Identification of damage mechanisms in a metal-matrix composite material via digital volume correlation and finite element model updating

A 3D experimental and numerical investigation of the damage mechanisms induced by compression in a metal-matrix composite is presented. The investigated composite is a simplified version of those typically used for heavy-duty brake linings, comprising only nine constituents. The analysis combines laboratory in situ X-ray computed tomography (XCT), image volume correlation (DVC), as well as image-based finite element method (FEM) paired with an inverse identification approach known as finite element model updating (FEMU). The combination of XCT and DVC allows the rationalization of the mechanisms controlling strain localization and damage accumulation within the heterogeneous metal-matrix. The damage mainly occurs in the form of fractured material within thin cell-walls occurring between large graphite G2 particles. In addition, the herein developed FEMU approach enables the identification of the compressive elastic moduli of the two defined key constituents (i.e., Matrix --where eight of the nine constituents are lumped-- and graphite G2 particles) controlling the macroscopic compressive behavior, as well as the prediction of the damaged regions within the Matrix. It is emphasized that an implementation of the damage mechanisms within the FEMU is essential for a reliable numerical description of the compressive response of the Matrix.