DESIGN AND ANALYSIS OF COMPOSITE DRIVE SHAFT

Transcription

1 DESIGN AND ANALYSIS OF COMPOSITE DRIVE SHAFT KETHAVATH RAJESH Mr.A.RAMESH(M.Tech) Asst.Professor SDEPARTMENT OF MECHANICAL ENGINEERING MALLA REDDY ENGINEERING COLLEGE (AUTONOMOUS) (An Autonomous Institution approved by UGC and affiliated to JNTUH, Approved by AICTE, Accredited by NAAC with A Grade and NBA & Recipient of World Bank Assistance under TEQIP Phase- II S.C.1.1) Maisammaguda, Dhulapally (Post. Via.Kompally), Secunderabad Abstract Drive shaft is the most important component to any power transmission application; automotive drive Shaft is one of this. A drive shaft, also known as a propeller shaft or Cardan shaft, it is a mechanical part that transmits the torque generated by a vehicle's engine into usable motive force to propel the vehicle. Substituting composite structures for conventional metallic structures has many advantages because of higher specific stiffness and strength of composite materials. This work deals with the replacement of conventional two-piece steel drive shafts with a single-piece aluminum silicon carbide composite drive shaft for an automotive application. The design parameters were optimized with the objective of minimizing the weight of composite drive shaft. The CAD model is designed in SOLID WORKS PREMIUM 2014 SOFTWARE. To obtain the stress and deformation values solid works simulation software was used. By comparing the results proper material for drive shaft can be selected. Introduction to drive shaft: A drive shaft, driveshaft, driving shaft, propeller shaft (prop shaft), or Cardan shaft is a mechanical component for transmitting torque and rotation, usually used to connect other components of a drive train that cannot be connected directly because of distance or the need to allow for relative movement between them.

2 As torque carriers, drive shafts are subject to torsion and shear stress, equivalent to the difference between the input torque and the load. They must therefore be strong enough to bear the stress, whilst avoiding too much additional weight as that would in turn increase their inertia. To allow for variations in the alignment and distance between the driving and driven components, drive shafts frequently incorporate one or more universal joints, jaw couplings, or rag joints, and sometimes a splined joint or prismatic. Drive Shaft description: As mentioned above, recent developments in the applications of composite materials have shown that a composite material structural member used in power transmission can be of a great assistance in overcoming a few of the problems faced with conventional drive shafts. The assessment of the extent of this fact is the essence of this work. Therefore a good understanding of the drive shaft would be a prerequisite and is discussed in the following section. A drive shaft, propeller shaft (prop shaft), or Cardan shaft is a mechanical component for transmitting torque and rotation, usually used to connect other components of a drive train that cannot be connected directly because of distance or the need to allow for relative movement between them. Drive shafts are carriers of torque. They are subject to torsion and shear stress, equivalent to the difference between the input torque and the load. They must therefore be strong enough to bear the stress, whilst avoiding too much additional weight as that would in turn increase their inertia. Therefore a drive shaft is expected to function, as follows. It must transmit torque from the transmission to the differential gear box. The drive shaft must also be capable of rotating at very high speeds as required by the vehicle. The drive shaft must also operate through constantly changing angles between the transmission, the differential and the axels. The length of the drive shaft must also be capable of changing while transmitting torque. o Thus the design of a drive shaft presents itself as a case of torsion problem. Further, with regard to the conventional drive shafts

