIA V5; and improvements to elements and general analysis capabilities. High-Performance Computing One of the most significant achievements in Abaqus Version 6.7 is the improvement made to our distributed memory parallel (DMP) direct sparse solver technology. Memory use is significantly reduced when running on 4 or more compute nodes, and the solver is scalable from small to large models. In a tire benchmark model consisting of 250,000 degrees of freedom, clock speed was improved by 9 running on 16 CPUs compared to 1 CPU. In a large model of nearly 10 million DOFs, the solver was able to scale to 128 CPUs, enabling the simulation to run in 4 hours compared to 3 days on 4 CPUs. The SIMULIA team responsible for this development received a DS Innovation Forward Award, which Dassault Systèmes gives to select individuals or teams making significant achievements in research and development. Linear Dynamics The linear dynamics architecture has been extended to support mode-based transient dynamics, material and element damping, and dynamic substructuring. These capabilities are fully integrated with the proven nonlinear capabilities in Abaqus, enabling engineers to share model data and results seamlessly between multidisciplinary workgroups. In an 8 million DOF structuralacoustic benchmark model, wall-clock speed was improved from 3.2 hours to 1.1 hours using the AMS capability. These improvements provide significant benefits to all industry users, but they are particularly useful for automotive manufacturers. By providing complete performance attribute coverage within a unified simulation environment, engineers are able to perform a complete range of analyses including, structural integrity, powertrain durability, noise and vibration, crashworthiness, occupant safety, and more. The DMP direct sparse solver demonstrates impressive scaling. Detailed simulations, with millions of degrees of freedom such as this engine block, can now be run in a few hours rather than a few days. New Capabilities for Composites Modeling Modeling composite laminates has traditionally been time-consuming and errorprone. A new composite lay-up modeler provides an intuitive user experience for accurately creating, reviewing, and interpreting composites plies and analysis results. This feature eliminates the need for manual layer number input and enables users to evaluate detailed ply-based results using ply stack plots and throughthickness X Y plots. With the new highperformance linear dynamics capabilities, the frequency response of an 800,000 degree of freedom body-in-white model with material damping is completed more than 300 times faster than before. SIMULIA is delivering several important enhancements to their Abaqus FEA software that we expect will greatly improve overall productivity at Scania, stated Martin Edberg, head of chassis simulations, Scania CV AB. We are particularly impressed with the new high-performance linear dynamics functionality in Abaqus Version 6.7. Summary Abaqus Version 6.7 contains hundreds of improvements and addresses many customer requests for enhancements. Usability and productivity is a major focus, and the new version delivers improvements such as customizable toolbars, a 3D compass, and 3D XML-export. The automatic contact detection feature not only saves time, but it also assists in defining contact in complex geometry. The new associative interface for CATIA V5 streamlines synchronizing CAD models with Abaqus analyses. We remain focused on developing innovative analysis technology that enables engineers to tackle new problems such as the analysis of lead-free solder and laminated composites. As computing power increases, SIMULIA will be on the forefront of developing scalable solutions that enable users to add more realistic details to their simulations. We look forward to working closely with you to deliver more innovative advancements in future releases. (Continued at top of page 7) 6 INSIGHTS June/July

7 Product & Solutions Updates New Features & Enhancements in Abaqus Version 6.7 Usability New GUI-driven composite lay-up manager Automatic contact detection Associative interfaces for CATIA V5 and Pro/ENGINEER The graphical user interface provides dockable toolbars and a viewport compass Analysis Improved integration between implicit and explicit procedures Expanded element library with greater flexibility for meshing geometry Material library enhancements including an isotropic hardening model for crushable foam, a composite damage model, and structural damping Adaptive stabilization to adjust the damping factor based on convergence history Performance & Visualization Improved scalability on compute clusters New high-performance framework for mode-based linear dynamics and structural acoustics Enhanced X Y plotting capabilities 3D XML to provide a lightweight means to output and share results Learn more about Abaqus Version 6.7 through our web-based training at: The new associative interface for CATIA V5 enables CAD and FEA assemblies to be synchronized for seamless update of models with geometric changes while retaining analysis attributes. SIMULIA Multiphysics Solutions Coupled physics analyses are in demand as manufacturers across industries seek realworld insights into the complex physical behavior of their products and processes. Our SIMULIA multiphysics solutions enable simulation experts to increase the fidelity of their analyses and to take advantage of faster processing speeds