| Description |
Open-cell metallic foams show excellent potential for application in lightweight loadbearing structures, electrodes in energy-storage devices, biomedical implants, and heat exchangers, to name a few. In order to accelerate their deployment in engineering applications, it is important to establish direct links among the manufacturing processes, the resulting 3D microstructure, and the mechanical performance of open-cell foams. This work presents a novel approach that combines X-ray computed tomography (CT) imaging, in situ mechanical testing, and high-fidelity finite element (FE) simulations aimed at characterizing, and ultimately predicting, the mechanical behavior of a broad range of open-cell aluminum foams. Two mechanical experiments are developed to characterize both local and global behavior of aluminum foams. These experiments combine X-ray CT imaging and in situ mechanical testing to observe, in near real time, the deformation and failure of foams during tensile and compressive loading. The first experiment, performed at the microscale, measures tensile behavior of individual ligaments extracted from bulk foams. The data from this experiment are used to quantify elastic-plastic behavior of aluminum fabricated via investment casting. The second experiment is used to characterize the macroscopic response of aluminum foams subjected to compressive loading. In addition to measuring compressive strength of bulk foams, this test allows for observation of local mechanisms (e.g., ligament buckling, flexure, fracture) that give open-cell foams excellent energyabsorption properties during crushing. The mechanical and image data obtained from the aforementioned experiments enable development of high-fidelity FE models of open-cell foams. The ligament tensile data are used to calibrate plasticity parameters needed to predict accurately the yielding, hardening, and ultimate rupture of individual ligaments. The bulk compression data are used to fine-tune element deletion, contact, and friction parameters, which are necessary to predict crush strength and densification of virtual instantiations of aluminum foams. The resulting set of model parameters will enable development of a virtual testing framework, which will ultimately allow for accelerated design of new open-cell foam configurations. |
