FEA of Heavy Vehicle Bracket for an Excitation Load

Transcription

1 FEA of Heavy Vehicle Bracket for an Excitation Load Mr. Nishikant Thonte Design Engineer Autoline Design Software Ltd. Bhosari, Pune, Maharashtra Mr. Surendra Ketkar Design Engineer (CAE) Autoline Design Software Ltd. Bhosari, Pune, Maharashtra Mr. Praveen Patil Team leader Autoline Design Software Ltd. Bhosari, Pune, Maharashtra Mr.Nagarajan Laxmanan CEO Autoline Design Software Ltd. Bhosari, Pune, Maharashtra. Abstract The objective of the project is to analyze the bracket for a given excitation load. The FEA model consists of shell elements and the mesh is generated with the specified quality criteria. Further the FE model is provided with elemental properties, material properties, loads and boundary conditions. The connections in between locking bracket, mounting bracket, support bracket and clamping strap are given by RBE2 elements. The mass representation on the bracket is done by 1D mass element (RBE 3). The analysis consists of modal analysis and dynamic analysis. The solver used for the analysis is Radioss and further the optimization has been done with OptiStruct. The results are visualized in HyperView. Introduction: FEA Analysis was made on heavy vehicle bracket; the purpose of the study is, 1) To reduce the stress concentration at specific location. 2) To optimize the mass of the bracket assembly. To carry out above process Altair HyperWorks suite has been explored. Objective: Modal And Dynamic analysis for optimal design of bracket. Model: Bracket modeled with shell elements. Loading: An Excitation load 1.7 G in X direction and 4.1 G in Z direction. Boundary conditions: Constrained at locations as shown in figure. (All 6 DOF are locked). Material Used: Steel e410 Modulus Of elasticity: 1.85e5 N/mm2, Poisson s Ratio: 0.28 Density: 7.85e-9 TONNE / mm3, Yield Strength: 250 Mpa Ultimate tensile strength: 410Mpa 1

2 Constrained in all Directions Fig 1: Base model of bracket The Base line design Model consists of continuous Base plate which was heavy in mass. Fig2: Base Plate So the main concern was to reduce the mass of plate with optimum strength. The base plate is modified as shown below in fig 4. 2

3 Case study on proposed model 1 of Bracket Constrained in all directions Excitation load 2.14 G in X, 4.13 G in Z direction. Fig3: proposed model 1 of bracket. Fig 4: modified base plate. 3

4 Modal analysis Results: Mode no Frequency in Hz (Z-Direction) ( X-Direction) (X-Direction)

5 Stress plot Results: Vonmises stress 6 Hz frequency in Z-Direction MAX.STRESS = 350 Mpa Vonmises stress 13 Hz frequency inx-direction MAX.STRESS = 364 Mpa The modification is done with the base plate. The plate is divided in to three small plates which helped to reduce the mass of the bracket by 10%. But the stresses are more than the ultimate strength of the material at the bolted portion.so the final design as shown in fig 6 is made with the added ribs instead of plane surface which helped to improve the strength with the reduced mass.2 plates of E34 material are added at the weaker portion in order to reduce the localized stress at bolt region. 5

6 Case study on proposed Final model of Bracket Constrained in all directions 2 Plates of E34 and thickness 5mm are added Fig 5: proposed final model of bracket. 6

7 Fig 6: Final base plate Modal analysis Results: Mode no Frequency in Hz (Z-Direction) ( X-Direction) (Z-Direction)

8 Stress plot Results: Vonmises stress Hz frequency in Z-Direction MAX.STRESS = 209 Mpa Vonmises stress Hz frequency in X-Direction MAX.STRESS = Mpa 8

9 Benefits Summary: Tremendous Benefits are achieved in process validation as mentioned below: No. of trials were reduced to prove the product while sample submission, Overall tool modifications reduced and hence the cost of modifications, One time sample submission was easily achievable, Confident level raised drastically in new product development We can achieve the mass reduction. Future Plans: 1. We will run the FEA analysis for different design models. 2. Select best optimized model by referring FEA Results. 3. Take the practical testing for optimized model. This will save time as well as total cost. Conclusion: From this FEA Analysis, we have optimized the mass value less than the base model value. The FEA results as well practical testing are identical. Also we can see that the strength of the bracket is improved by adding the beads in weaker sections. 9