7 A Workflow Combining Ansys Sherlock, Icepak, and Mechanical to Evaluate the Reliability of Electronic Systems
Figure 11: Thermal Gradients in Mechanical.
Figure 12: Mechanical Pothole Shock Results.
13. We run an FEA analysis to quantify the effect of the PCBA being stressed when the vehicle encounters a pothole. The simulation
was conducted assuming the PCBA was operational, so the thermal gradient was first incorporated as a pre-load prior to the
pothole shock load application.
The loading from the pothole was approximated with a 25G, 10ms half-sine pulse applied in the negative out-of-plane direction.
The resulting peak PCBA strains are shown below.
14. The FEA results from Mechanical are then imported to Sherlock, and the strains are used to predict reliability
(probability of failure).
Again, our hypothesis is that the autonomous vehicles will hit 3 potholes per hour, while operating 15 hours per day for 2 years. In
this analysis, even with the inclusion of the thermal expansion strains, none of the components are predicted to be failure risks. The
Galileo board is a relatively small, thick PCB, making it stand up fairly well to shock events.
Thermal Expansion and
Resulting Strain
Pothole Shock Strain with
Thermal Strains
