Fatigue damage model for injection-molded short glass fibre reinforced thermoplastics

Abstract The present paper is a contribution to the phenomenological modelling of fatigue non-linear cumulative diffuse damage in short glass fibre reinforced thermoplastic matrix composites. In such materials, fatigue damage kinetic exhibits three stages, namely: (i) material softening and damage initiation, (ii) coalescence and propagation of micro-cracks and (iii) macroscopic cracks propagation and material failure. The proposed model is built in the framework of the continuum damage mechanics and aims at predicting these three stages of the damage evolution. This model is based on the approach initially proposed by Ladeveze and Le Dantec [Ladeveze P, Le Dantec E. Damage modelling of the elementary ply for laminated composites. Comp Sci Technol 1992;43:257–67]. It extends the previous approach and takes into account the important stiffness reduction observed during the first damage stage. The above is modelled by the integration of a combined Norton-like power law and an exponential law expressing the damage rates as a function of the associated thermodynamic dual forces. The model has been formulated in terms of strain energy, so that makes easy its numerical implementation into the finite element code Abaqus/Standard through a user defined material subroutine UMAT. Numerical simulations are performed on a short glass fibre reinforced thermoplastic described by a given set of damage parameters. Damage evolutions predicted by the developed model reproduce well those observed for this kind of composites under cyclic loading. A parametric study is performed to understand the effects of the model parameters on the damage accumulation and their sensitivity on its kinetic. The sensitivity study would be useful since it contributes to optimise the ongoing experimental procedure aimed at identifying the damage model parameters.

[1]  S. Mahadevan,et al.  Multiaxial high-cycle fatigue criterion and life prediction for metals , 2005 .

[2]  Fabrice Pierron,et al.  Direct identification of the damage behaviour of composite materials using the virtual fields method , 2004 .

[3]  W. Van Paepegem,et al.  A new coupled approach of residual stiffness and strength for fatigue of fibre-reinforced composites , 2002 .

[4]  Theodore P. Philippidis,et al.  Residual strength after fatigue in composites: Theory vs. experiment , 2007 .

[5]  M. Benzeggagh,et al.  Micromechanical modelling of matrix degradation in randomly oriented discontinuous-fibre composites , 1995 .

[6]  Larry Lessard,et al.  Multiaxial fatigue behaviour of unidirectional plies based on uniaxial fatigue experiments — I. Modelling , 1997 .

[7]  C. Demers.  Tension–tension axial fatigue of E-glass fiber-reinforced polymeric composites: fatigue life diagram , 1998 .

[8]  Stéphane Avril,et al.  Experimental identification of a nonlinear model for composites using the grid technique coupled to the virtual fields method , 2006 .

[9]  I. V. Papadopoulos,et al.  Long life fatigue under multiaxial loading , 2001 .

[10]  Cetin Morris Sonsino,et al.  Fatigue design of highly loaded short-glass-fibre reinforced polyamide parts in engine compartments , 2008 .

[11]  Kenneth Reifsnider,et al.  A cumulative damage model to predict the fatigue life of composite laminates including the effect of a fibre-matrix interphase , 1995 .

[12]  S. Mahadevan,et al.  A unified multiaxial fatigue damage model for isotropic and anisotropic materials , 2007 .

[13]  A. Plumtree,et al.  A unified fatigue failure criterion for unidirectional laminates , 2001 .

[14]  Daniel Kujawski,et al.  A unified approach to mean stress effect on fatigue threshold conditions , 1995 .

[15]  S. Mahadevan,et al.  Fatigue damage modelling of composite materials , 2002 .

[16]  H. Nayeb-Hashemi,et al.  A MULTIAXIAL FATIGUE DAMAGE MODEL FOR ORTHOTROPIC MATERIALS UNDER PROPORTIONAL LOADING , 1993 .

[17]  K. S. Kim,et al.  A fatigue life model for 5% chrome work roll steel under multiaxial loading , 2004 .

[18]  C.-H. Lee,et al.  Strength and life in thermoplastic composite laminates under static and fatigue loads. Part I: Experimental , 1998 .

[19]  Larry Lessard,et al.  Multiaxial fatigue behaviour of unidirectional plies based on uniaxial fatigue experiments—II. Experimental evaluation , 1997 .

[20]  Kenneth Reifsnider,et al.  A micromechanics model for composites under fatigue loading , 1991 .

[21]  J. Duke,et al.  DAMAGE MECHANICS AND NDE OF COMPOSITE LAMINATES , 1983 .

[22]  Bodo Fiedler,et al.  On modelling the mechanical degradation of fatigue loaded glass-fibre non-crimp fabric reinforced epoxy laminates , 2006 .

[23]  Pierre Ladevèze,et al.  Damage modelling of the elementary ply for laminated composites , 1992 .

[24]  S. L. Ogin,et al.  Damage accumulation in woven-fabric CFRP laminates under tensile loading: Part 1. Observations of damage accumulation , 1999 .

[25]  A. Alliche,et al.  Damage model for fatigue loading of concrete , 2004 .

[26]  M. Benzeggagh,et al.  Effect of interfacial decohesion on stiffness reduction in a random discontinuous-fibre composite containing matrix microcracks , 1996 .

[27]  Ara Sedrakian,et al.  Contribution of industrial composite parts to fatigue behaviour simulation , 2002 .

[28]  Moussa Karama,et al.  Damage evolution and infrared thermography in woven composite laminates under fatigue loading , 2006 .