Gradient design of metal hollow sphere (MHS) foams with density gradients

Abstract

SMetal hollow sphere (MHS) structures with a density gradient have attracted increasing attention in the effort to pursue improved energy absorption properties. In this paper, dynamic crushing of MHS structures are discussed. MHS of different gradients are modelled by stacks of hollow spheres of the same external diameter but different wall thicknesses in the crushing direction. Then based on the dynamic performance of MHS structures with uniform density, a crude semi-empirical model is developed, showing the effect of density gradient in energy absorption and protection against dynamic crush. The model provides some guidance in the design of MHS structures. Following this, dynamic responses of density graded MHS foams are analyzed using explicit finite element simulation and the proposed formula. Results show that the simple semi-empirical model can predict the response of density gradient MHS foams, thus be used for the gradient design of MHS structures.

Numerical Investigation on Dynamic Crushing Behavior of Auxetic Honeycombs with Various Cell-Wall Angles

“…The full densification can be determined by the last main local maxima point, with the corresponding strain as the densification strain [34].…”

Compressive behavior of tailor-made metallic foams (TMFs): Numerical simulation and statistical modeling

“…Thus, the layers of the structure are crushed progressively (layer by layer) [7,27]. On the other hand, it has to be mentioned that the distribution of the cells (horizontal and vertical distance of the cells) has a great impact on the mechanical properties of TMFs [17].…”

“…Many researchers have focused on the different combinations of reinforcement and matrix while some others are dealing with the effects of hollow sphere size and distribution on the mechanical properties and energy absorption capability [3,6]. It has been reported that energy absorbing properties of MMSFs can be customized by the appropriate selection of matrix and heat treatment procedure as well as the reinforcement composition, wall thickness, diameter and volume fraction [7][8][9][10].…”

An analytical model of a clamped sandwich beam under low-impulse mass impact

“…The foam core provides not only the transverse pressure, but also the bending/shear strength during the coupled deformation between the core compression and the beam bending/stretching phases. Moreover, researches show that the responses of the foam at the impact or distal ends are different for different impacting conditions (Liu and Zhang, 2009;Liu, et al, 2012), which indicates that the pressures loads on the back and front faces due to the transverse compression of the core may be different, and asynchronous. As a result, how to consider the bending/shear effect of the foam core during the deformation, and describe the transverse pressures on the face sheets caused by the core compression, are the key points in the analytical modeling of sandwich beams, and have not been absolutely solved to per author's knowledge.…”