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MODELING AND FATIGUE ANALYSIS OF AUTOMOTIVE WHEEL RIM WITH DIFFERENT MATERIALS

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MODELING AND FATIGUE ANALYSIS

OF AUTOMOTIVE WHEEL RIM WITH

DIFFERENT MATERIALS

MERIGE PHANI SRUJAN*

Department of Mechanical Engineering, Chaitanya Bharathi Institute of Technology Gandipet-500075, Hyderabad, INDIA

MAHANKALI YASHWANTH

Department of Mechanical Engineering, Chaitanya Bharathi Institute of Technology Gandipet-500075, Hyderabad, INDIA

P ANJANI DEVI

Assistant Professor, Department of Mechanical Engineering,

Chaitanya Bharathi Institute of Technology, Gandipet-500075, Hyderabad, INDIA *corresponding author: phani.srujan@gmail.com

Abstract: In the design of automobile, the industry is exploringpolymericmaterial in order to obtain reduction of weight withoutsignificantdecrease in vehicle quality and reliability. Fuel consumption of the vehicle is directly proportional to the weight of the wheel rim. Thusin this project a standard wheel of four wheeler ischosenand analyzed by applying loads and using different materials .AluminumAlloy,Magnesium Alloy, PEEK,PEEK with 20% Glassfiber, PEEK with 30% GlassFiber are the materials chosen.The whole design is made by using SOLIDWORKS as per original equipment manufacturer(OEM’S)requirement. Analysis has been carried out using ANSYS todetermine deformation and fatigue life of the wheel. The whole analysisisdonebymeansofsoftwarethereforeresultandobservationsaretrustworthy and met ourexpectation.

Keywords: SOLIDWORKS, ANSYS, PEEK(Polyether Ether Ketone) 1. Introduction

Car wheels need to be durable and able to carry around weight. You won't find many spoke designs with these rims. They're usually as solid as possible. But that doesn't mean your options aren't varied when looking for replacements. The most important thing to remember is to purchase the same size rims while replacing unless plane contains vehicle modification.Reducing unsprung mass makes wheels lighterthus handling can be improved. Fuel consumption is reduced by decreasing the overall vehicle weight. Heat conduction must be taken care for better working of brakes and overheating.

The part of the automobile which undergoes both static and fatigue loads in parallel is a wheel. The circular metal frame on which the rubber tyres are mounted is wheel rim. These are manufactured from sheet metal which are bent to produce circular profile. Calibration is mandatory to avoid manufacturing defects. Then both the ends are welded to produce a perfect circle with constant radius. Holes are provided at required places for nuts and to reduce the overall weight of the rim. Keeping an eye on reducing the weight of the wheel helps in better fuel consumption rate of the vehicle.

The wheel might seem to oscillate laterally (side to side) or appear to move up and down (out of round). Motorcycle rims can be casually inspected by supporting the bike on the centre stand or other stand and spinning them while viewing side on or edgewise. A sharp pencil to the fork or swing arm is used to help measure smaller variations. If the wheel is badly out of true, especially if the cause is from an accident repair should be done. Sometimes the cause is just from lazy spoke maintenance. The wheel can slowly drift out of true over time.

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2. Modeling of wheel rim

All the design parameters of the designed wheel rim mentioned in the Table: 2.1. Wireframe and solid models are shown in the Fig: 2.1.

Table 2.1 Dimensions Wheel rim model

Fig: 2.1. Wire frame and solid model of designed wheel rim.

The wheel rim solid model (para solid file format) is imported to ANSYS and the model is free meshed and thus finite element model is created. The 1/5th part of meshed wheel rim is shown in the fig 2.2.

Fig: 2.2. Meshed model of rim

3. Finite Element Analysis

Finite element analysis is a powerful tool for solve many numerical problems encountered in analysis. In this method, a complex region known as continuum is divided into simple shapes of geometry known as finite elements for which the analysis is carried out. The material properties and governing relations are specified and expressed in terms of unknown values at the element corner. Considering the loading and constraints in an assembly process results in set of equations, which gives the approximate behaviour of the continuum.

3.1.Fatigue mechanism:

The existence of repeated or cyclic stresses at some point of the component is the basic feature that underlies all specific fatigue mechanisms. The origin of damage is caused by the cyclic stresses which develops into a crack and finally leads to fracture. The way those cyclic stresses arise in a specific point of the component results in

Outer diameter 558.8 mm

Hub hole diameter 78 mm

Bolt hole diameter 20 mm

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different fatigue failure mechanisms. Sometimes the existence of other concurrent or synergistic damaging mechanisms such as wear or corrosionare also related to them.

