Non‐destructive fatigue damage characterization of laminated thermosetting fibrous composites

The fatigue behaviour of the laminated thermosetting Fiberdux 6376-HTA composite material is studied experimentally for both constant and variable amplitude stress reversal loading. The fatigue-induced material degradation is correlated to non-destructive evaluation data obtained from C-scan graphs through the concept of the damage severity factor (DSF ). The DSF is able to account for the varying severity of damage at the different specimen locations and is used to quantify the fatigue-induced damage. The concept of the DSF, introduced earlier by the authors for constant amplitude fatigue loading of thermoplastic fibrous composites, is applied to characterize fatigue damage of thermosetting fibrous composites and is extended to account for variable amplitude loading. Constant amplitude fatigue tests at various stress levels were performed to correlate fatigue damage to the change of mechanical properties, such as axial stiffness, residual tensile strength and interlaminar shear strength, and to develop expressions to relate DSF to the degradation of the mechanical properties with increasing fatigue damage. Correlation between DSF evolution and consumed fatigue life is made and fatigue damage functions involving stress amplitude dependency are formulated. These expressions together with a modified rainflow method are then used to assess fatigue life under variable amplitude fatigue loading; computed fatigue lives are compared against experimental results.

[1]  David H. Allen,et al.  A thermomechanical constitutive theory for elastic composites with distributed damage. II: Application to matrix cracking in laminated composites , 1987 .

[2]  Peter W. R. Beaumont,et al.  Matrix cracking and stiffness reduction during the fatigue of a (0/90)s GFRP laminate , 1985 .

[3]  Larry Lessard,et al.  Effects of Material Nonlinearity on the Three-Dimensional Stress State of Pin-Loaded Composite Laminates , 1996 .

[4]  Guk-Rwang Won.  American Society for Testing and Materials , 1987 .

[5]  Anoush Poursartip,et al.  The fatigue damage mechanics of a carbon fibre composite laminate: II—life prediction , 1986 .

[6]  Tomas Ireman,et al.  Three-dimensional stress analysis of bolted single-lap composite joints , 1998 .

[7]  Sp.G. Pantelakis,et al.  Fatigue damage of APC-2 composite assessed from material degradation and non-destructive evaluation data , 1999 .

[8]  Kenneth Reifsnider,et al.  Stiffness-reduction mechanisms in composite laminates , 1982 .

[9]  Asd Wang,et al.  A Stochastic Model for the Growth of Matrix Cracks in Composite Laminates , 1984 .

[10]  R. Talreja.  Chapter 3 - Damage Characterization , 1991 .

[11]  Charles E. Harris,et al.  Internal State Variable Approach for Predicting Stiffness Reductions in Fibrous Laminated Composites with Matrix Cracks , 1989 .

[12]  A. Rotem,et al.  Fatigue and residual strength of composite laminates , 1986 .

[13]  Siu-Tong Choi,et al.  A Study of Fatigue Damage and Fatigue Life of Composite Laminates , 1996 .

[14]  Tk O'Brien,et al.  Towards a Damage Tolerance Philosophy for Composite Materials and Structures , 1990 .

[15]  Kenneth Reifsnider,et al.  Long-Term Fatigue Behavior of Composite Materials , 1983 .

[16]  David H. Allen,et al.  A thermomechanical constitutive theory for elastic composites with distributed damage—I. Theoretical development , 1987 .

[17]  R. J. Nuismer,et al.  A Theory for Progressive Matrix Cracking in Composite Laminates , 1989 .

[18]  Charles E. Harris,et al.  Experimental Verification of a Progressive Damage Model for IM7/5260 Laminates Subjected to Tension-Tension Fatigue , 1995 .