3 following shortcomings were observed some of which could be addressed better with a composite shaft. o They have less specific modulus and strength o Increased weight o Conventional steel drive shafts are usually manufactured in two pieces to increase the fundamental bending natural frequency because the bending natural frequency of a shaft is inversely proportional to the square of beam length and proportional to the square root of specific modulus. Therefore the steel drive shaft is made in two sections connected by a support structure, bearings and U- joints and hence overall weight of assembly will be more. o Its corrosion resistance is less as compared with composite materials. o Steel drive shafts have less damping capacity. Since a drive shaft is a case of torsion problem an understanding of the methodology of solving such a problem in structural mechanics is necessary. Drive Shaft The drive shaft, or cardan shaft as it is sometimes called, is a cylindrical piece of metal, which plays a crucial role in the operation of a motor vehicle. Main drive shafts are tubular and are usually constructed from steel. They will generally be of a large diameter and hollow because weight plays a large part in the efficiency of their performance. It is for this very reason that some have aluminum incorporated in their makeup. There are also short drive shafts, which are used to connect the main drive shaft to the wheels themselves. In these cases, and in front-wheel drive vehicles where the engine and wheels are in close proximity, these short drive shafts are not hollow but solid pieces of metal. Drive shaft working While the importance of an engine to the running of an automobile is well known, it can be argued that the drive shaft plays an equally vital role. The drive shaft acts as a medium for transferring the power generated by the engine to the wheels, enabling them to turn. This in turn puts the vehicle in motion.

4 The force that is transmitted by the drive shaft is referred to as torque. Torque is basically the technical term to describe the force associated with a twisting or spinning motion. Because drive shafts have to endure conditions that could cause them to bend or break they are made to be flexible. Flexible in this sense does not mean the ability to bend. What it speaks to is an allowance for some small degree of movement at the points where the drive shafts are connected. This is accomplished via what are known as universal joints, or u-joints. It is necessary for drive shafts to be straight and balanced. If this is not so vibrating will result. This can lead to damage to the components that are connected to the drive shaft. One example is the engine, which is turning at high speed. The importance of the drive shaft is best appreciated in circumstances where it bridges the gap between inconveniently located components. This inconvenience can arise because of the component s long distance apart, or their awkward positioning/alignment. Fig: drive shaft Purpose of the Drive Shaft (or Propeller Shaft): The torque that is produced from the engine and transmission must be transferred to the rear wheels to push the vehicle forward and reverse. The drive shaft must provide a smooth, uninterrupted flow of power to the axles. The drive shaft and differential are used to transfer this torque. Functions of the Drive Shaft: First, it must transmit torque from the transmission to the differential gear box. During the operation, it is necessary to transmit maximum low-gear torque developed by the engine.

5 The drive shafts must also be capable of rotating at the very fast speeds required by the vehicle. The drive shaft must also operate through constantly changing angles between the transmission, the differential and the axles. As the rear wheels roll over bumps in the road, the differential and axles move up and down. This movement changes the angle between the transmission and the differential. The length of the drive shaft must also be capable of changing while transmitting torque. Length changes are caused by axle movement due to torque reaction, road deflections, braking loads and so on. A slip joint is used to compensate for this motion. The slip joint is usually made of an internal and external spline. It is located on the front end of the drive shaft and is connected to the transmission. Literature Survey: Composites have high specific modulus, strength and less weight. The fundamental natural frequency of carbon fiber drive shaft can be twice as that of the steel or aluminum, because the carbon fiber composite material has more than 4 times the specific stiffness, which makes it possible to manufacture the drive shaft of passenger cars in one piece. A one piece composite shaft can be manufactured so as to satisfy the vibration requirements. This eliminates all the assembly, connecting the two piece steel shaft and thus minimizes the overall weight, vibrations and cost. Due to weight reduction fuel consumption will be reduced. They have high damping capacity and hence they produce less vibrations and noise. They have good corrosion resistance, greater torque capacity, longer fatigue life than steel and aluminum. Mechanical characterization of Al- SiC composite done in previous work by Behera et al. [2013], Wang et al [2008], Pathak et al. [2006] The hardness, impact strength, and material toughness were evaluated. The improved value of coefficient of thermal expansion for Aluminum composites is one of the reasons they are widely used in electronics industry as studied by Martin et al. [2011], Dunia Abdul Saheb[2011], Occhionero et al.[2010], Wang et al.[2006]. Composite drive shafts Introduction:

