Morano Chiara, Terasaki Nao, Gao Tianyi, Lubineau Gilles, Alfano Marco
Department of Mechanical, Energy and Management Engineering, University of Calabria, Rende (CS) 87036, Italy.
National Institute of Advanced Industrial Science and Technology (AIST), Sensing System Research Center (SSRC), 807-1 Shuku-machi, Tosu 841-0052, Saga, Japan.
ACS Appl Mater Interfaces. 2023 Aug 30;15(34):40887-40897. doi: 10.1021/acsami.3c06656. Epub 2023 Aug 10.
We investigate the mechanics of crack propagation in architected adhesive joints whose adherends are inspired to the base plate of the barnacle () , and feature an array of buried hollow cylindrical channels located perpendicularly to the direction of crack growth. Selective laser sintering is used to obtain the adherends that are subsequently bonded in the double cantilever beam configuration to ascertain the mechanics of crack growth. Finite element (FE) simulations are deployed to determine the strain energy release rate (ERR) and to elucidate the salient features of the fracture process. It is shown that the channels induce a modulation of the ERR and enable a crack tip shielding mechanism. Besides, FE simulations based on a cohesive zone approach indicate the occurrence of crack pinning/depinning cycles that are validated via experiments. A highlight of the present study is the use of a mechanoluminescent (ML) coating to unravel the evolution of the transient stress field in the crack tip region. The coating comprises an optical epoxy resin loaded with doped strontium aluminate phosphors (SrAlO/Eu) and converts mechanical energy into light emission with intensity proportional to the magnitude of mechanical stress. By combining the ML emission patterns with the stress distribution obtained from FEA, we unveil interesting details of snap-through cracking in architected bio-inspired adhesive joints.
我们研究了仿生粘合接头中裂纹扩展的力学机制，其被粘物的灵感来源于藤壶的基板（ ），并具有一系列垂直于裂纹扩展方向的埋入式空心圆柱通道。采用选择性激光烧结获得被粘物，随后将其以双悬臂梁结构进行粘结，以确定裂纹扩展的力学机制。利用有限元（FE）模拟来确定应变能释放率（ERR），并阐明断裂过程的显著特征。结果表明，这些通道会引起ERR的调制，并实现裂纹尖端屏蔽机制。此外，基于内聚区方法的有限元模拟表明存在裂纹钉扎/脱钉循环，这已通过实验得到验证。本研究的一个亮点是使用机械发光（ML）涂层来揭示裂纹尖端区域瞬态应力场的演变。该涂层由负载有掺杂铝酸锶磷光体（SrAlO/Eu）的光学环氧树脂组成，能将机械能转化为与机械应力大小成正比的发光强度。通过将ML发射模式与从有限元分析获得的应力分布相结合，我们揭示了仿生生物启发式粘合接头中突跳开裂的有趣细节。
