Damage Mechanisms in Unidirectional SiC/Ti Composites under Transverse Creep Loading: Experiments and Modeling

Abstract

The damage mechanisms under transverse creep of two unidirectionalmetal matrix composites are investigated. This paper is based on a two-scale approach, and on experimental and numerical studies. On the macroscopic scale, the global response of the composite subjected to aconstant transverse load is analyzed. On the microscopic scale, the influence of each component (matrix, fibre and interface) on the global behavior is investigated. In the experimental part of the study, creep tests have been performed at different temperatures under vacuum, and scanning electron microscope (SEM) observations have allowed the investigation of the damageevolution under different applied loads. In the numerical work, the creep tests were simulated on a representative unit cell using the finite element method and taking into account the various nonlinearities (matrix viscoplasticity coupled with interface damage). The experimental and numerical results show that the global behavior of the composite depends on the local interfacial behavior. Two domains are evidenced as a function of the applied stress, a critical stress being thus determined. Below the critical stress, the interfaces remain undamaged, leading to a low creep rate and a long duration test. Above the critical stress, the interfaces are totally debonded, thereby increasing the secondary creep rate and leading to a possible specimen failure.

Multiscale Methods for Composites: A Review

“…Later on, Pottier [148] has used the same methodology for long fibre composites and has introduced an anisotropic macroscopic damage. To have a damage directly at the heterogeneities scale, Carrère et al ( [34,36]) proposed an extended formulation. To that end the extension of TFA proposed by Chaboche et al [34] is used to take into account the non-linearities due to changing elastic local behaviour (temperature or damage induced).…”

“…To have a damage directly at the heterogeneities scale, Carrère et al ( [34,36]) proposed an extended formulation. To that end the extension of TFA proposed by Chaboche et al [34] is used to take into account the non-linearities due to changing elastic local behaviour (temperature or damage induced). Let us consider the following localisation rule: ε r = A r : + s D rs : L s : ε GE s (97) with ε GE r = (ε th r + ε p r + ε d r ) (see Sect.…”

Multiscale analysis of SiC/Ti composites

“…Description of the constituents behaviour and of the appropriate elementary cell can be found in [3] (for visco-plastic matrix) and in [2] for polycrystalline matrix. For example, it is possible to perform simulations, such as:…”

“…In a previous study, Carrere et al have shown that it is necessary to take into account the effects of the interface bond strength, of the internal thermal stresses and of the local texture of the matrix via a polycrystalline aggregate model [2]. In fact, transverse creep tests have been performed on a SiC/Ti composite under vacuum at a temperature of 500 • C. These tests, reported in a previous paper [3], have revealed classical creep curves with the three characteristic stages: primary, secondary and tertiary. Using a three-scale approach (from the grain scale to the composite scale), it has been shown that the global response strongly depends on the local fibre-matrix interface behaviour and on the textured polycrystalline nature of the matrix.…”

Progress in shakedown analysis with applications to composites

“…Experimental and numerical observations show that the global behaviour of fibre-reinforced composites depends on the local interfacial damage. Following Carrère et al [12] two domains can be evidenced as a function of the applied stress. Below the critical stress, interfaces remain undamaged, and above, interfaces are totally debonding.…”