Join the Southern Polytechnic College of Engineering and Engineering Technology for our biweekly research seminar series! This week, Dr. Vijay Goyal, an aerospace engineer with 27 years of professional experience in teaching, research, and stress analysis, as he leads a lecture and conversation on damage analysis. 

Abstract

Composite structures are susceptible to inter/intraply damage in the form of delamination, matrix cracking, and fiber fracture. This effort aims to develop, evaluate, and enhance methods to computationally predict damage initiation, progression, and failure of postbuckled composite hat-stiffened panels subjected to static and fatigue axial compressive loading. The specimens had two types of embedded damage: Teflon (PTFE) inserts and initial barely visible lowvelocity impact. The novel “fatigue R-curve” (not fatigue loading Rratio) is implemented into the Abaqus VCCT fatigue solver via a user-defined subroutine, improves the cycles to failure prediction, and is being considered for implementation by Dassault Systèmes Simulia. VCCT is shown as a viable alternative when prior knowledge exists for the damage initiation location and the predominant intralaminar failure. EST/CZM proved to capture the debonding initiation and growth patterns accurately. Hence, for a quick assessment with prior knowledge of the damage initiation region, the VCCT suffices. However, EST/CZM could benefit the engineer with a more complete and comprehensive failure mode analysis, thus outweighing the computational cost. Finally, the work shows that postbuckled composite panel design is viable, although it requires further study of different loading and boundary condition patterns.