A Comprehensive Model for Determining Tensile Strengths of Various Unidirectional Composites

Abstract

Simultaneous fiber-failure (SFF) model that determines tensile strengths for various systems of unidirectional composites comprehensively is presented. The SFF derives the strength of unidirectional composites as a function of the single-fiber strength distribution, interfacial shear strength, and matrix strength. The point of the SFF is that a fiber group which is considered to be experiencing simultaneous fiber failures triggered by neighboring fiber failures is assumed to fail when the weakest fiber in the fiber group fails. We discuss a method to determine the magnitude of the fiber group for various systems of composites on a basis of whether a crack located near a bi-materials interface penetrates into another material or deflects along the interface. The SFF is established by integrating the magnitude of the simultaneous fiber failures into the conventional Global load sharing model.

Mechanical characterization and modeling of poly (β‐hydroxybutyrate)‐co‐poly(β‐hydroxyvalerate)–Alfa fiber‐reinforced composites

“…GLS is a statistical method that accounts for progressive fiber failure and subsequent fiber load redistribution by shear lag through the composite matrix . In the GLS model, the strength of a composite loaded in the fiber direction is controlled by the strength of the reinforcing fibers, which are statistically characterized by the Weibull distribution . Weibull parameters σ 0 , L 0 , and m , and the fiber‐matrix interfacial shear strength, τ, and the average fiber diameter, D , are used to estimate the composite strength as follows: Where σ c is considered the critical fiber stress and is given by: …”

“…The GLS model, which is known to overestimate the strength of many composites that exhibit damage localization, was modified to account for simultaneous fiber failure (SFF) initiated by a weak fiber within a group . The SFF model uses the interaction between the strengths of the fiber, matrix, and fiber–matrix interface to quantify a number of SFFs within an arbitrary region of the composite.…”

Temperature dependence of glass fiber/epoxy interface normal strength examined by a cruciform specimen method

“…It has been reported that if the interface strength exceeds a specific value, the mechanical properties of composite material may deteriorate [1]. However, it is difficult to evaluate the interface strength conventionally [2,3].…”

A Numerical Simulation of Time-Dependent Interface Failure Under Shear and Compressive Loads in Single-Fiber Composites

“…The degradation of the interfacial stress transfer capacity causes the propagation of interfacial failure, and consequently, an increase in the stress recovery length around the fiber failure. This increase can be associated with a decrease in the strength of unidirectional composites [8][9][10][11][12]. Hence, the evolution of time-dependent interfacial failure can play a key role in ensuring the long-term durability of composite materials.…”

“…In a previous study [9], we integrated the frictional effect into the interfacial failure progression. In these articles [9][10][11][12][13][14][15][16], a time-dependent interfacial failure criterion plays a key role in precisely predicting the progression of interfacial failure. Several studies have shown that interfacial shear strength decreases with time [9,[14][15][16].…”