Application of Simulation in Improving Vibration Reliability of Steering Control Unit

Electronic control units in field use are exposed to a wide range of environmental loads like vibration, temperature, humidity and some combined loads like vibration with temperature. This paper discusses measurement, simulation and testing, where vibration measurements are carried out on plastic cover with accelerometers before the start of the validation. Once the vibration test is finished it is found that Ceramic Chip Capacitor (C Chips) at printed circuit board (PCB) bending location show errors at high temperature functional test but the C chips do not show an error at room temperature. A FE model is built using ANSYS Workbench and Acceleration power spectral density (PSD) responses from simulation are validated for resonance frequency. The damping with material properties at room temperature is validated with measurements carried out before validation. Further simulations are carried out with the temperature dependent properties to find out the strains on PCB at the three C chips out of which one C chip fails at 100 °C and other two do not. Idea is to find out the temperature at which strains on PCB at top C chip will be less than strains obtained at bottom C chip at 100 °C, as the bottom C chip had passed at 100 °C but not the top C chip. There are three simulations carried out with temperature properties for 100 °C, 80 °C and 70 °C to get a trend of strain variation with temperature and the highest temperature was made use in validation that resulted in successful pass.