Advanced Vehicle Performance by Replacing Conventional Vehicle Wheel with a Carbon Fiber Reinforcement Composite Wheel

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1 Advanced Vehicle Performance by Replacing Conventional Vehicle Wheel with a Carbon Fiber Reinforcement Composite Wheel Jyothi Prasad Gooda Technical Manager Spectrus Informatics Pvt..Ltd. No. 646, Ideal Homes, 3 rd Floor Sai Plaza BMA Layout, Rajarajeshwarinagar Bangalore jyothiprasad@spectrus-group.com ABSTRACT Automotive industry is going through a transformational phase with increased pressure to reduce weight, increase volume and remain sustainable. Composites have traditionally played a key role in achieving these objectives, although at a high cost and low volume requirements. With the advancement in the composites technologies, resulting in availability of low cost raw materials, support for high volume production composites usage and adoption in automotive industry is going a key turning point. Several systems and sub-systems of the automobile can be replaced with components made up of composites materials. In our project, we have carried out an exercise to understand the benefits of replacing conventional wheel material with carbon fiber reinforcement composite for the vehicle wheel. Here, we could reduce wheel weight, unsprung mass of the vehicle, and improved rotation inertia. We considered carbon fiber reinforcement and epoxy resin system. Several boundary and loading conditions were considered, such as tire inflation pressure, cornering, accelerating or breaking and vehicle weight. A linear static analysis of the wheel was carried out in Optistruct and the results calculated empirically. The wheel weight was reduced by 40-50% when compared to conventional materials. Keywords: CFRP, unsprung mass, FEM, wheel weight, linear static analysis, Optistruct Introduction: - The ratio between a vehicles sprung and unsprung mass significantly affects the control characteristics and handling of the vehicle. The lighter the unsprung mass, the faster the response time will be, allowing a more consistent vertical load through the tyres and consequently a more consistent level of friction between the car and the road. This allows for better acceleration, braking and cornering performance for the vehicle, as well as increased driver confidence, providing an advantage on the track. This paper will investigate the reduction of unsprung mass through the development of a composite wheel. According to previous studies automakers strives to develop composite wheel rim to use with lightweight aluminium centre. Now due to availability of advanced material and their remarkable mechanical properties automakers are able to develop one piece carbon fibre wheel. In this paper an attempt has been made to replace conventional passenger carrying vehicle wheel with a carbon fibre reinforced composite laminate material. The process is carried out by modelling a composite wheel followed by structural analysis using hyper works pre-processor Optistruct. The strength of the wheel is determined by considering extreme boundary conditions it will bear while operational use. Assuming a vehicle that is symmetric in the front view, such that the vehicle has the same left and right side weights in a static equilibrium position. This paper consists of various sections including the introduction and conclusions. Sections explaining about modelling of a wheel carried out with strength analysis using hyperworks preprocessor Optistruct. Results and wheel behaviour is discussed in areas showing stresses and deflections, followed by benefits, challenges and future plans. 1

2 PROCESS METHODOLOGY: Fig-1-CAD MODEL Fig-2-MID SURFACE Fig-3-FE MODEL Wheel component is processed for FE modelling starting from mid surface extracting to discretising using fine QUAD-4 and TRIA-3 elements. Material information:- Composite materials are light weight with high specific stiffness and strength compared to traditional isotropic materials. We have considered orthotropic laminate properties with available material card MAT 8 in hyperworks material library. This defines the material properties for linear temperature independent orthotropic material for two-dimensional elements. PLY property assignment:- 2

3 Fig:-4-ply layup of spokes (12 plies=3.030mm thick) Fig:-5-ply layup of Rim (8 plies=2.424mm thick) In order to keep associativity between plies positioned in different locations and to provide required continuous flow of plies a composite property card available in Hyperworks is used. PCOMPP Composite laminate property for Ply-Based modelling, which defines the properties of a composite laminate material is used in plybased composite definition. Fig:-6-ply layup of Hub (10 plies=4.848mm thick) Load cases:- In order to ensure that the wheel would not fail, four critical load cases where developed to represent the most extreme conditions the wheel rim would experience during operational use. A detailed description for each load cases used in the analysis is as follows. 1) Cornering Load This is the most performance critical and extensively examined parameter of the loading cases. Cornering load is specifically applied at the rim beat location while taking of sharp corners. 3

