Institute of Zoology, Functional Morphology and Biomechanics, Kiel University, Kiel, Germany.
Faculty of Mechanical Engineering, University of Guilan, Rasht, Iran.
J R Soc Interface. 2020 Jul;17(168):20200378. doi: 10.1098/rsif.2020.0378. Epub 2020 Jul 15.
The exoskeleton of nearly all insects consists of a flexible core and a stiff shell. The transition between these two is often characterized by a gradual change in the stiffness. However, the functional significance of this stiffness gradient is unknown. Here by combining finite-element analysis and multi-objective optimization, we simulated the mechanical response of about 3000 unique gradients of the elastic modulus to normal contacts. We showed that materials with exponential gradients of the elastic modulus could achieve an optimal balance between the load-bearing capacity and resilience. This is very similar to the elastic modulus gradient observed in insect cuticle and, therefore, suggests cuticle adaptations to applied mechanical stresses; this is likely to facilitate the function of insect cuticle as a protective barrier. Our results further indicate that the relative thickness of compositionally different regions in insect cuticle is similar to the optimal estimation. We expect our findings to inform the design of engineered materials with improved mechanical performance.
几乎所有昆虫的外骨骼都由一个柔韧的核心和一个坚硬的外壳组成。这两者之间的过渡通常以刚度的逐渐变化为特征。然而，这种刚度梯度的功能意义尚不清楚。在这里，我们通过结合有限元分析和多目标优化，模拟了大约 3000 种独特的弹性模量梯度对正常接触的力学响应。我们表明，具有指数弹性模量梯度的材料可以在承载能力和弹性之间达到最佳平衡。这与在昆虫外骨骼中观察到的弹性模量梯度非常相似，因此表明外骨骼适应于施加的机械应力；这可能有助于昆虫外骨骼作为保护屏障的功能。我们的结果还表明，昆虫外骨骼中化学成分不同的区域的相对厚度与最佳估计值相似。我们希望我们的发现能为设计具有改进机械性能的工程材料提供信息。