and new materials. We not only provide a platform for multiphysics simulation, we also offer multiphysics solutions targeted at important applications in multiple industries. Abaqus Multiphysics Multiphysics technology has been a part of Abaqus from the beginning. Starting with Abaqus Version 2 (in 1979), Abaqus/Aqua provides the capability to simulate hydrodynamic wave loading on flexible structures for offshore pipelines. Through the years, additional capabilities have been added such as thermal, electrical, and acoustics to name a few. From the same model, element library, material data, and load history, an Abaqus FEA model can easily include additional physics interactions. No extra tools, interfaces, or simulation methodology are required. Direct Coupling Interface The new SIMULIA direct coupling interface is a key component of our multiphysics platform. It enables partner products or customer-developed software codes to be coupled with Abaqus without the need for third-party interfaces. Currently, the coupling between Abaqus and AcuSolve (from ACUSIM Software) is actively supported and qualified. The number of direct coupling co-simulation partnerships is growing steadily. Independent Code-Coupling The SIMULIA multiphysics platform also supports independent code-coupling solutions, allowing customers to utilize the best solution for their problem. Our support for MpCCI from Fraunhofer-SCAI is an example of a commonly used solution. Customers around the world use MpCCI to couple Abaqus to STAR-CD and FLUENT for fluid-structure interaction (FSI) analysis. Extended Capabilities Our Eulerian-Lagrangian (EL) approach in Abaqus Version 6.7-EF will allow engineers and scientists to simulate a select class of FSI problems. The new EL capability will enable manufacturers and researchers in all industries to use the full power of the Abaqus solver to simultaneously determine the behavior of structures and fluids in a single model without the need to couple multiple codes. Hydroplaning analysis of a passenger car tire using the Eulerian-Lagrangian approach. This capability solves the fluid-structure interaction (FSI) simultaneously within Abaqus Unified FEA. Summary Multiphysics is a challenging, yet rapidly evolving, area of simulation where it is clear that one size does not fit all requirements. The SIMULIA approach is to provide an open, flexible platform so that the right software can be coupled together for the specific problem being studied. This open approach allows our customers to choose the most effective tools to implement a best-in-class solution for their multiphysics simulations. INSIGHTS June/July

8 Cover Story Nonlinear Modeling Improves Rotorcraft Safety By Frank A. Smith Jr., Lead Stress Engineer, Boeing Rotorcraft, and Paul M. Hopkins, Stress Analyst, Boeing Rotorcraft As part of the mission of the Structural Technology and Prototyping group, Boeing Rotorcraft engineers are pursuing greater uniform margins of safety for aircraft load capacity. They set an important benchmark in 2003 when they simulated fatigue-causing loads on a CH-46E helicopter and defined an improved, efficient methodology for nonlinear finite element analysis (FEA). Boeing began work on the CH-46E in the 1980s, upgrading it to include a larger stubwing that accommodates a bigger fuel tank. The stub-wing also houses the landing gear and other equipment. Over time, some of the upgraded helicopters developed fatigue cracking at the attachment locations for the stub-wings, both in the wing fittings and on the airframe nearby. To determine the cause of the cracking, the Navy asked Boeing to analyze the CH-46E, focusing on the stubwing and the area of fuselage around it. Stress analysts at Boeing had made a business case for purchasing new computing resources that could perform exactly this sort of analysis. With advanced hardware that could run the latest generation of nonlinear stress analyses, the engineers could perform a post-buckled simulation of a known condition that occurred in the CH-46E at field-determined load levels. 8 INSIGHTS June/July

9 Cover Story Our use of nonlinear internal loads models is just the first step in an industry-wide move to FEA-based stress analysis of every load-bearing part. Frank Smith, Boeing Rotorcraft Shown is a meshed model of a Boeing CH-46E. The areas of interest on the stub-wings and fuselage are meshed in greater detail for more accuracy. The Navy provided Boeing with a complete model of the CH-46E meshed with roughly one finite element per skin bay height. (A skin bay is a unit of airframe construction bounded on four sides by frames and stringers or longerons.) For a more-accurate local analysis, Boeing engineers refined the mesh for the fuselage around the stub-wing using a one-inch mesh. They used a finer quarter-inch mesh in the stub-wing interface region, and they solid meshed (as opposed to shell meshed) the stub-wing fittings, where the main bolts attach the stub-wing to the fuselage, in even greater detail to capture the stress distribution through the fittings. Simulation of the entire helicopter was performed with Abaqus FEA software with various load configurations, such as landing and vibratory loads, bolt pre-load at the stub-wing fittings, and rotor hub loads during flight maneuvers. The engineers first performed a linear static analysis, then three separate static nonlinear analyses with: dampening from dashpot elements, dashpots and geometric imperfections