Design and Analysis of Composite Structures for Automotive Applications

2Phenomenological Failure Criteria of Composites

2.1 Phenomenological Failure Criteria

2.1.1 Criteria for Static Failure Behavior

In fiber‐reinforced composites, both the failure behavior, which is either ductile or brittle, as well as the type of failure (fiber or matrix fracture), are strongly dependent on the components of the applied stress, type and compositions of components, the fiber arrangement and manufacturing procedures. For design purposes, most attention is paid to the geometric details of an internal structure composite. The other composition and manufacturing factors must be fixed.

Among others, the highest loading capacity for a uniaxial stress state provides unidirectional fiber‐reinforced composites (Sun 2000). Unidirectional fiber‐reinforced materials are best suited to chassis and drivetrain applications because the stresses in such systems can be extraordinarily high. Some failure modes of a unidirectional single layer with extensive photographs of crack surfaces in experiments are exposed in Agarwal et al. (2006). The majority of problems studied in this book focus on this type of composite.

2.1.2 Stress Failure Criteria for Isotropic Homogenous Materials

In the case of metallic materials, static strength verification is often based on the ratio of a comparative stress (e.g. von Mises stress) to a strength value obtained from a uniaxial tensile test.

The main normal stress hypothesis has established itself in the evaluation of brittle materials under ...