Reliability Approach to the Tensile Strength of Unidirectional CFRP Composites by Monte-Carlo Simulation

A numerical technique based on the Monte-Carlo method in a shear-lag model is developed to simulate the tensile strength and fracture process for a unidirectional carbon-fiber-reinforced-plastic (CFRP) composite. The technique improves on the conventional approach by using an rmin method that can determine the stresses working on the fiber and matrix elements as the damage progresses. The rmin method is based on tracking the incremental ratio of the strength of an element to its stress. The present model includes the effect of the sliding frictional forces around fiber breaks caused by debonding between the fiber and matrix. Statistical properties of the tensile strength were obtained through simulation runs involving 100 samples for each value of the frictional force parameter. Also studied was the size effect in composite strength with increasing numbers of fibers, N, where it was found numerically that mean strength varies linearly as 1[ln(N)]12 and coefficient of variation varies linearly as 1ln(N), as suggested from a simple theory.

[1]  L. N. McCartney,et al.  Statistical Theory of the Strength of Fiber Bundles , 1983 .

[2]  S. Phoenix,et al.  Interfacial Shear Strength Studies Using the Single-Filament-Composite Test. I: Experiments on Graphite Fibers in Epoxy , 1989 .

[3]  C. Zweben,et al.  Tensile failure of fiber composites. , 1968 .

[4]  R. L. Smith,et al.  A comparison of probabilistic techniques for the strength of fibrous materials under local load-sharing among fibers☆ , 1983 .

[5]  S. L. Phoenix,et al.  Probability distributions for the strength of composite materials II: A convergent sequence of tight bounds , 1981 .

[6]  B. D. Agarwal,et al.  Analysis and Performance of Fiber Composites , 1980 .

[7]  M. Piggott,et al.  The glass fibre-polymer interface: III—Pressure and coefficient of friction , 1985 .

[8]  S. L. Phoenix,et al.  Approximations for the strength distribution and size effect in an idealized lattice model of material breakdown , 1991 .

[9]  S. Batdorf,et al.  Tensile Strength of Unidirectionally Reinforced Composites — I , 1982 .

[10]  S. Tsai,et al.  Introduction to composite materials , 1980 .

[11]  B. W. Rosen,et al.  Tensile failure of fibrous composites. , 1964 .

[12]  K. Goda,et al.  Considerations of the reliability of tensile strength at elevated temperature of unidirectional metal matrix composites , 1989 .

[13]  M. Piggott,et al.  The glass fibre—polymer interface: I—theoretical consideration for single fibre pull-out tests , 1985 .

[14]  Tsu-Wei Chou,et al.  Microstructural design of fiber composites , 1992 .

[15]  K. P. Oh.  A Monte Carlo Study of the Strength of Unidirectional Fiber-Reinforced Composites , 1979 .

[16]  T. Ozaki,et al.  Simulation on tensile failure process of unidirectional hybrid FRP. , 1985 .

[17]  E. Reedy.  Fiber Stresses in a Cracked Monolayer: Comparison of Shear-Lag and 3-D Finite Element Predictions* , 1984 .