Mesoscopic Defects of Forming and Induced properties on the Impact of a Composite Glass/Polyester

Abstract

Forming processes induce residual deformations on the reinforcement and sometimes lead to mesoscopic defects, which are more recurrent than macroscopic defects during the manufacture of complex structural parts. This work contributes to the experimental study of the effect of mesoscopic buckles defect and shear deformation of the reinforcement, which result from forming, on the low velocity impact behavior of a composite laminate. The material studied is a glass/polyester composite with three layers of mat and one layer of taffeta fabric. To assess the properties induced on the final composite, plates with different amplitudes of calibrated defects and deformations were manufactured. First, the healthy material, which serves as a reference, was subjected to three levels of impact energy to observe the evolution of its behavior and damage mechanisms. Results of the impact tests and observations performed on the materials with calibrated defects identified a negative effect of buckling on elastic parameters and revealed greater damage relative to the healthy material. The reinforcement shear had a beneficial effect on the impact properties of the laminate, which was attributed to the increase in local fiber density.