Numerical Prediction of Failure in Unidirectional Fiber Reinforced Composite

Fiber-reinforced polymer composites exhibit orthotropic mechanical properties and particularly low strength in the out-of-plane direction. The use of classical failure criteria that consider transverse isotropy to evaluate these composite materials implies an overestimation of their out-of-plane strength, which could lead to a nonconservative and even catastrophic design. The Molker failure criteria developed for orthotropic materials consider the LaRC05 failure modes as a basis, with two additional failure modes for the out-of-plane direction of noncrimp fiber (NCF)-reinforced composites. Given the similarity in configuration and orthotropic behavior of unidirectional fiber fabric reinforced composites to NCF-reinforced composites, Molker failure criteria are implemented and applied in this research to determine the initiation of out-of-plane failure in unidirectional fiberglass fabric composites. The criteria are programmed in the form of a module coupled to a constitutive model available in a finite element method (FEM) package. Then, the mechanical properties and failure parameters of the unidirectional fiber-reinforced composite are determined. Model validation is accomplished by comparing numerical and experimental results of out-of-plane failure in a corrugated panel. In addition, several failure criteria used in unidirectional fiber-reinforced composite that consider transverse isotropy are evaluated. The results of critical load at the onset of transverse out-of-plane failure obtained by using the Molkerorthotropic criterion prove to be superior in accuracy compared to those obtained with the criteria commonly applied to this type of materials.

Automated summary

This study implements and applies the Molker failure criteria to determine the initiation of out-of-plane failure in unidirectional fiberglass fabric composites. The results show that the Molker orthotropic criterion is superior in accuracy compared to commonly applied criteria for this type of materials.