Research Projects

Metallic open-cell foam are a new class of materials having a combination of properties such as lightweight, energy absorption, heat dissipation, acoustic shielding, and electromagnetic shielding. Because of their properties, these foams find applications in the automotive industry, construction, aerospace, defense, etc. [1]. In aerospace applications, open-cell foams are used in sandwich panels as a protective layers for spacecraft and satellites against impact from space debris [2]. Open-cell foam consists of connecting cell edges or struts, which form open space between them. For the structural design of spacecraft and satellites, a suitable constitutive model is required, which should be able to predict the deformation and failure behavior for the open-cell foam under wide range of loading conditions. There have been efforts to understand the deformation and failure of open-cell foam. In most of these studies, meso-scale structure, where individual cell struts are considered, have been used to derive the stress-strain relation [3, 4]. Due to high computational cost, it is almost impossible to use these models for the design of large structures. Homogenized constitutive models are proposed for the open cell-foam, however, they are limited to the small deformation [5, 6]. Hence, there is a need to develop a homogenized constitutive model accounting for the microscale constitutive behavior of the material and the meso-scale structural topology of the open-cell foams which can accurately predict the large deformation elasto-plastic response and failure of open-cell metallic foams in the wide range of loading condition. Thus, the objective of the current proposal is to develop, validate, and apply a rate-dependent homogenized constitutive model for analyzing the deformation and failure of open-cell foam material. To avoid the complexity of mathematical description in the phenomenological model and high computational cost in computational homogenization, a hybrid approach combining the classical plasticity framework with the neural network-based approach will be used [5]. The developed constitutive model will be validated with the uni-axial compression test data at different strain rates 0.001 s^-1 to 1000 s^-1 . Test specimens of the open-cell metallic foams will be manufactured using the Laser Powder Bed Fusion (LPBF) additive manufacturing process. With additive manufacturing, it is possible to manufacture the foams with a controlled microstructure, which will help us analyze the effects of mesostructure on the deformation of foams. The compression test at low strain rates (0.001 s^-1 to 1 s^-1 ) will be performed in a universal test machine, whereas high strain rate (upto 1000 s−1 ) will be carried out in split-Hopkinson pressure bar (SHPB) setup. Digital image correlation and high-speed imaging will be used for measurement and observation of deformation. Once the model is validated for the uniaxial compression test, it will be applied to a case of bullet impact on a sheet of open-cell foam. Experiments for the bullet impact will be performed, and simulations based on the developed constitutive model will be compared with experimental results. References [1] Wan, T., Liu, Y., Zhou, C., Chen, X., and Li, Y., Journal of Materials Science & Technology, 62:11–24, 2021. [2] Ryan, S. and Christiansen, E., NASA Johnson Space Center, 2015. [3] Tang, Q., He, Q., and Chen, X., Thin-Walled Structures, 195:111440, 2024. [4] Thiyagasundaram, P., Wang, J., Sankar, B. V., and Arakere, N. K., Engineering Fracture Mechanics, 78(6):1277–1288, 2011. [5] Settgast, C., Hütter, G., Kuna, M., and Abendroth, M. A, International Journal of Plasticity, 126: 102624, 2020. [6] Abendroth, M., Malik, A., and Kiefer, B., International Journal of Mechanical Sciences, 270:109094, 2024.