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A multi-scale methodology is proposed for the study of the cellular material behavior under dynamic loading. The behavior of polymeric foams studied depends on the constitutive material and the morphology of the porous structure. The approach proposed for this study consists in developing experimental methods to impose dynamic loadings on these materials in order to measure their macroscopic response (for the identification of model parameters) and to observe and quantify the response of the foam structure. The final objective is a multi-scale modeling taking into account these physical phenomena to reproduce the macroscopic behavior. Methods and experimental techniques were developed to characterize the multi scale behavior of cellular material. Results obtained on polymeric foams at macroscopic scale constituted a database required for the identification of models implemented in the last versions of Finite-Element Software. This article presents the experimental apparatus and the results obtained at the macroscopic scale. [ABSTRACT FROM AUTHOR]

Polymeric foams are commonly used in many impact-absorbing applications and thermal-acoustic insulated devices. To improve their mechanical performances, these structures have to be modeled. Constitutive equations (for their macroscopic behavior) have to be identified and then determined by appropriate tests.Tests were carried out on polypropylene foams under high strain rate compression. In this work, the material behaviour has been determined as a function of two parameters, density and strain rate. Foams (at several densities) were tested on a uniaxial compression for initial strain rates equal to 0.34 s−1 and on a new device installed on a flywheel for higher strain rates. This apparatus was designed in order to do stopped dynamic compression tests on foam. With this testing equipment, the dynamic compressive behaviour of the polymeric foam has been identified in the strain rate range [6.7.10−4s−1, 100s−1].Furthermore, the sample compression was filmed with a high speed camera monitored by the fly wheel software. To complete this work, picture-analysis techniques were used to obtain displacement and strain fields of the sample during its compression. Comparisons between these results and stress-strain responses of polypropylene foam allow a better understanding of its behaviour. The multiscale damage mechanism, by buckling of the foam structure, was emphasised from the image analysis. [ABSTRACT FROM AUTHOR]