Effect of Thermo-Mechanical Gradient on the Damage Mechanisms of Composite Laminates
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TECHNICAL ARTICLE—PEER-REVIEWED
Effect of Thermo-Mechanical Gradient on the Damage Mechanisms of Composite Laminates Meryem El Moufari . Larbi El Bakkali
Submitted: 9 April 2017 / in revised form: 28 July 2017 / Published online: 29 August 2017 Ó ASM International 2017
Abstract The main purpose of this work is to characterize and discriminate the respective roles of the thermomechanical gradient in the damage mechanisms of composite laminates used in aeronautics in order to understand the initiation and evolution of damage modes. For this purpose, a finite element model of compact tension specimen with a series of virtual crack closure techniques is achieved in order to evaluate the energy release rate of transverse matrix cracking in composites. The continuum mechanics approach in combination with Hashin’s damage criterion is adopted to describe initiation and evolution for each damage mode proposed for carbon/epoxy laminates. The good agreement between the numerical results and experiments in other available literature shows the validation of the analysis and developed model in this paper. Keywords Composite laminates Continuum mechanics Thermo-mechanical loading Finite element analysis
Introduction The increasingly widespread use of fiber-reinforced polymer-matrix composites for aeronautical applications with a long service life led to examining the couplings between mechanical loading and a superimposed variation in temperature due to the aerodynamic heating that results from supersonic cruise. Further, for most structural applications
M. El Moufari (&) L. El Bakkali Modeling and Simulation of Mechanical Systems Laboratory, Faculty of Science, Abdelmalek Essaadi University, M’hannech, 93002 Tetouan, Morocco e-mail: [email protected]
in current aircraft designs, polymer composites were considered for a wide range of applications in other areas where higher temperatures are encountered. Such applications cover many parts on and around the aero-engine in current usage and will cover several airframe structural components in future high-speed transport aircraft. In addition to mechanical load conditions encountered in flight, leading edges of aircraft structures are subjected to severe thermal structural loading conditions during the engine mission cycle. When variation in load and temperature occurs simultaneously, it is referred to as thermomechanical fatigue (TMF) which is expected to be one of the most severe service conditions. The most damaging stresses and strains are those induced by the steep thermal gradients, which occur during the start-up and shutdown transients due to the large difference in the coefficient of thermal expansion between the matrix and fibers [1]. Thus, there is a need to understand the thermo-mechanical influence on the damage onset and evolution in composite materials, and then understand the thermal expansion effects and thermal expansion mismatches between adjacent structures. The damage initiation and evolution process in composite materials is one of the impor
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