While the surface asperities of mineral platelets are widely believed to play important roles in stiffening, strengthening, and toughening nacre, their effects have not been thoroughly investigated. Here, a computationally efficient bar-spring model is adopted to simulate, as platelets with multiple interfacial asperities slide over each other, the tensile force versus elongation behaviors as well as the effective mechanical properties such as modulus, strength, and work-to-fracture in nacre or nacre-like composites. The model employs an effective cohesive law derived from a micromechanical model based on the kinematic and deformation analysis of a single pair of contacting asperities to characterize the traction-separation relationship during the asperity inter-climbing. Strikingly, we find that the mineral asperities and resulting interfacial roughness can elevate the composites’ strength and toughness by up to 2–3 orders of magnitude through a combination of mechanical interlocking and multimodal friction-like mechanisms. Of particular interest is that the asperity-induced strengthening and toughening mechanisms are insensitive to the asperity shapes such as ellipse, hyperbolic cosine, cosine, and parabola. These findings may provide useful guidelines for developing advanced engineering composites with nacre-inspired interface designs.

中文翻译：

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矿物粗糙度通过互锁和摩擦式滑动强化珍珠层


虽然人们普遍认为矿物片晶的表面粗糙度在珍珠质的硬化、强化和增韧方面发挥着重要作用，但它们的影响尚未得到彻底研究。这里，采用计算效率高的棒弹簧模型来模拟当具有多个界面粗糙度的薄片彼此滑动时，拉伸力与伸长率的关系以及有效的机械性能，例如模量、强度和断裂功在珍珠质或类珍珠质复合材料中。该模型采用基于单对接触粗糙体的运动学和变形分析的微机械模型导出的有效内聚定律来表征粗糙体相互爬升期间的牵引-分离关系。引人注目的是，我们发现，通过机械联锁和多模态摩擦机制的结合，矿物粗糙度和由此产生的界面粗糙度可以将复合材料的强度和韧性提高多达 2-3 个数量级。特别令人感兴趣的是，粗糙体引起的强化和增韧机制对粗糙体形状（例如椭圆、双曲余弦、余弦和抛物线）不敏感。这些发现可能为开发具有珍珠层启发的界面设计的先进工程复合材料提供有用的指导。