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Bioinspir Biomim. 2018 Dec 19;14(1):016018. doi: 10.1088/1748-3190/aaf531.
The calcitic spines of the sea urchins Heterocentrotus mamillatus and H. trigonarius are promising role models for lightweight applications, bone tissue scaffolds and energy dissipating processes due to their highly porous and organized structure. Therefore, mechanical properties including Young's Modulus, strength, failure behaviour and energy dissipation efficiency have been investigated in depth with uniaxial compression experiments, 3-point bending tests and resonance frequency damping analysis. It was found that despite a very similar structure, H. trigonarius has a significantly lower porosity than H. mamillatus leading to a higher strength and Young's Moduli, but limited ability to dissipate energy. In order to show reliable energy dissipation during failure in uniaxial compression, a transition porosity of 0.55-0.6 needs to be exceeded. The most effective structure for this purpose is a homogeneous, foam-like structure confined by a thin and dense shell that increases initial strength and was found in numerous spines of H. mamillatus. Sharp porosity changes induced by dense growth layers or prominent wedges of the spines' radiating building principle act as structural weaknesses, along which large flakes can be spalled, reducing the energy dissipation efficiency considerably. The high strength and Young's Modulus at the biologically necessary high porosity levels of the spines is useful for Heterocentrotus and their construction therefore remains to be a good example of biomimetics. However, the energy dissipative failure behaviour may be regarded as a mere side effect of the structure.
棘皮动物海胆的方解石棘刺因其高度多孔且组织有序的结构，是轻型应用、骨组织支架和能量耗散过程的理想模型，在这些方面具有很大的应用潜力。因此，人们通过单轴压缩实验、三点弯曲测试和共振频率阻尼分析等方法，深入研究了包括杨氏模量、强度、失效行为和能量耗散效率在内的力学性能。研究发现，尽管结构非常相似，但 H. trigonarius 的孔隙率明显低于 H. mamillatus，导致其强度和杨氏模量更高，但能量耗散能力有限。为了在单轴压缩失效时表现出可靠的能量耗散，需要超过 0.55-0.6 的过渡孔隙率。为此，最有效的结构是由薄而密的外壳限制的均匀泡沫状结构，这种结构可以提高初始强度，在 H. mamillatus 的许多棘刺中都可以发现这种结构。由于棘刺的辐射状建筑原理的密集生长层或突出的楔形导致的孔隙率急剧变化，会形成结构弱点，大的薄片可能会剥落，从而大大降低能量耗散效率。棘刺在生物必需的高孔隙率水平下具有高强度和杨氏模量，这对 Heterocentrotus 很有用，因此它们的结构仍然是仿生学的一个很好的例子。然而，能量耗散失效行为可能被视为结构的一个附带现象。
