Crack propagation in aluminum–nomex panels : experimental and numerical approach

Abstract EN

This paper analyses the damage tolerance behavior of an aluminium–Nomex sandwich panel subjected to shear load.

The panel was tested inside a dedicated picture frame shear test fixture in order to apply a pulsating fully shear load.

An artificial crack was created at the center of the panel on one of the skins.

In order to acquire the propagation data, two crack propagation gauges (CPG) were applied at the apex of this artificial crack.

Two finite element (FE) models of the panel were created in order to analyze the stress intensity factor (SIF) parameter of fracture mechanics, during propagation, using two different numerical approaches to schematize the crack propagation.

The analytical approach is based on a classic FE method, with a complete 3D model and manual propagation of the crack, and a dedicated program with automatic propagation on a 2D model (with a simple numerical correction to take 3D behavior into account).

Comparison of the experimental data and the analytical results with existing propagation data (NASGRO) for the 2024 aluminum alloy of the skin, showed good agreement.

Thus, FE models may also be used to perform damage tolerance evaluation for complex sandwich panel constructions.