4 force acting on the wheel. Equation describes the lateral Fig:-7-cornering or lateral force acting on to the wheel 2) The second Load case is acceleration and breaking; the loading of which is the same between the two. The design goal in this case is to minimize the fore and aft rotation of the wheel under acceleration and breaking loads, or what is known as toe change Equation describes the lateral force acting on the wheel Fig:-8-Acceleration or Braking force acting on to the wheel 3) The third load case is the pressurization of the wheel. This case is intended to simulate the tire being over inflated in order to seat the tire bead of the rim. Since the wheel is deflated prior to use, there is no performance concerns during this load case. The only requirement of this case is to ensure that the wheel rim does not fail during this process. Pressure has been applied to total circumference of the rim. Fig:-9- figure indicates the pressure acting on to the wheel 4) Loading the static force Vertical F=6450N (total bearing force from the vehicle weight). Assuming vehicle to be symmetric equilibrium longitudinally. Vehicle weight has been applied on wheel and axle fixing locations Vehicle load distributed to four bolting location 4

5 Fig:-10- figure indicates the vehicle weight applied. 5) Fifth load case applied on the combination of loading cases (cornering+ Braking or acceleration+ Inflation pressure+ vehicle weight) Results & Discussions:- 1) Cornering subcase results Fig:-11- Laminate Displacement plot Fig:-12- Laminate stress plot 2) Acceleration and breaking subcase results Fig:-13- Laminate Displacement plot Fig:-14- Laminate stress plot 3) Tyre inflation pressure subcase results 5

6 Fig:-15- Laminate Displacement plot Fig:-16- Laminate stress plot 4) Vehicle weight subcase results Fig:-17- Laminate Displacement plot Fig:-18- Laminate stress plot 5) Load=Combined ( pressure+ cornering+ Acceleration/braking+ vehicle weight) Fig:-19- Laminate Displacement plot Fig:-20- Laminate stress plot Results been simulated using Hyperview post processor tool allowing to examined ply wise and whole wheel laminate deformed shape and stresses. 6

7 Benefits Summary:- HyperWorks benefits realized are o Very detailed and advanced composite modeling options in HyperWorks helps users to perform complete composite pre and post processing o Resourceful composite material options are available in HyperWorks to consider all possible mechanical properties data input cards o User friendly graphical user interface Benefits of light weight composite wheel o Increased acceleration o Reduced stopping distance o Improved steering, handling and response o Improved mechanical grip o Reduced road noise o Reduced fuel consumption Challenges:- Fiber orientation in the part determines the strength of the part. As the HyperMesh can simulate only unidirectional plies, it made our task very challenging to meet the required strength and stiffness of the composite wheel, which was bi-directional. Future Plans:- We plan to do internal benchmarking exercise for additional carbon wheel designs without needing to have multiple iterations for achieving target stiffness and strength. We plan to explore additional options to provide bidirectional and multi directional fiber orientation methods to reduce the complexity of the tasks and minimize the efforts Conduct detailed study of suitability of carbon wheels for different sectors of automotive and transport industry. Explore opportunities with the OEMs and Tier 1 suppliers to demonstrate the benefits of carbon wheel. Design and develop components using eco friendly composites materials in the automotive industry. Conclusions:- The use of a CFRP wheel has the potential to improve the performance of the vehicle by lowering the unsprung mass and the rotational inertia of the wheel assembly. CFRP Wheel has been verified by using linear static analysis with various loading conditions Displacement of the wheel is safe due to all applied loadings Overall weight of the wheel was reduced by 40-50%. Stresses of the all plies are below the ultimate values of the in-plane and inter laminar values 7

8 ACKNOWLEDGEMENT Thanks to the Spectrus management team for giving us the opportunity to work on the advanced composites engineering projects. Thanks to the composites engineering team of Spectrus for constant guidance, support and for sharing experience to complete the project timely. Thanks for the Altair technical support team and Composites technologies customer support team for their extended support and coaching during the project. REFERENCES ACME RACING. (2010). ACME RACING DESIGN LOADS. CANBERRA. DORWORTH, L., GARDINER, G., & MELLEMA, G. (2009). ESSENTIALS OF ADVANCED COMPOSITE FABRICATION AND REPAIR. Aaron Ressa, Ohio State University 2013, O B Reeksting, 1 June 2005, FAILURE ANALYSIS ON CARBON FIBRE WHEEL. ` 8