3.2.Material properties:

Table: 3.1 Material Properties

Property Al Alloy PEEK PEEK 20%

GF

PEEK 40%GF

Units

Density 2770 1320 1370 1450 Kg/m^3

Coefficient of Thermal Expansion

0.000023 0.0000468 0.000045 0.0000423 C^-1

Specific Heat 875 1470 1390 1270 j/Kg C

Compressive Yield Strength

2800x10^5 118x10^6 2.7X10^8 3.1X10^8 Pa

Tensile Ultimate Strength

3100 100x10^6 1X10^8 1X10^8 Pa

Reference Temperature

22 22 22 22 C

Young’s Modulus 7.1x10^10 3.6x10^9 2.2X10^10 4.5X10^9 Pa

Poisson’s Ratio 0.33 0.39 0.4556 0.48

Bulk Modulus 6.9608x10^10 6.9608*10^10 8.25X10^10 3.75X10^10 Pa

Shear Modulus 2.6692x10^10 1.4x10^9 7.5X10^9 1.52X10^9 Pa

3.3. Boundary conditions and Loading

 A pressure of 35-40 psi is applied on the outer surface of the rim.  Bolt holes are constrained in all directions.

 A constant load of 2500N is applied throughout the inner surface of hub diameter

3.4. Steps in doing a Fatigue Evaluation:

 Enter POST1 and Resume Your Database

 Establish the Size, Fatigue Material Properties, and Locations  Define material fatigue properties.

 Store Stresses and Assign Event Repetitions and Scale Factors  Activate the Fatigue Calculations

4. Results and Discussions

Static analysis has been done using 5 different materials namely Aluminium alloy, Magnesium alloy, PEEK, PEEK 20%GF, PEEK 30%GF. Analysing the results and graphs of static analysis, only 3 materials were selected and Fatigue analysis has been done. All material properties, result tables, graphs are discussed below.

4.1 Results obtained from software:

Table 4.1 Displacement, Von misses stress and Fatigue strength of selected materials

Material Displacement(mm) Von misses stress(Mpa) Fatigue strength(cycles)

Aluminium alloy 0.186021 48.326 1.32*105

Magnesium alloy 0.247555 32.29 1.2*105

PEEK 0.123927 124.34 -

PEEK 20%GF 0.114394 132.087 -

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4.2 Deformation plots:

Fig 4.1 Deformation of Al alloy (left) and Mg alloy (right) 

The maximum deformation produced in Aluminium alloy is 0.186021 mm and Magnesium alloy is 0.247555 mm is shown in the fig 4.1. It is observed that the deformation is maximum at node no 96202 and minimum at node no 2197 for Aluminium alloy and maximum at node no 39816 and minimum at node no 38816 for Mg alloy.

Fig 4.2 Deformation of PEEK (left) and PEEK20%GF (right)

The maximum deformation produced in PEEK is 0.123927 mm and PEEK 20%GF is 0.114394 mm is shown in the fig 4.2. It is observed that the deformation is maximum at node no 24793 and minimum at node no 986 for PEEK and maximum at node no 2524 and minimum at node no 984 for PEEK 20%GF.

Fig 4.3 Deformation of PEEK 30%GF (left) and Plot of Deformation vs Material (right)

The maximum deformation produced in PEEK 30%GF is 0.186021 mm anddeformations produced by all the 5 materials are plotted on a graph is shown in the fig 4.3.It is observed that the deformation is maximum at node no 2448 and minimum at node no 58 for PEEK 30%GF.

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4.4 S-N curves:

 

Fig 4.4 S-N curve of Aluminium alloy (left) and Mg alloy (right)

The fatigue strength of Aluminium alloy is 1.32*105 cycles and Magnesium alloy is 1.2*105 cycles. The S-N curve for the same is shown in the fig 4.4. Stress range in Mpa is showed on Y-axis and Life (no. of cycles) is specified on X-axis.

 

Fig 4.5 S-N curve of PEEK 30%GF (left) and Plot of Fatigue life vs Material (right)

The fatigue strength of PEEK 30%GF is 2.17*105 cycles and plot of Fatigue life vs Materials is shown in the fig 4.5. Stress range in Mpa is showed on Y-axis and Life (no. of cycles) is specified on X-axis.

Fatigue Life of the 3 selected materials are plotted on a graph and shown in the fig 7.10. No of cycles (x105) is shown on the Y-axis and Material is specified on the X-axis. It is evident from the graph that the Fatigue life of PEEK 30%GF is higher than other materials.

