Enabling Experimental Impulse-Based Substructuring through Time Domain Deconvolution and Downsampling

TL;DR

This paper demonstrates an experimental impulse-based substructuring method that accurately predicts shock responses in rods by combining time domain IRF estimation with filtering and downsampling, overcoming previous experimental challenges.

Contribution

It introduces a novel experimental application of impulse-based substructuring using time domain deconvolution and downsampling, improving shock response prediction accuracy.

Findings

Successful experimental prediction of shock responses using IBS

Effective use of low-pass filtering and downsampling in time domain

Overcomes previous limitations of IBS in experimental settings

Abstract

Dynamic substructuring, especially the frequency-based variant (FBS) using frequency response functions (FRF), is gaining in popularity and importance, with countless successful applications, both numerically and experimentally. One drawback, however, is found when the responses to shocks are determined. Numerically, this might be especially expensive when a huge number of high-frequency modes have to be accounted for to correctly predict response amplitudes to shocks. In all cases, the initial response predicted using frequency-based substructuring might be erroneous, due to the forced periodization of the Fourier transform. This drawback can be eliminated by completely avoiding the frequency domain and remaining in the time domain, using the impulse-based substructuring method (IBS), which utilizes impulse response functions (IRF). While this method has already been utilized successfully for numerical test cases, none of the attempted experimental applications were successful. In this paper, an experimental application of IBS to rods considered as one-dimensional is tested in the context of shock analysis, with the goal of correctly predicting the maximum driving point response peak. The challenges related to experimental IBS applications are discussed and an improvement attempt is made by limiting the frequency content considered through low-pass filtering and downsampling. The combination of a purely time domain based estimation procedure for the IRFs and the application of low-pass filtering with downsampling to the measured responses enabled a correct prediction of the initial shock responses of the rods with IBS experimentally, using displacements, velocities and accelerations.