derived from a buckling analysis, and dashpots and geometric imperfections derived from a linear static analysis. The engineers compared all four analyses based on strain energy, deformations, buckling shapes, and run times. To obtain physical data for comparison with the analyses, the Navy and Boeing jointly performed a CH-46E test flight with strain gauges. The engineers were initially concerned that differences between the test flight and the modeling assumptions might prevent a meaningful correlation. For instance, the physical data came from a level flight, but the aircraft was analyzed in hover condition because level flight was not considered to be a critical condition to run. Other differences between the test flight and the simulation included the change in mass as fuel was spent during flight, and the decision not to model the stub-wing fairings. Finally, stresses were fairly low during level flight, making the test results more susceptible to fluctuations in gauge data. In the end, the differences were not significant, and the level flight loads were close enough to hover loads. There was good correlation between all four analyses and the test gauge stress data. As expected, the linear static analysis did not show the degree of deformation and buckling modes that the nonlinear methods predicted. All three nonlinear static analyses produced strongly similar deformed shapes and magnitudes that closely approximated the test flight data. Review of the analyses indicated that running a nonlinear static analysis without geometric imperfections was most efficient. The engineers learned that including geometric imperfections in (Story continued on page 10) INSIGHTS June/July 2007

10 Cover Story (a) (b) (c) (d) (a) Linear static analysis did not predict the same degree of deformation and buckling that all three nonlinear analyses did. (b) A static non linear analysis with damping by dashpot elements proved to be the most efficient of the nonlinear simulations. (c, d) Adding geometric imperfections to static nonlinear analyses did not significantly improve simulation accuracy, and it increased run times by roughly 60 percent. the model did not significantly improve accuracy but increased analysis run time by approximately 60 percent. By using the data obtained from these analyses, Boeing engineers were able to identify the cause of fatigue cracking on the CH-46E helicopter stub-wing. They also determined an accurate method for nonlinear analysis with an acceptable run time. Frank A. Smith, Lead Stress Engineer, Boeing Rotorcraft Paul M. Hopkins, Stress Engineer, Boeing Rotorcraft Frank Smith co-authored this article with Paul Hopkins. Paul has worked at Boeing for two years. He received his B.S. in Architectural and Civil Engineering from Drexel University in 2000 and his M.S. in Civil Engineering from Arizona State University in Paul is working in the Dynamic Components Rotors Group using Abaqus for analysis of new composite tail rotor blade and rotor components. Frank has been with Boeing since 1997 and is a lead stress analyst for the Philadelphia Rotorcraft division. During that ten-year period, he has seen enormous advances in FEA. When I started, we made relatively simple internal loads models and performed hand analyses by extracting forces from the model and making closed-form classical calculations on a spreadsheet or with in-house computer software, Frank says. The first server that I worked with here had only two CPUs. Now we use much more detailed FEA including Abaqus models, and the latest analysis server has 120 CPUs. The subject of this case study, creating and assessing an efficient nonlinear static analysis of the CH-46E, is typical of Frank s duties at Boeing. He also plans and implements software and hardware resources that support advanced FEA in the Structural Technology and Prototyping group of Boeing Rotorcraft. According to Frank, the changes during the past decade at Boeing parallel the future of FEA in aerospace. He predicts a dramatic increase in the use of detailed FEA for both internal loads modeling and stress sizing of parts for aircraft. At present the majority of aircraft parts are still analyzed by classical methods, he says. Our use of nonlinear internal loads models is just the first step in an industry-wide move to FEA-based stress analysis of every load-bearing part. I believe it s inevitable, and the business and quality benefits will be huge INSIGHTS June/July

11 Composites Strategy SIMULIA Strategy Accelerates Composites Simulation By Dale Berry, Director, Technical Marketing SIMULIA, Dassault Systèmes Abaqus FEA software includes specialized modeling and analysis capabilities for important and unique performance characteristics of composites such as various impact, fracture, and failure modes. The latest release, Abaqus Version 6.7, provides additional tools to streamline the modeling and simulation of composite structures. Since laminated composites have a high strength-to-weight ratio and offer the potential for creating large, integrated structures, designers and analysts are working together to prove out and refine product designs to fully utilize the unique advantages of composites. However, composites are seldom simple, and neither is their analysis. As these materials gain wider use, the complexity of their part designs and manufacturing is increasing along with the need for accurate strength and failure prediction. At SIMULIA, we have responded to our customers needs by creating modeling and analysis capabilities within the Abaqus Unified FEA software suite specifically for composites. (Story continued on page 12) INSIGHTS June/July