5. Conclusions

a. The von misses stresses developed in PEEK 30%GF during static analysis is 140.056N/mm2 at load 21.3kN the stress is below yield stress of material. For these stress ranges we have to find at what number of cycles the component is yielding or crack is going to initiate.

b. PEEK 30%GF material rim starts to fail at Nf =2.17*105Cycles.The von misses stresses developed in

Aluminium alloy during static analysis is 48.326N/mm2 at load 21.3KN the stress is below yield stress of material for these stress range we have to find at what number of cycles the component is yielding or crack is going to initiate.

c. The von mises stresses developed in Magnesium alloy during static analysis is 32.294N/mm2 at load 21.3KN the stress is below yield stress of material for these stress range we have to find at what number of cycles the component is yielding or crack is going to initiate.

d. During fatigue analysis of Magnesium alloy starts to fail at Nf =1.2*105Cycles.

e. From results we can make out, in rim of PEEK 30%GF material the Number of cycles to failure (Nf) =

2.17*105Cycles is greater than Aluminium and Magnesium. Hence PEEK 30%GF is more feasible to use than Aluminium.Hence PEEK 30%GF has more life and durability compared to Aluminium.

6. References

[1] K. Mahadevan and Balaveera Reddy, “Design Data Hand Book”. [2] “Finite Element Analysis”, Chandra Pautla.

[3] “Ansys User Manual”

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[5] “Metal Fatigue”, Ralfh Stefunson, Ali Fatemi & A.O. Cuph. [6] “MSC Fatigue User Manual”

[7] Metal_fatigue_in_engineering by Stefan.

[8] Fatigue Life Analysis of Aluminium Wheels by Simulationof Rotary Fatigue TestLiangmo Wang* - Yufa Chen - Chenzhi Wang - Qingzheng WangSchool of Mechanical Engineering, Nanjing University of Science & Technology, China

[9] Fatigue properties of a cast Aluminium alloy for rims of car wheels.

[10] J.Stearns, P.C.Lam, and T.S.Srivastsans “An analysis of Stress and Displacement in a Rotating Rim subjected to Pressure and Radial Loads.” Division of Advanced Product and Process Technology. The Goodyear Tyre and Rubber Company, Akron, Ohio, U S A. April 14,2000.

[11] Smithers Scientific Services, Inc.”Wheel Test Center”Smithers Scientific Services, Inc. 425 West Market Street, Akron, OH 44303-2099 U.S.A. 1997

[12] Pottinger, M.G., Arnold, G.A., Marhall, K.D., [1976] “The effect of test speed and surface curvature on cornering properties of wheel”.

[13] Ering Tonuk, Y.samin Unlusoy [2001], “Prediction of Automobile tyre cornering force characteristics by finite element modeling and analysis”.

[14] Wright,D.H., [1983] “Test Method for Automotive Wheels, Institute of Mechanical Engineering” Paper No.c278/83,in Automobile Wheels and Tyres.

[15] Cameron. Lonsdale and Francois. Demility. [1999] “Wheel Rim Residual Stress Measurement”.

[16] Konishi,H.,Fujiware,A.,Katsura,T., Takeuchi,K.,and Nakata,M., 1996,”Impact Strength of Aluminium alloy Wheel (Influence of Disk and Rim Rigidity on the JWL Impact Strength of Aluminium alloy Wheel)”Nippon Kikai Gakkai Ronbunshu,C.Hen,Vol.62,n 599,pg. 2884-2890.

[17] Mizoguchi, T., Nishimura, H., Nakata, K., and Kawakami, J., 1982, “Stress Analysis and Fatigue Strength Evalution of Sheet Fabricated 2-Piece Aluminium alloy Wheels for Passenger Cars.”R&D,Reserch & Development (Kobe Steel, Ltd),Vol.32,n 2,pg.25-28. Konishi,H.,Fujiwara,A.,Katsura, T., Takeuchi,K.,and Nakata,M.,[1997],”Impact Strength of Aluminium alloy Disk Wheel” Nippon Kikai Gakkai Ronbunshu,R&D,Reserch & Development (Kobe Steel, Ltd), Vol 47, n 2,pp.25-28.

[18] Fischer, G.; Grubisic, V.: Biaxial Wheel / Hub Test Facility, Proceedings of the 4th International User Meeting,September 21 st,1999 in Darmstadt LBF-Report No.TB-219[2000].

[19] Rupp, A., Grubisic, V.: Reliable and Efficient Measurement of Suspension Loads on Passenger-cars and Commercial Vehicles International Conference and Exibition, Ancona, 29.-30.6.1995.ATA Orbassano[1995], s. 263-273.

Figure

Table 2.1 Dimensions Wheel rim model
Table 4.1 Displacement, Von misses stress and Fatigue strength of selected materials
Fig 4.1 Deformation of Al alloy (left) and Mg alloy (right)  
Fig 4.4 S-N curve of Aluminium alloy (left) and Mg alloy (right)

References

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