A Method of Accelerating Durability Tests by Pseudo Damage Editing 2013-26-0138
Arriving at an accelerated durability test cycle either for a laboratory simulation or for an FE-based fatigue simulation is not an easy task. The loading spectra over the entire life span or desired validation cycle needs to be synthesized and the resulting signal is to be used for driving a rig or for Computer Aided Engineering (CAE) simulation, as the case may be. Any structural durability evaluation essentially involves multiple measurements involving strain, acceleration, displacement, force-all of which directly or indirectly are a measure of fatigue damage on the structure.
Multi channel dynamic events (time domain based) comprising strain signals can be accelerated by damage-editing, but what if the input time histories are not strains but are displacements, accelerations and forces? A directly “non damaging” parameter like displacement or acceleration or force signal makes an accelerated test synthesis not very easy.
The aim of this paper is to provide a procedure for deriving an accelerated durability test cycle by using an acceleration or a displacement signal, which otherwise is a straight forward process when a strain signal is used.
This paper presents a hybrid method which uses the frequency domain techniques for stochastic events analysis (shock response spectra, extreme response spectra, fatigue damage spectra, test tailoring) and dovetails it into a tailored time series damage editing process for arriving at an accelerated durability test by using an acceleration or displacement signal as the input. This process can be applied to test cases where no strain response on the vehicle structure is available, but an input acceleration or displacement from a road forms the measured input.