12 Composites Strategy Advances in Usability Modeling composite laminates has traditionally been time-consuming and errorprone. Abaqus Version 6.7 provides a new composite lay-up modeler that automates formerly manual operations in pre- and posptrocessing. Abaqus provides an intuitive user experience for accurately creating, reviewing, and interpreting composite ply definitions, meshes, and analysis results. This feature eliminates the need for manual layer number input and enables users to evaluate detailed ply-based results using ply stack plots and through thickness X-Y plots. The Abaqus composites modeling capabilities can be extended through the use of a third-party plug-in from Simulayt Limited. Their new product Composites Modeler for Abaqus/CAE complements the powerful new ply modeling features in Abaqus/CAE by providing proven fiber simulation capabilities and advanced model building all seamlessly integrated. Users can perform accurate fiber modeling and create layups directly on parts in Abaqus/CAE, or they can import layup files that have been previously created in other applications that also use Simulayt s ply modeling technology. Simulation of damage in a laminated composite plate after high-speed impact by a steel ball. Innovative Capabilities Abaqus enables users to accurately simulate the behavior of composites using linear and nonlinear FEA as well as coupled multiphysics. The software is capable of manipulating the large volumes of data that define composite laminates, allowing users to model in great detail the loads, impacts, and potential failure modes of composite products that most concern part designers today. For example, composite parts on aircraft may be subjected to different types of impacts. High-velocity impacts, such as bird strikes, can cause immediate and extensive damage. A designer must make sure that such impacts, while potentially catastrophic, are survivable. With Abaqus, analysts can model the impact as a static load, or they can simulate it as a dynamic event that unfolds step-by-step, capturing any buckling, contact, damage, or deformation resulting from the impact. Barely Visible Impact Damage (BVID) is an impact event that is important to aerospace designers as well. If, for instance, a maintenance technician drops a tool on a wing surface, the visible damage might only be a small chip. Underneath the surface, the impact may generate unseen material failure in the form of fiber breakage or matrix cracking that radiates through the underlying plies. This behavior could significantly weaken the part, causing early failure. Abaqus enables analysts and designers to simulate both the impact and the effects of the impact on part strength. These simulations help analysts to identify areas of the laminate that call for additional reinforcement. Another important condition to examine is the debonding of the composite laminate. Debonding has a number of causes, from imperfections created during lay-up and curing, to loads and impacts on the completed part. Debonding can lead to the delamination of plies. Abaqus includes special tools called cohesive elements that model the behavior of initially bonded ply interfaces and can be used with interlaminar loads to simulate debonding, deformation and buckling, and delamination. The results of debonding/delamination analyses can Abaqus Version 6.7 provides a ply lay-up modeler to streamline the process of defining and managing composite plies. 12 INSIGHTS June/July

13 Composites Strategy form the basis for assessing whether a part will have enough residual strength to perform after it has begun to delaminate. Delamination modeling capabilities are useful for simulating progressive failure from a fracture. Unlike metals, which often exhibit plasticity before failure, the main failure mechanism of a composite part is brittle fracture. Over time, fracture can initiate as a crack in the material. Abaqus can model the separation of bonded surfaces from an initial point of damage and define any resulting crack for further analysis. The Virtual Crack Closure Technique (VCCT) is a well-known method of analysis that engineers use to identify the load at which the crack begins to grow. Crack growth simulation was once a slow, multistep process where analysts simulated and extended cracks manually by remodeling and remeshing at each step of crack growth. However, VCCT for Abaqus, based on technology developed by and licensed from Boeing, is a special add-on that automates this process and allows the mechanical response of the loaded structure to include crack growth as well as fracture and failure in laminated composites. Abaqus builds VCCT on top of its core analysis capabilities, providing analysts with great flexibility to simulate a range of complex behavior, including postbuckling delamination. Simulation, using VCCT for Abaqus, of buckling and debonding of composites on an aircraft skin-stringer panel. Summary Our customers requirements for composites modeling and simulation technology extends across all industries from aerospace and automotive to construction, consumer products, and even medical and dental implants. We are dedicated to continuing to enhance the Abaqus Unified FEA product suite to handle the most complex composites