Prediction of dynamic strain using modal parameters

Abstract

The relentless pursuit of greater productivity and lower maintenance costs, allied to the development of optimized products, has led to increasing concerns regarding fatigue failure. This scenario reinforces the importance of monitoring dynamic stress and strain in structures and machines subjected to vibration. For this purpose, several methods that use vibration parameters have been developed to predict dynamic stress and strain. By these methods, dynamic strain is predicted basically through the spatial derivation of displacement responses. In this paper, these methods are classified and compared. The strain prediction methods are evaluated, particularly: curvature analysis applied to the determination of beam strain; the strain displacement transformation matrix and hybrid modal analysis. The methods of hybrid modal analysis and strain displacement transformation matrix were evaluated based on numerical simulations using Frequency Response Functions and Transmissibility, while an experimental evaluation was made to determine the strain in an aluminum beam based on acceleration signals and the finite difference method. The simulations and experiments yielded satisfactory and promising results for the determination of dynamic stresses and strains on surfaces, thus providing an overview of how these methods can be applied.