Drop Test Simulation of Automobile Alternator using Altair RADIOSS

Transcription

1 Drop Test Simulation of Automobile Alternator using Altair RADIOSS SivaSankar Reddy. A Sr. Engineer CAE Valeo India Private limited Sholinganallur Chennai India Thangavelu. C Engineering Manager Valeo India Private limited Sholinganallur Chennai India Karthic Sethuraman Engineering Manager Valeo India Private Limited Sholinganallur Chennai India Keywords: Automobile alternator, Drop test, Altair RADIOSS, Abstract An alternator is an electromechanical device that converts mechanical energy to electrical energy during operation. Alternators are used in modern automobiles to charge the battery and to power the electrical/electronic system when its engine is running. Proper functioning and efficiency of alternator is very important in automobile for the functioning of electric devices. The power needs to be transmitted from origin point to different locations, to do this there is specific take off live terminal. This take off live terminal must be prevented from risk of touching other system components. The main aim of this study is to understand the behavior of assembly and to check the stiffness of parts when it is dropped from certain height. The initiation of this study was started after observing the failure of part in field drop test. This study includes simulation on initial design and on modified designs. Altair HyperMesh, HyperCrash and RADIOSS are used to perform this study. Introduction: Automobile alternator is a key component in an alternator. The behavior and stiffness of alternator is checked when it is dropped from certain height. Simulation is performed on initial design to check the critical regions and results are analyzed. Based on initial simulation results design improvements was carried and simulations are performed. Process Methodology: Alternator assembly consists of different sub assemblies like rotor assembly, stator assembly, regulator assembly, and rectifier assembly, front, rear brackets and rear cover. FE Simplifications: Alternator assembly is complex in nature because of its various subassemblies. Simplifications were done on various parts and few assemblies considered as lumped masses at the COG locations. The parts like cover and electronic unit which are critical for study were considered with any design simplifications. Preprocessing: Altair HyperMesh and HyperCrash is used. Solver: Altair RADIOSS. Post Processing: Altair HyperView and HyperGraph. Simulate to Innovate 1

2 Figure 1: Alternator complete FE model. Parts considered for simulation: Figure 2: Rear Bracket with Screws Simulate to Innovate 2

3 Figure 3: Simplified part of electronic assembly Figure 4: Front Bracket Interface definitions: The contact surfaces needed for the accurate definition of the interfaces are created in HyperCrash using self Impact option. Contact Interfaces of Type 7 is created and friction is depending upon the contact status of the interface, appropriate minimum distance for impact is carefully chosen. Control Cards and Engine Settings: Appropriate control cards for controlling strain formulation are used to ensure that the stable time increments for the solution are not abruptly low. All required output controls are activated to capture stress, plastic strain and deformation at desired time intervals. History output of Global variables like Internal energy, Kinetic energy, Hourglass energy and Total energy are requested to monitor the accuracy of the solution. Appropriate frequencies are defined for writing out results of field variables, global variable and, restart files. Eight processors are used for the engine calculation using HP-MPI in Windows 64 bit operating system. Simulate to Innovate 3

4 Loading Conditions: Initial velocity is applied to assembly. Figure: 5 Initial design Figure 6: Improved Design Results & Discussions: Deformation Plots: Figure 7: Initial Design Figure :8 Improved Design Simulate to Innovate 4

5 Stress Plots: Figure 9: Initial Design Figure 10: Improved Design. Stresses developed in the initial design are very high compared to modified design. Benefits summary: 1. User Friendly mesh definition methods in Altair HyperMesh 11.0 has resulted in reducing the preprocessing time considerably. 2. HyperMesh made it easy and quick to modify the mesh from initial to modified geometry which resulted in considerable time saving. 3. Ease of defining contact, User friendly Penetration detection and correction methods in Altair HyperCrash 11.0 has also helped in a reduction of time further. 4. The revolutionary Token based Altair licensing ensures that the engineer can prepare a new orientation model in Altair HyperCrash when the RADIOSS engine solution for another orientation is in progress or read results of a calculation in HyperView or HyperGraph that is already completed. Challenges: 1. Simplification of geometry to have quick results. 2. Selection of appropriate element type, size and control cards for element properties to ensure a manageable stable time increment for solution. 3. Resolution of initial penetration in contact interfaces. 4. Arriving at an optimal calculation time (total time of impact simulation) to ensure appropriate stabilization of Global variables (Internal and Kinetic energy) and minimize calculation errors. Conclusions: Drop test simulation of alternator assembly using Altair HyperWorks tools has given a considerable confidence to the Research and development team in the ability to predict the robustness of the design at the early phase of product development and identify improvement opportunities if any for future concepts. Simulate to Innovate 5

6 Altair tools helped us to find the design solution by showing the critical location on the initial design and helped us to launch updated designs quickly. ACKNOWLEDGEMENTS The authors would like to thank Mr.Sriram.G, R&D Director, Valeo India Private Limited for his constant support in documenting this study and sharing it with the CAE community in the Automotive Industry [1] Altair HyperWorks11.0 Online documentation. REFERENCES Simulate to Innovate 6