analyses accurately and efficiently. Stress contours in a composite bicycle frame and rim during impact with a road obstruction. The new features in Abaqus enables individual composite layers to be assessed for damage to both fiber and matrix. Dale Berry Director of Technical Marketing, SIMULIA Dale Berry has worked with us since 1988 in various capacities within our sales, product management, and marketing teams. He has extensive knowledge of Abaqus Unified FEA and created the original technology that led to fluid cavities in Abaqus. Through his work with our Fracture Customer Review Team (FCRT) and Abaqus Virtual Crack Closure Technique (VCCT), Dale is also responsible for driving our successful fracture strategy. Currently Dale is guiding our technical solution strategies in the composites, aerospace, automotive, turbomachinery, and electronics industries. His technical knowledge coupled with his understanding of specific challenges across a wide array of industries gives him the perspective and expertise to map our solutions to current and prospective client requirements. INSIGHTS June/July

14 Customer Case Study Air Spring Analysis at Firestone Strong Analysis Workflows Support FEA Problem Solving with Abaqus By Pradipta Moulik, Engineering Manager, Core Technology, Firestone Industrial Products Firestone Industrial Products Company, based in Indianapolis, Indiana, is one of the world s foremost manufacturers of air suspension technology for the transportation industry. Since 1938, when we patented the first rubber air spring, our company has continued to engineer innovative air spring systems for automotive, trucking, offroad, and rail applications. In automobiles, air springs improve ride and handling by providing a cushion of air between the wheels and the vehicle frame. The spring basically consists of an airfilled rubber cord structure that rolls up and down over a plastic or steel piston. As the vehicle travels over the roadway, the spring undergoes jounce and rebound motion, absorbing energy from the wheels. At Firestone, we rely on a sophisticated array of test equipment and FEA tools to support the design of new air springs. In a recent project, our Abaqus simulation software helped us understand why an automotive air spring piston failed during prototype testing after very low fatigue cycles. To meet our customer requirements, engineers had made a slight modification to a prototype air spring piston profile, built a new prototype, and submitted it for testing. As Figure 1 shows, the prototype buckled and cracked. The failure was unexpected, as we had thoroughly analyzed a prior design that was very similar, and the stresses were within the limits. With a cracked prototype in hand, we had to get to the bottom of the problem. Figure 1: During development of an automotive air spring prototype, physical tests showed deformation after very low fatigue cycles. Note the cracked piston at right. The material is glass-filled nylon. Figure 2: View of the prototype piston design. Firestone engineers used Abaqus software to analyze the prototype and determine why it failed during testing. Figure 3: The first step in the analysis was to model the piston in 2D axisymmetric profile. The blue arrows (left) show where loads were applied to the 2D meshed model. The analysis results (right), show only minor stress around the top lip of the piston. Based on the 2D contour plot, it appeared that the piston would withstand operational loads. 14 INSIGHTS June/July

15 Customer Case Study Using Abaqus, a 2D axisymmetric analysis of the piston profile was performed as shown in Figure 3. At operating loads, the results showed some minor stress around the lip of the piston where it fastens to the rubber cord structure. These stress results mirrored those we had obtained for the prior design and suggested that the piston should have performed correctly. A 3D analysis was performed to further investigate the failure. The 3D analysis results in Figure 4 also indicated stress around the top lip of the piston only. The stress contour plot did not predict anything close to the distortion we observed in the prototype test, and the analysis ran to completion without a hitch. The question remained. Why did the piston buckle in the test? The answer to the question lay in special diagnostics generated by Abaqus while it runs. When checking these diagnostics, the evidence of buckling was clear. Several warning notices highlighted in red indicated that the system matrix had four negative eigenvalues and that a buckling load may have been exceeded. Abaqus contains these specialized diagnostic messages specifically to help engineers conduct complex analyses, such as those required for air spring design. It is not uncommon for us to observe negative eigenvalues during simulation of air springs because we use hydrostatic fluid elements in Abaqus to model the air that compresses inside the device. Negative eigenvalues are sometimes associated with the order in which Figure 7: In a subsequent design, Firestone engineers added ribs, which increased the piston s ability to withstand buckling. the software solves equations. They do not always indicate an unstable system. In this case, however, the diagnostics messages about four negative eigenvalues bore out in the physical test results. Our next step was to perform a modal analysis to verify the four buckling modes. We could immediately see that the buckling modes in Abaqus predicted