Crush behavior optimization of multi-tubes filled by functionally graded foam

• This paper introduces layered FGF filled tubes models and predicts their crush behavior.
• The FE results of FGF validated with experimental results of uniform density foam.
• Polynomial and sinusoidal functions is used to control the density gradient of FGF layers.
• Specified energy absorption and peak force are selected as design parameters for optimization of FGF layers.

Crush behavior of different arrangements of multi-tubes filled by functionally graded foams (FGF) are evaluated in this study. Our study shows that the energy absorption of FGF filled multi-tubes is higher than their equivalent multi-tubes filled by uniform foams. Also, the results show that the type of function employed for grading foam has significant effect on their crush response. In this study, multi-objective optimization was carried out using geometrical average and multi-design objective (MDO) methods. The results give new design ideas under axial loading to improve energy absorption performance of FGF foam-filled tubes.

This paper introduces a model for single and multi-tubes filled by functionally graded foam (FGF) and predicts their crush behavior under quasi static loading conditions (Fig. 1). The material used for the tube wall was deep-drawn thin-walled Al tubes (99.7% Al) with 25 mm diameter and 0.29 mm wall thickness. The sinusoidal and polynomial functions have been used to control the density gradient of FGF layers, in the length of the filled tubes (Fig. 2), as:equation(1)ρf(y)=m1sin(p1y)+n1,0≤y≤lequation(2)pf(y)=pmin+(pmax−pmin)[yL]m,0≤y≤LOur study shows that the energy absorption of FGF filled multi-tubes is higher than the uniform foams. Also, the results show that the type of function employed for grading of foam has significant effect on their crush response.Figure optionsDownload as PowerPoint slide