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首页> 外文期刊>Acta biomaterialia >Failure mode transition in nacre and bone-like materials.
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Failure mode transition in nacre and bone-like materials.

机译：珍珠质和骨样材料的失效模式转变。

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Mineralized biological materials such as nacre or bone achieve remarkable combinations of stiffness and toughness by way of staggered arrangements of stiff components (nanoscale or microscale fibers or tablets) bonded by softer materials. Under applied stress these components slide on one another, generating inelastic deformations and toughness on the macroscale. This mechanism is prominent in nacre, a remarkable material which is now serving as a model for biomimetic materials. In order to better identify which type of nacre should serve as a biomimetic model, the toughness of nacre from four different mollusk species was determined in this study. Nacre from the pearl oyster was found to be toughest, and for the first time remarkable deformation and fracture patterns were observed using in situ optical and atomic force microscopy. Under stress, stair-like deformation bands deformed at an angle to the loading direction, forming a dense, tree-like network. This marks a clear difference from the now well-documented "columnar" failure mode, in which deformation bands are perpendicular to the loading direction. Analytical and numerical models reveal the conditions for the transition between the columnar and stair failure modes, namely large or random overlap between inclusions and local shear stress generated by inhomogeneities in the material. "Stair" failure promotes spreading of non-linear deformation and energy dissipation, which translates into a greater toughness overall. A similar mechanism may also occur in bone, which has a microstructure which is in many ways similar to sheet nacre.
机译：珍珠母或骨头等矿化生物材料通过交错排列的硬组分（纳米级或微米级的纤维或片剂）与较软的材料粘合，从而实现了刚度和韧性的显着组合。在施加应力的情况下，这些组件会相互滑动，从而在宏观上产生非弹性变形和韧性。这种机制在珍珠母中很显着，珍珠母是一种非凡的材料，如今已成为仿生材料的模型。为了更好地确定哪种珍珠母应该用作仿生模型，本研究确定了来自四种不同软体动物物种的珍珠母的韧性。发现来自珍珠牡蛎的珍珠母最坚韧，并且首次使用原位光学和原子力显微镜观察到了显着的变形和断裂模式。在应力作用下，阶梯状变形带相对于加载方向成一定角度变形，形成了密集的树状网络。这标志着与现在有据可查的“柱状”破坏模式明显不同，在该模式中，变形带垂直于加载方向。分析和数值模型揭示了柱状和阶梯破坏模式之间过渡的条件，即夹杂物之间的大的或随机的重叠以及由材料的不均匀性产生的局部剪切应力。 “台阶”失效会促进非线性变形和能量耗散的扩散，从而转化为更高的整体韧性。类似的机制也可能发生在骨骼中，骨骼的微观结构在很多方面与珍珠层相似。

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