A Mechanical Model of Cellular Solids for Energy Absorption

Cellular materials, also known as foams, have a variety of applications in the field of packaging, and shock mitigation in the case of crash of vehicles, due to their ability to protect goods by absorbing energy in the case of impact while reducing the transmitted loads. To properly design energy absorption devices and systems such as bumpers, road barriers, helmets, sole paddings, packages, etc. it is necessary to use precisely predictive models of cellular materials, in order to select the most suitable foam for the considered application. The model must describe the stress–strain behavior, at least uniaxial compression, but also sometimes the tension and multiaxial loading, then energy absorption characteristics is evaluated. Moreover, it must take into account affecting factors like the strain‐rate. Secondarily, modeling the influence of the density heavily helps designer in selecting the best solution in terms of minimum weight per given energy to dissipate. In previous works, the authors present more than one model able to describe the quasi‐static stress–strain behavior of several cellular materials. The current paper presents a very general model able to describe, with properly identified parameters, the mechanical characteristics of a much larger variety of cellular materials including metal foams, foam mechanical properties (like, e.g., the dependence on density), and takes into account the influence of strain‐rate. Among the considered materials are the Foaminal® aluminum foam and the APM ® hybrid foam. The model is fitted to experimental tests with parameters identified based on past experimental data from the authors themselves. Tests include quasi‐static, dynamic, and impact tests at different loading speed and impact energy. It is shown that the proposed model is fundamentally suitable for most materials, virtually any foamed material, and it is an outstandingly useful tool for designers in the mentioned areas.