6 Composite materials have been widely used to improve the performance of various types of structures. Compared to conventional materials, the main advantages of composites are their superior stiffness to mass ratio as well as high strength to weight ratio. Because of these advantages, composites have been increasingly incorporated in structural components in various industrial fields. Some examples are helicopter rotor blades, aircraft wings in aerospace engineering, and bridge structures in civil engineering applications. Some of the basic concepts of composite materials are discussed in the following section to better acquaint ourselves with the behaviour of composites. Basic Concepts of Composite Materials: Composite materials are basically hybrid materials formed of multiple materials in order to utilize their individual structural advantages in a single structural material. The constituents are combined at a macroscopic level and are not soluble in each other. The key is the macroscopic examination of a material where in the components can be identified by the naked eye. Different materials can be combined on a microscopic scale, such as in alloying of metals, but the resulting material is, for all practical purposes, macroscopically homogeneous, i.e. the components cannot be distinguished by the naked eye and essentially acts together. The advantage of composite materials is that, if well designed, they usually exhibit the best qualities of their components or constituents and often some qualities that neither constituent possesses. Some of the properties that can be improved by forming a composite material are strength, fatigue life, stiffness, temperature-dependent behaviour, corrosion resistance, thermal insulation, wear resistance, thermal conductivity, attractiveness, acoustical insulation and weight. Naturally, not all of these properties are improved at the same time nor is there usually any requirement to do so. In fact, some of the properties are in conflict with one another, e.g., thermal insulation versus thermal conductivity. The objective is merely to create a material that has only the characteristics needed to perform the designed task. There are two building blocks that constitute the structure of composite materials. One constituent is called the reinforcing phase and the one in which it is embedded is called the matrix. The reinforcing phase material may be in the form of fibers, particulates, flakes. The matrix phase materials are generally

7 continuous. Examples of composite systems include concrete reinforced with steel, epoxy reinforced with graphite fibers, etc. Classification of Composites: Composite Material: A material composed of 2 or more constituents is called composite material. Composites consist of two or more materials or material phases that are combined to produce a material that has superior properties to those of its individual constituents. The constituents are combined at a macroscopic level and or not soluble in each other. The main difference between composite and an alloy are constituent materials which are insoluble in each other and the individual constituents retain those properties in the case of composites, whereas in alloys, constituent materials are soluble in each other and forms a new material which has different properties from their constituents. Material properties of aluminum silicon carbide: Baseline 3.0µm SiC- 0.7µm SiC- 3.0µm SiC- 0.7µm SiC- Alloy 18% vol % 18% vol % 25% vol % 25% vol % Property 2124 (T4) 2124/SiC/18p 2124/SiC/18p 2124/SiC/25p 2124/SiC/25p comparison as-compacted as-compacted as-compacted as-compacted billet (T4) billet (T4) billet (T4) billet (T4) Density (g/cc) Tensile modulus (Gpa) Strain to Failure (%) % Yield stress (Mpa) Ultimate Tensile strength (Mpa) Introductions to Solid Works: Solid works mechanical design automation software is a featurebased, parametric solid modeling design tool which advantage of the easy to learn windows TM graphical user interface. We can create fully associate 3-D solid models with or without while utilizing automatic or user defined relations to capture design intent. Parameters refer to constraints whose values determine the shape or geometry of the model or assembly. Parameters can be either numeric parameters, such as line lengths or circle diameters, or geometric parameters, such as tangent, parallel, concentric, horizontal or vertical, etc. Numeric parameters can be associated with each other through the use of relations, which allow them to capture design intent. Basic Concepts of Analysis: The software uses the Finite Element Method (FEM). FEM is a numerical technique for analyzing engineering designs. FEM is accepted as the standard analysis method due to its generality and suitability for computer implementation. FEM divides the model into many small pieces of simple shapes called elements effectively replacing

