Investigation of the mixed-mode fracture in delamination tests: numerical simulations using cohesive zone and partitioning methods

Josip Kačmarčik

doi:10.17559/tv-20140723162324

Abstract

Delamination (fracture) tests have been numerically investigated using various cohesive zone properties. The test utilises asymmetric and symmetric double cantilever beam specimens loaded with bending moment. Energy release rate contributions from mode I and mode II fracture are calculated using a global and local approach. Mode-mixities results are presented and analysed. The numerical partitioning results for different configurations are compared to two analytical partitioning theories, namely, after Williams and after Hutchinson and Suo. Opposite to these theories, partitioning is observed to be dependent on cohesive zone properties.

Highlights

Interlaminar fracture is one of the most important failure modes for many modern materials arranged in layers
Mixed-mode fracture is often observed in delamination, where fracture toughness can be vary depending on mode-mixity, i.e. amounts of different fracture modes are present
To calculate contributions from mode I and mode II fracture one can employ analytical or numerical partitioning methods, each of which suffer from a number of uncertainties and can produce different results depending on choice of a theoretical approach, numerical model, etc

Summary

Introduction

Interlaminar fracture is one of the most important failure modes for many modern materials arranged in layers. Mixed-mode fracture is often observed in delamination, where fracture toughness can be vary depending on mode-mixity, i.e. amounts of different fracture modes are present (mode I and mode II are mostly considered). It is of great importance for design consideration of these materials to define the interlaminar toughness for full range of mode-mixities, from pure mode I to pure mode II fracture. The pure mode I and II fracture toughness calculations from the experimental results are pretty much straightforward, there is much confusion about analysis of test configurations with mixed mode fracture. To calculate contributions from mode I and mode II fracture one can employ analytical or numerical partitioning methods, each of which suffer from a number of uncertainties and can produce different results depending on choice of a theoretical approach, numerical model, etc

Objectives

Results

Conclusion