the prototype failure as indicated in Figure 5. Postbuckling analysis in Abaqus made the case even clearer. A useful feature in the software, called the Riks algorithm, allowed us to step through a static nonlinear analysis and predict the displacement visualized in Figure 6. With these results in hand, our air spring engineers were able to determine how to revise the piston design for better durability and performance. Analysis of a subsequent design shown in Figure 7 indicated that ribs added to the piston greatly improved its ability to withstand buckling loads. At Firestone, this project furthered our appreciation for developing good analysis workflows with Abaqus. Analysis teams in general may rely too much on stress contour plots for results. We recommend always consulting all diagnostic output in addition to the contour plot. When used together, they help avoid unnecessary, expensive cycles of trial-and-error prototype testing. Pradipta Moulik Engineering Manager, Core Technology, Firestone Industrial Products Pradipta has been with Firestone Industrial Products Company for more than 11 years. His work involves FEA, Rubber Compound Development, and Advanced Product Research. Pradipta received his PhD in engineering from the Purdue School of Aeronautics and Astronautics. Figure 4: To further investigate the piston failure, Firestone performed a 3D analysis. The analysis ran to completion, and the 3D stress contour plot (right) did not indicate any major problems. However, diagnostic messages in Abaqus flagged a warning that a buckling load may have been exceeded. Figure 5: Firestone engineers then performed a modal analysis of the piston, slowly increasing the pressure to observe how the structure deformed. Several buckling modes predicted the deformation observed during testing, when the piston cracked. Figure 6: During post-buckling analysis, Abaqus predicted major displacement to the piston at a pressure associated with the jounce condition. INSIGHTS June/July

16 Academic Update Harvard Student Analyzes Golf Equipment with Abaqus With a typical driver costing upwards of $400, golf equipment is big business, and the need to outperform the competition is a serious matter. Within the last few years, golf companies have turned to finite element analysis to gain a competitive edge. Adrian Podpirka, a student of Professor Zhigang Suo, recently analyzed the stresses and vibrations produced on a golf club and ball for his solid mechanics class, at Harvard University. Adrian developed an FEA model of a basic golf driver, paying special attention to the geometric and material properties of the shaft and the driver head. Given the scope of the project, he simulated an instantaneous static load instead of a higher-fidelity dynamic load. He first applied a load of 15,000 N to one side of a FEA model of a golf ball with boundary conditions set on the direct opposite side. This allowed him to view the propagation of stress waves through the body of the ball and later examine how the boundaries of materials interacted with each other. It was relatively easy to find the sweet spot, since his analysis accurately measured the instantaneous deformations of both the club and the ball. Adrian then modeled and compared the performance of a hollow body and a solid body driver under the same static load, using a titanium alloy material definition. In this analysis he accurately predicted that the stress exhibited by a hollow driver was much higher than that exhibited by the solid. The solid, therefore, provided better recovery of the lost energy. However, a larger strain was placed on the hollow driver allowing it to transfer more energy back and giving more power to the shot. As can be seen from the results, many golf equipment design challenges can be solved using Abaqus; maximum release velocity, energy transfer parameters, lowest natural frequency, stress wave propagation, and determination of the sweet spot. These capabilities enable golf companies to reduce physical prototyping costs and produce better products more efficiently. Rumor has it that the simulations even helped knock a few points off Adrian s handicap. Comparison between stresses exhibited on solid and hollow drivers. This phenomena is known as the trampoline effect. Download Adrian s full paper at: New Geotechnical Textbook Uses Abaqus FEA Predicting soil behavior by constitutive equations that are based on experimental findings and embodied in numerical methods, such as the finite element method (FEA), is a significant aspect of soil mechanics. Engineers are able to solve a wide range of geotechnical engineering problems, especially inherently complex ones that resist traditional analysis. Applied Soil Mechanics with ABAQUS Applications by Sam Helwany PhD, PE, provides civil engineering students and practitioners with a simple, basic introduction to applying the finite element method to soil mechanics problems. Taking a unique approach, Professor Helwany describes the general soil mechanics for each topic, shows traditional applications of these principles with longhand solutions, and then presents finite element solutions for the same applications, comparing them. The book is prepared with Abaqus software applications enabling readers to experiment with the principles described in the book. This book is an ideal introduction to traditional soil mechanics as well as a guide to emerging methods. Applied Soil Mechanics with ABAQUS Applications Sam Helwany PhD, PE, Associate Professor in the Department of Civil Engineering and Mechanics at the University of Wisconsin- Milwaukee Topics include: Properties of soil Elasticity and plasticity Stresses in soil Consolidation Shear strength of soil Shallow foundations Lateral pressure and retaining walls Piles and pile groups Seepage Bibliographic Information: Hardcover * 400 pages * Wiley: March 16, 2007 ISBN-10: * ISBN-13: INSIGHTS June/July

