MAT162

MAT162 serves as a material model within the LS-DYNA software, offering the capability to simulate the initiation and progression of damage in unidirectional and orthotropic fabric composite materials subjected to 3D stress fields. This model is especially useful for replicating various failure scenarios, including fiber-dominated failures, matrix damage, and it incorporates a stress-based criterion for predicting delamination failure. MAT162 excels in scenarios where the locations of delamination sites (such as interlaminar crack initiation surfaces) cannot be easily predicted.

Within MAT162, different failure modes for both the fiber and matrix phases of composite materials are accounted for. Fiber breakage is characterized using a strain-based failure criteria, involving quadratic interactions of strain components associated with fiber tension/compression, fiber shear punch, and fiber crushing damage modes, normalized with respect to their corresponding failure initiation strain amplitudes. Matrix failure, on the other hand, includes delamination and is represented by quadratic interactions of through-the-thickness strain components normalized to through-thickness tensile and shear failure strains. Additionally, the model accommodates variations in material properties with strain rate using logarithmic-based functions.

This model introduces a set of damage history variables that link the onset and progression of damage to the reduction in material stiffness. The failure criteria for fiber, delamination, and matrix damage modes serve as damage surfaces in the strain space. Damage accumulates when the strain path intersects these surfaces, and the strain increment possesses a non-zero component in the direction normal to the damage surfaces. Inside the updated damage surfaces, the model assumes a linear relationship for the strain region, with the elastic moduli diminishing according to associated accumulated damage parameters. Moreover, the composite damage model is expanded to incorporate a residual compressive strength.

Specifically for delamination, MAT162 models it in elements neighboring ply interfaces. In the event of delamination, the in-plane load-carrying capacity within the element is treated as elastic. The load-carrying behavior in the direction normal to the crack plane is influenced by the opening and closure of the crack. An opening delamination (positive through-thickness normal strain) reduces the normal to the thickness load-carrying capacity to zero. Conversely, a closing delamination (negative thickness normal strain) restores the through-thickness normal stress to its initial elastic capacity, while the through-thickness shear stresses are limited by a constant slide shear value. In cases of crack closure, this approach effectively models the friction behavior at the interface generated by the normal stress. This modeling approach allows for an efficient approximation of dynamic delamination behavior without relying on time-consuming contact surface elements.

MAT162 is available under various types of licenses, including Educational and Commercial licenses. To access MAT162, a License Agreement must be signed prior to its activation. These licenses typically include a User's Manual and Technical Support.