Frequency Domain Structural Synthesis Applied to Quasi-Static Crack Growth Modeling

Young W Kwon,Joshua H Gordis

doi:10.1155/2009/978437

Abstract

Quasi-static crack growth in a composite beam was modeled using the structural synthesis technique along with a finite element model. The considered crack was an interface crack in the shear mode (i.e. mode II), which occurs frequently in the scarf joint of composite structures. The analysis model was a composite beam with an edge crack at the midplane of the beam subjected to a three-point bending load. In the finite element model, beam finite elements with translational degrees of freedom only were used to model the crack conveniently. Then, frequency domain structural synthesis (substructure coupling) was applied to reduce the computational time associated with a repeated finite element calculation with crack growth. The quasi-static interface crack growth in a composite beam was predicted using the developed computational technique, and its result was compared to experimental data. The computational and experimental results agree well. In addition, the substructure-based synthesis technique showed the significantly improved computational efficiency when compared to the conventional full analysis.

Highlights

The failure analysis of large-scale structural systems such as aircraft and ships is a computationally demanding task, and is frequently pursued on a component basis
The computational demand is significantly increased by the presence of composite materials due to the need to include through-the-thickness computations for ply failure
We explore the use of substructuring techniques in the failure analysis of structural systems

Summary

Introduction

The failure analysis of large-scale structural systems such as aircraft and ships is a computationally demanding task, and is frequently pursued on a component basis. Y.W. Kwon and J.H. Gordis / Frequency domain structural synthesis applied to quasi-static crack growth modeling. We will develop a hybrid frequency domain substructure/crack growth analysis methodology for an interface crack in a composite structure. This will allow those portions of the structures not containing a crack to be eliminated from the analysis, except for the coupling DOF. An example problem is provided for quasi-static crack growth in a composite beam For this example, both computer modeling results (traditional full-up analysis and the substructuring methodology) are compared to the experimental data.

Frequency domain substructuring

Finite element modeling for crack growth

Example problem

Findings

Conclusions