Non-uniform pore distribution improves impact resistance.

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The pomelo is a fruit that can withstand falls of more than 10 meters without damage, due in part to the varying pore size within its peel.

The Product Synthesis Engineering (PROSE) Lab, led by Prof. Daniel A. McAdams at Texas A&M University, has developed a mathematical model based on the non-uniform porosity of the pomelo peel. The model simulated a bioninspired aluminum foam with 66% percent of its pores dispersed within 0.6 cm of the top and bottom faces of the foam.

To test its effectiveness, the team simulated dropping the foam on its top face from a height of 1.5 meters, and then measured the stress distribution. The shock from the impact was mostly absorbed by the top face and did not fully propagate through to the bottom face, demonstrating impact resistance properties similar to that of the pomelo. This foam design could be useful in applications involving high impact, shock, or vibrations.

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The structure of pomelo peel arouses research interest in recent years because of the outstanding damping and energy dissipating performance of the pomelo peel. Researchers found that pomelo peel has varying pore size through the peel thickness; the pore size gradient is one of key reasons leading to superior energy dissipation performance of pomelo peel. In this paper, we introduce a method to model pomelo peel bioinspired foams with non-uniform pore distribution. We generate the skeletal open cell structure of the bioinspired foams using Voronoi tessellation. The skeleton of the bioinspired foams is built as three-dimension beam elements in a full-scale finite element model. The quasi-static and dynamic mechanical behaviors of the pomelo peel bioinspired foams could be derived through a finite element analysis. We illustrate our method using a case study of pomelo peel bioinspired aluminum foams under quasi-static compression and free fall impact circumstances. The case study results validate our method and demonstrate the superior impact resistance and damping behavior of bioinspired foam with gradient porosity for designers.” (Ortiz et al 2018:1)

Journal article
A Model for the Design of a Pomelo Peel Bioinspired FoamJournal of Mechanical DesignJuly 20, 2018
Jonel Ortiz, Guanglu Zhang, Daniel A. McAdams

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