Yi Zhou, Dong Ma BEIQI FOTON MOTOR CO. The Integrated Application of MSC Software in Lower Control Arm Development

Transcription

1 Yi Zhou, Dong Ma BEIQI FOTON MOTOR CO. The Integrated Application of MSC Software in Lower Control Arm Development

2 ABSTRACT 1. Introduction 2. Model Building and Materials 3. Loads and Boundary Conditions 4. Strength Calculating Results 5. Fatigue Analysis of the Arms 6. Conclusion

3 Introduction Based on the development of the lower control arm, the paper does several simulations to the different arm designs with the application of multi-body dynamics, finite-element calculation and fatigue analysis, targeting the problems found in real proving ground tests.

4 Introduction fig 1-1 crack location fig 1-2 crack location (detail)

5 Introduction In terms of description about the LCA from proving ground, the design engineers provide two modified approaches and we (CAE engineers) compare and analyze the stress distribution and fatigue life between these two schemes. By comparing the calculating results, we can evaluate the designs more quickly, and find out the optimum solution.

6 Model Building and Materials fig 2-1 original design fig 2-2 approach 1 The upper and lower parts of punched lower control arm are made in shell elements and connected with corresponding welding elements as required.

7 Model Building and Materials fig 2-3 approach 2 The arm in approach 2 is a forging part and its model is built in tetrahedral solid elements for the sake of simplicity.

8 Model Building and Materials fig 2-4 MBS Model Multi-body system model of suspension is built in Adams 2005r2, including lower control arm, knuckle, tierod, strut and other major components.

9 Model Building and Materials The material of lower control arm in origin design and approach 1 is X steel, and the material of forging arm in approach 2 is 45# steel. Table 2-1 material data Name Modulus of Elasticity(MPa) Poisons ratio Density(kg/ mm3) Yield Limit(MPa) 45# 2.068E E X steel 2.068E E-6 240~260

10 Loads and Boundary Conditions Loadcase1:vertical 3g(wheel contact patch) Loadcase2:longitude 1.5g(wheel center) Loadcase3:lateral 1g(wheel center) Table 3-1 working conditions and loads applied Working conditions X(N) Y(N) Z(N) Loadcase1 Vertical 3g Loadcase2 Longitudinal 1.5g Loadcase3 Lateral 1g

11 Strength Calculating Results We use MSC Nastran 2005 to calculate the stress by inertial relief method. As the vertical and lateral loads have less effect on the arms, this paper mainly deals with the stress distribution of the arms under longitudinal load applied on wheel center. fig 4-1 original design stress contour fig 4-2 approach 1 stress contour

12 Strength Calculating Results fig 4-3 approach 2 stress contour In approach 2, the stress at its current dangerous place is about 237MPa, but it can still satisfy the design requirements for that material of the forging arm has changed to 45# steel (Yield Limit 335MPa).

13 Strength Calculating Results Table 4-1 stress comparison of different arm designs Origin design(mpa) Approach 1(MPa) Approach 2(MPa) Working condition Crack position Dangerous position Original crack position Dangerou s position Original crack position Dangerou s position Longitude 1.5g

14 Fatigue Analysis of the Arms The fatigue analysis is based on the virtual durability test in which we apply same periodic longitude load on the different arms.

15 Fatigue Analysis of the Arms Fig 5-1 fatigue sine load The load is 1g in +X direction (global coordinate system) to represent braking and 0.7g in -X direction (global coordinate system) to represent driving. This force is a sine function and represents a durability cycle.

16 Fatigue Analysis of the Arms Fig 5-2 original arm life contour Fig 5-3 approach 1 life contour In approach 1, the life exponent rises to 20 at original crack location and to 6.4 from 5.8 at other dangerous areas.

17 Fatigue Analysis of the Arms Fig 5-4 approach 2 life contour In approach 2, the life exponent of forging arm improves more greatly and rises to 7.9.

18 Conclusion MSC software integrates multi-body dynamics, finite-element calculation and fatigue analysis together and has become a virtual production development platform. With the application of these techniques synthetically and based on our engineering background, we can do compared analysis of different designs during development process very quickly and find the best solution.

19 Conclusion By guiding our design engineers in making new products, we help our company to shorten the development period and reduce design costs. CAE, definitely, will take a more important role in the whole product development process.

20 Yi Zhou and Dong Ma