17 Alliances CT Scans Accelerate Creation of 3D Foot Models for Realistic Simulation The geometrical complexity of the human foot requires an accurate 3D model to precisely simulate its biomechanical behavior. Tools such as MIMICS from Materialise, allow researchers to quickly and easily convert CT Scan data into 3D models for detailed CAD modeling and finite element analysis. In a recent study, researchers used MIMICS, to process CT scan data of the foot region of a 26 year old male. The tool allowed them to separate the bone and soft tissue to create 3D bone structure and soft tissues assembly independent geometry files and 3D models. For the complete definition of the foot structure, 30 different regions were created and reconstructed in 3D. Using *.STL files, the models were exported to CATIA. The foot structure was further defined in CATIA, and volume Boolean operations were performed to achieve an accurate volume of soft tissues. This procedure guaranteed perfect alignment of the cartilages on the bones, an important step in the creation of the finite element model. The assembled model was then imported into Abaqus. Linear and nonlinear elastic constitutive material models were used to characterize the biological materials. Load transmission between ground support and the foot structure was defined by contact pairs at the foot plantar area and the ground. Several results were gathered including pure compression load (weight load) and balanced standing load (weight load + Achilles load). The initial research clearly demonstrates that leveraging CT Scan data to create detailed CAD and FEA models is an extremely efficient approach. The nonlinear FEA model can readily serve as a tool for design optimization of shoe insoles or other foot support devices. Foot model showing peak value stress Download the paper Non-Linear Finite Element Modelling of Anatomically Detailed 3D Foot Model at Non-Linear Finite Element Modelling of Anatomically Detailed 3D Foot Model, by P.J. Antunes and G.R. Dias, Institute for Polymers and Composites, University of Minho, Guimarães, Portugal; A.T. Coelho, Amorim Industrial Solutions, Corroios, Portugal; F. Rebelo, Ergonomics Laboratory, Faculty of Human Kinetics, Technical University of Lisbon, Lisbon, Portugal; and T. Pereira, The Health Sciences School, University of Minho, Braga, Portugal. Fluid Structure Interaction with Abaqus and STAR-CD In partnership with CD-adapco, we have developed a powerful coupled-analysis capability for fluid-structure interaction (FSI) utilizing Abaqus, SIMULIA s technology-leading finite element analysis software suite, and STAR-CD, a marketleading computational fluid dynamics (CFD) software from CD-adapco. Manufacturers and researchers in automotive, aerospace, off-shore, biomedical, consumer, and process industries can leverage this capability to study the influence of fluid flow-induced forces and heat transfer on structural integrity, as well as the impact of nonlinear material response on fluid flow behavior. This allows users to evaluate a wide range of conditions, such as flow-induced vibrations in structures, in-vivo vascular flows, valve dynamics, and fluid-structure applications in consumer goods and packaging. This coupled multiphysics solution also dramatically improves collaboration between fluid dynamics engineers and structural engineers, enabling them to gain a greater understanding of system behavior. This open platform approach ensures that customers may easily integrate this fully supported best-in-class technology. A transient, fluid structure interaction simulation of a flexible baffle in an air stream is enabled by coupling ABAQUS finite element analysis software with computational fluid dynamic (CFD) results from STAR-CD. Use this Powerful FSI Capability to: Leverage industry-standard code coupling based on MpCCI Use proven algorithms for structural analysis and computational fluid dynamics to achieve accurate results Enhance collaboration between diverse disciplines and engineering groups within your supply chain Gain valuable insight into real-world interactions between structures and fluid flow INSIGHTS June/July

18 Events Adieu 2007 AUC 2007 Image Winner This year s best image winner was Arun Sreeranganathan of Georgia Institute of Technology Networking & Annual Banquet The 2007 Users Conference was an exhilarating convergence of customers, partners, and SIMULIA professionals from around the world. With the release of Abaqus Version 6.7, attendees were among the first to view the significant new features and enhancements. They were also able to learn about the SIMULIA strategy, including solutions for multiphysics and Simulation Lifecycle Management. On the first day Airbus publicly announced that it has selected Abaqus as their preferred solution for nonlinear static FEA. This coincided with the keynote address given by Dr. Jean-Francois Imbert, Vice President and Head of Structural Analysis Engineering at Airbus. Dr. Imbert presented an impressive overview of a