Multi-criteria optimization of test rig loading programs in fatigue life determination

• We present an optimization problem modeling the best design of the test rig.
• Introducing moments at the attachments dramatically improves design of the test rig.
• Numbers of the stress cycles can be fixed without significant change in the result.
• Load signals should have at least 3 blocks to achieve appropriate results.
• Fully reversed loading does not provide acceptable quality of approximation.

Designing good test rigs for fatigue life tests is a common task in the automotive industry. The purpose of this work is to show that the problem to find an optimal test rig configuration and actuator load signals can be formulated as a mathematical program. A new optimization model that includes multi-criteria, discrete and continuous parts is introduced.Block structure of the load signals is assumed from the beginning, which highly reduces complexity of the problem without deterioration of the overall result. Also, actuators’ alignment is optimized, which makes it possible to take bending moments into account and thus improve quality of the test. As a result, the new model gives significantly better results, compared with the other approaches in the test rig optimization.