CT-Based Micro-Mechanical Approach to Predict Response of Closed-Cell Porous Biomaterials to Low-Velocity Impact

Abstract

Abstract:In this study, a new numerical approach based on CT-scan images and finite element (FE) method has been used to predict the mechanical behavior of closed-cell foams under impact loading. Micro-structural FE models based on CT-scan images of foam specimens (elastic-plastic material model with material constants of bulk aluminum) and macro-mechanical FE models (with crushable foam material model with material constants of foams) were constructed. Several experimental tests were also conducted to see which of the two noted (micro-or macro-) mechanical FE models can better predict the deformation and force-displacement curves of foams. Compared to the macro-structural models, the results of the micro-structural models were much closer to the corresponding experimental results. This can be explained by the fact that the micro-structural models are able to take into account the interaction of stress waves with cell walls and the complex pathways the stress waves have to go through, while the macro-structural models do not have such capabilities. Despite their high demand for computational resources, using micro-scale FE models is very beneficial when one needs to understand the failure mechanisms acting in the micro-structure of a foam in order to modify or diminish them.

Effects of Cyclic Loading and Time-Recovery on Microstructure and Mechanical Properties of Particle-Binder Composites

“…21(i) and 21(j); circle and square plots in Figs. [29][30][31][32], the prominent effects of aluminum-sucrose interactions are apparent from the first cyclic test itself, where affine motion of the sucrose crystals and aluminum particles (clearly observable in Figs. 31( Transactions of the ASME…”

“…The most commonly used techniques for imparting static and dynamic loads are (i) low strain-rate uniaxial unconfined compression and tension [8,16,17], (ii) low-frequency base excitation [18,19], (iii) Brazilian test for measuring tensile strength [20,21], (iv) high strain-rate compression and impact loading using split analysis [15,25]. The most common destructive and non-destructive techniques for observing microstructural changes are (i) speckle photography [10] and (ii) scanning electron microscopy (SEM) [11,26], which have been used to study fracture surfaces in PBX following a Brazilian test, (iii) high-speed synchrotron X-ray phase contrast imaging [27], which has been used to study in situ deformation and failure in PBX under dynamic compression [28], and (iv) micro-computed tomography (CT), which is an increasingly popular and sophisticated non-destructive imaging technique capable of characterizing the material in a three-dimensional (3D) space [29][30][31][32][33][34][35]. In the context of PBX, in situ micro-CT has been used to observe microstructural changes in material specimens during large uniaxial unconfined compression [36,37], with observations of ductile plastic flow to extensive cracking and damage mechanisms like crystal-binder delamination and transgranular fracture.…”

Application of computed tomography data–based modelling technique for polymeric low density foams, Part B: Characterization of the mechanical behaviour

“…13,14 The advantage of this modelling approach is that the obtained microstructure is similar to the real foam microstructure because features like cell size and cell shape distributions are captured in detail. [15][16][17][18] The drawbacks are the high modelling effort due to several post-processing steps and the high computational effort due to the detailed microstructure which results in a high number of elements. A further way to generate finite element models is the use of Voronoi diagrams that are a special space division technique and tessellation method, respectively.…”

Numerical Modeling and Experimental Behavior of Closed-Cell Aluminum Foam Fabricated by the Gas Blowing Method under Compressive Loading

“…Computed tomography (CT) is powerful technique for characterization of real 3D structures, capable of producing high-resolution 3D structural images with nano- and micro- level details. Geometry modeling using CT scan images has been employed in FEA [38,39,40,41] in order to study the influences of microscopic structural properties (cell anisotropy and strut geometry) on macroscopic behavior. However, optimized selection of representative images, as well as the level of detail in computer meshing, is still the topic of investigation, in order to lower the computer resources and computational time that remain rather demanding for such modeling approaches.…”