wide range of simulation applications being deployed at Airbus. Day two was opened by Franz Zieher, Head of CAE Engineering and Technology, Powertrain Systems, for AVL LIST GmbH. He presented details of the CAE-processes and methods being used for powertrain development at AVL. Zieher noted the drive for standardized procedures and outlined how tools for managing simulation data and processes are imperative to track and manage large numbers of simulations. In addition, more than 50 customer presentations and 16 complimentary technology presentations were delivered over the course of the 3-day conference. Special thanks to all of you who contributed papers and presentations. Image and Animation Contest The second annual Image and Animation Contest provided customers with the opportunity to win a new Lenovo laptop computer sponsored by IBM. There were several excellent entries, and the following two were selected as top in their class: His model represents a micromechanical analysis of metallic composites, which is carried out by incorporating digital microstructural images (both 2D & 3D) of the materials in a finite element framework. On the foreground of this image is the principal stress distribution in SiC particles from the 3D simulation of uniaxial loading of a discontinuously reinforced aluminum alloy. The background shows the principal stress distribution in SiC particles from a 2D plane stress simulation of uniaxial loading Animation Winner Sam Lee of Guangzhou Scientific Computing Consultants Co. Ltd won for best animation. This is a simulation of a skyscraper s deformation under earthquake conditions. The 330 m tall building is a well-known landmark in TianJin City, China. All structural members are modeled by beam and shell elements with 600,000 degrees of freedom. The color contour shows the plastic deformation. The simulation utilizes the unique combination of implicit and explicit technologies within the Abaqus Unified FEA product suite to help architects understand how the building will perform during an earthquake. While the conference presentations provided a wealth of information and knowledge, attendees found time to unwind and relax at the welcome and partner receptions. The annual conference banquet was a rare treat as more than 300 delegates took in stunning views of the Eiffel Tower, Notre Dame, and the Grand Palais on a leisurely dinner cruise along La Seine. Prior to boarding, the group gathered in front of the Eiffel Tower for the largest group photo in AUC history. Conference Proceedings SIMULIA customers with an online support account are able to view the Abaqus General Lectures and Tutorials through our support site under Answer 3448 (login required). Copies of the AUC 2007 Proceedings Book and CD are now available online. AUC 2008 The 2008 AUC will return to Newport, Rhode Island. The call for papers is now open! Your contribution of a paper and presentation will ensure the continued growth and success of the AUC. See you in Newport! or 18 INSIGHTS June/July

19 Events 2007 Abaqus Regional Users Meetings and Update Seminars Americas Date September 17 September October 1 2 October 17 Location Cleveland, OH Cincinnati, OH Córdoba, Argentina Houston, TX Europe / South Africa Date Location July Johannesburg, South Africa September Baden-Baden, Germany September Copenhagen, Denmark October 9 Prague, Czech Republic Attend the upcoming Regional User Meeting in your area. Learn about the latest enhancements to Abaqus FEA and the future direction of SIMULIA. Visit our website for more details. October November 5 6 November 7 8 November Las Vegas, NV Toronto, Ontario Plymouth, MI Providence, RI November TBA November 8 9 November November November Turin, Italy Istanbul, Turkey Salzburg, Austria Daventry, United Kingdom Poznan, Poland Asia Pacific Date Location November November November 26 Leuven, Belgium Madrid, Spain Herzelia, Israel June Korea October 24 Bangalore, India October Malaysia October 31 Tokyo, Japan November 2 Osaka, Japan TBA Guilin, China Webinars SIMULIA provides free informational webinars to help you get the most from our products and solutions. Attend upcoming live webinars or request a replay of a recorded webinar and view it at your convenience. Upcoming webinars: July 31 & August 2 Realistic Simulation with SIMULIA Multiphysics Solutions August 28 & 30 Improve Design & Analysis Workflows with Abaqus for CATIA V5 Version 2.5 September 11 & 13 Accelerate Simulation Performance for Industrial Applications in a Compute Cluster Environment October 9 & 11 Realistic Simulation for Offshore Exploration Applications INSIGHTS June/July

20 SIMULIA Helps Keep Me Warm and Dry Simulation for the Real World Developing consumer products for everyday life demands sophisticated engineering practices. From simulating the behavior of advanced materials to understanding the way diapers fit snugly but comfortably, our customers use SIMULIA solutions to understand and improve how consumer products work in the real world. We partner with our customers to deploy realistic simulation methods and technology, which helps them drive innovation and keep consumers smiling. SIMULIA is the Dassault Systèmes Brand for Realistic Simulation. We provide the Abaqus product suite for Unified Finite Element Analysis, multiphysics solutions for insight into challenging engineering problems, and an open PLM platform for managing simulation data, processes, and intellectual property. Learn more at: