EFFECT OF LOADING PATH AND SPECIMEN SHAPE ON INVERSE IDENTIFICATION OF ELASTIC PROPERTIES OF COMPOSITES

摘要

This paper presents a methodology for using sensor-generated data from multi-degree-of-freedom mechatronic loading systems to identify the elastic moduli of a composite laminate material system. This is done not to demonstrate the method itself but rather to study how various features of the experimental and analytical procedure can affect the identification process. The analytical formulation of the identification problem is described first given the geometry of a test specimen and a loading path. The concept of singular value decomposition (associated with pseudo inversion factorization) is introduced for the purpose of parameter identification as it applies to the elastic moduli. Also, the concepts of distinguishability and uniqueness are introduced to evaluate the quality of parameter identification. The analysis is performed on a continuum model basis in order to evaluate if the proposed technique can work for specimens of arbitrary shape. Elastic coefficients were identified using pseudo-experimental (numerically synthesized) data created by finite element analysis (FEA) and the effect of the introduced distinguishability and uniqueness on the identification was investigated through several numerical examples. The effects of the form of the chosen multidimensional loading path(s) and the shape of the specimen on various features of the inverse identification process related to the elastic moduli parameter estimation are also determined. The results of the numerical studies demonstrate the efficacy of the proposed methodology and suggests subsequent avenues for optimizing the specification of the loading path both a priori and in real-time.