Identification of the material parameters of laminated plates

Abstract

In this chapter, a scheme to identify the material parameters of laminated plates by mathematical optimization has been presented. The object function of the optimization is defined as the difference of measured frequency and computed frequency by finite element analysis. The nonlinear optimization algorithms are adopted and the sensitivity analysis of material parameters on structural eigenvalues are deduced. Finally, a numerical example is presented to show the feasibility of the presented scheme. For the structure members, consisting of isotropic material, the material properties can be measured by rather simple routine experiments of typical specimens. For the composite material, the heterogeneity and anisotropy make the identification of material properties more complicated. The material parameters measured by simple specimens would not be consistent with the actual parameters of the material in a composite structure. Therefore, the experimental and numerical combined approach has been developed for some kind of identification problems. A scheme to identify the material parameters of composites by combined stress field measurement and finite element analysis has been suggested, including a scheme to identify the elastic parameters of laminated plates by the frequencies of free vibration. Furthermore, some authors have presented the methods to identify the damage location by modal experiments.