8 a complex problem by many simple problems that need to be solved simultaneously. Elements share common points called nodes. The process of dividing the model into small pieces is called meshing. Von misses failure criteria The von Mises yield criterion suggests that the yielding of materials begins when the second deviatoric stress Invariant reaches a critical value. It is part of a plasticity theory that applies best to ductile materials, such as metals. Prior to yield, material response is assumed to be elastic. In materials science and engineering the von Mises yield criterion can be also formulated in terms of the von Mises stress or equivalent tensile stress, a scalar stress value that can be computed from the Cauchy stress tensor. In this case, a material is said to start yielding when its von Mises stress reaches a critical value known as the yield strength, The von Mises stress is used to predict yielding of materials under any loading condition from results of simple uniaxial tensile tests. The von Mises stress satisfies the property that two stress states with equal distortion energy have equal von Mises stress. von misses Fig: von missses S F. S = σ + σ + σ (σ σ + σ σ + σ σ ) Modeling of Drive Shaft: Drive shaft is modeled with proper dimensions in solid works. The design of composite drive shaft is as follows Draw the sketch with dimensions as shown below Revolve the sketch with base axix:

9 By using the extrude cut and mirror features we finally get the drive shaft model Finite Element Analysis Introduction calculating the strength and behaviour of engineering structures. It can be used to calculate deflection, stress, vibration, buckling behaviour and many other phenomena. It also can be used to analyze either small or large scale deflection under loading or applied displacement. It uses a numerical technique called the finite element method (FEM). In finite element method, the actual continuum is represented by the finite elements. These elements are considered to be joined at specified joints called nodes or nodal points. As the actual variation of the field variable (like displacement, temperature and pressure or velocity) inside the continuum is not known, the variation of the field variable inside a finite element is approximated by a simple function. The approximating functions are also called as interpolation models and are defined in terms of field variable at the nodes. When the equilibrium equations for the whole continuum are known, the unknowns will be the nodal values of the field variable. Simulation on Composite Drive Shaft: Meshing: Finite Element Analysis (FEA) is a computer-based numerical technique for

10 Maximum von-misses stress Analysis results Material: aluminum silicon carbide. Total deformation Maximum von misses stress Maximum strain Maximum strain Total Deformation Buckling analysis Material: steel Buckling analysis results at different modes Material: steel

11 Material: composite aluminum silicon carbide

12 Aluminum silicon carbide has shown less weight when compared with steel shaft References Conclusion: Composite drive shaft is modeled and analyzed by using solid works 2014 Material properties and uses of composite materials are studied Composite drive shaft is modeled in solid works by using required commands Then analysis is done on drive shaft by using different materials such as steel and aluminum silicon carbide Stress, strain and deformations are found out for two materials (i.e; steel and aluminum silicon carbide) Results of stress, strain and deformations are tabulated 1. Jones,R.M., 1990, Mechanics of Composite Materials, 2e, McGrawHill Book Company, New York. 2. AurtarK.Kaw, 1997, Mechanics of Composite Materials, CRC Press, New York..Belingardi.G, Calderale.P.M. and Rosetto.M.,1990, Design Of Composite Material Drive Shafts For Vehicular Applications, Int.J.ofVehicle Design, Vol.11,No.6,pp Jin Kook Kim.DaiGilLee, and Durk Hyun Cho, 2001, Investigation of Adhesively Bonded Joints for Composite Propeller shafts, Journalof CompositeMaterials, Vol.35, No.11, pp Dai Gil Lee, et.al, 2004, Design and Manufacture of an Automotive Hybrid Aluminum/Composite Drive Shaft, Journal of CompositeStructures, Vol.63, pp Agarwal B. D. and Broutman L. J., 1990, "Analysis and performanceof

13 KETHAVATH RAJESH A.RAMESH M.Tech, Machine Design,Dept. of Mechanical Engineering,MallaReddy Engineering College. id: Assistant professor, Dept. of Mechanical Engineering, Malla Reddy Engineering College. id: