Selecting Material Models for the Simulation of Foams in LS-DYNA

Foams are multi-phase materials that exhibit dramatically different properties that depend on the matrix material as well as the pore microstructure. This additional degree of freedom from the presence of the gas phase makes material modelling for foams a difficult matter. LS-DYNA offers a variety of material models, each with capabilities designed to capture the unique behaviour of a different types of foam. The selection of the correct material model depends to a large extent, on the observed behaviour of the foam during the test. Other factors will include the actual situation under simulation, which becomes important for highly non-linear materials, where a single material model often cannot capture all the dependencies, forcing a localized material calibration. The material calibration itself is not easy because of the lack of set procedures for characterization. Previous research has devoted a lot of effort to enhancing these material models to improve their capabilities as well as to make them easier to use. In our current work, we seek to lay down a framework to help us understand the different behavioural classes of foams. Following a methodology that we previously applied to plastics, we will then attempt to propose the right LS-DYNA material models that best capture these behaviours. Guidelines for model selection will be presented as well as best practices for characterization. Limitations of existing material models will be discussed.