Notched CFRP laminates under vibration

Abstract

This paper deals with the experimental and theoretical analysis of damaged and undamaged Carbon Fiber Reinforced Polymer (CFRP) laminate elements under free vibration. CFRP laminate specimens were experimentally investigated using a mechanical apparatus capable of simulating hinge conditions at the edges of simply supported laminate beams. Damage in the CFRP laminates subjected to testing was due to double rectangular notches on different sections of the specimens with varying increases in width determining local reduction of bending stiffness with effects on dynamic response. Shown herein are the envelope of Frequency Response Functions (FRFs) obtained through dynamic testing and the changes of natural frequency values are related to the damage degree of CFRP laminates. A theoretical model, based on the assumption that an elastic rotational hinge concentrated at the axis of a notch may be assumed to describe damage analytically, was developed for an analytical study of damaged CFRP laminates under vibration. Theoretical frequency values are compared with those obtained through tests and finite element analysis. The availability of the theoretical model on the basis of the data collected is discussed.