During the course of designing a product with severe environment requirements, we usually execute a number of analyses as an integral part of the development process.
Early in the program, we perform a quick system-level dynamics analysis of the printed circuit modules to determine their natural frequency, optimize the appropriate mounting method and ascertain how thick the boards need to be to be compatible with safe excursions of the PC board and to prevent fatigue failures in the individual components.
We also take a look at the thermal dissipation of the chassis to determine what thermal management approach is appropriate, identify potential problem areas and optimize the thermal paths in the chassis design to meet the reliability requirements.
Once the system-level thermal and dynamic strategies are decided upon, we then proceed with the detail design. Once the detail design is mature, we then revisit the chassis stress, thermal and printed circuit module dynamics with a detailed FEA analysis as appropriate. If there are thermally sensitive components in the unit, we also perform a thermal analysis on individual boards to verify that the maximum temperature of the individual components fall within an acceptable range.
We use Sauna MS, a system level thermal application to identify potential problem areas in our preliminary designs. For detailed thermal, stress, natural frequency and transient analysis we use Inventor Simulation Mechanical (ALGOR), ANSYS and Cosmos-M. We also utilize a proprietary fluid flow program for heat exchangers.