After an extensive evaluation General Motors has recently purchased a multiple-seat license of LMS OPTIMUS - the software that enables any CAE engineer to automatically generate, analyze, explore, and track design alternatives. In principle, OPTIMUS can work with any legacy simulation software program. It automates the generation of input files and the extraction of the results - there is no need to write specific interface programs - so, at a stroke, one of the drudges of engineering optimization has been eliminated.
Within General Motors, LMS OPTIMUS has found many applications. Its potential can extend to crash simulation, multi-body kinematics and dynamics simulation, component design, static and dynamic analysis, and vibro-acoustic simulation and optimization.
Don Jones, a Staff Research Scientist at GM R&D, has worked closely with LMS to develop a protocol for linking OPTIMUS with user-provided optimization codes. Using the first version of the developed protocol, OPTIMUS was successfully linked with a GM-developed optimization algorithm called “DIRECT.” Mark Neal, a Staff Research Engineer at GM R&D, and Ting-Tsai Tseng, a Design Engineer at GM Truck, then used the OPTIMUS/DIRECT combination, as well as, response surface methods, to solve an engineering optimization problem in the area of occupant dynamics crash simulation. The simulation code, called MADYMO, uses lumped parameter models to simulate how crash-test dummies interact with passive and active restraint systems.
The DIRECT algorithm does not require derivatives or starting points and, on low-dimensional problems, typically requires fewer simulation runs than other algorithms. Mark points out, “The efficiency of the optimization algorithm is important. Evaluating potential designs is compute intensive since more than one simulation needs to be performed to evaluate each design point. By using OPTIMUS, we were able to set-up our optimization problem quickly and explore the design space for different dummy sizes and different impact velocities in the same run, which has saved us a tremendous amount of time and compute resources.”
Shih-ching Huang, Senior Project Engineer of GM Truck Group, is using OPTIMUS to optimize the location and stiffness of the engine mounts in order to increase passenger comfort in terms of vibration and acoustics. “The automation that OPTIMUS offers to our existing simulation programs is unique and has allowed us to easily generate many more design alternatives than we could ever do before” expresses Shih-ching. “Exploring these alternatives to determine the most promising is easily made through the graphical post-processing capabilities and the Numerical Optimization module. The Design of Experiments (DOE) module minimizes the time and computer resources that are needed to complete the task. Interfacing OPTIMUS to our existing simulation software took only of a few hours, without requiring us to write any interfacing program.”
