Quantifying Localized Stresses in the Matrix of a Fiber‐Reinforced Composite via Mechanophores
Quantifying Localized Stresses in the Matrix of a Fiber‐Reinforced Composite via Mechanophores
复制标题
通过力力团量化纤维增强复合材料基体中的局部应力
DOI：
10.1002/macp.202300298
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发表时间：
2023
影响因子：
2.5
通讯作者：
Davis, Chelsea S.
中科院分区：
文献类型：
--
作者：
Haque, Nazmul;Gohl, Jared;Chang, Chia‐Chih;Chang, Hao Chun;Davis, Chelsea S.
了解纤维增强聚合物（FRP）内部的应力分布对于延长其使用寿命至关重要。机械响应分子力探针的整合，称为mechanophores，提出了一个潜在的解决方案，使直接监测应力集中。在这项研究中，螺吡喃（SP）机械载体（MP）嵌入聚二甲基硅氧烷（PDMS）基质中，以可视化在单纤维增强框架内加载期间的应力局部化。SP机械基团通过响应于机械力的异构化经历从非荧光状态到活性状态（mercury）的转变。使用轴向安装在基体内的单根纤维，复制了传统纤维增强复合材料中观察到的基本失效模式。样品在单轴拉伸载荷下沿纤维方向沿着应变，并通过MP活化观察应力的局部化。应力集中在靠近纤维区域的基体中，该区域远离纤维表面逐渐减小。共聚焦显微镜用于可视化机械基团活化并定量评估荧光强度。有限元建模用于开发校准，以基于观察到的荧光强度来量化应力。这些结果强调了采用这些机械响应分子作为可视化真实的时间应力分布的潜在手段的可行性，从而促进了高性能复合材料的设计。
Understanding the stress distribution within fiber‐reinforced polymers (FRPs) is critical to extending their operational lifespan. The integration of mechanoresponsive molecular force probes, referred to as mechanophores, presents a potential solution by enabling direct monitoring of stress concentrations. In this study, spiropyran (SP) mechanophores (MPs) are embedded within a polydimethylsiloxane (PDMS) matrix to visualize stress localization during loading within a single fiber‐reinforced framework. The SP mechanophore undergoes a transition from a non‐fluorescent state to an active state (merocyanine) through isomerization in response to mechanical forces. Using a single fiber mounted axially within the matrix, the fundamental failure modes observed in conventional fiber‐reinforced composites are replicated. Samples are strained under uniaxial tensile loading along the fiber direction and the localization of stresses is observed via MP activation. Stresses are concentrated in the matrix near the fiber region that gradually decreases away from the fiber surface. Confocal microscopy is used to visualize mechanophore activation and quantitatively assess fluorescence intensity. Finite element modeling is used to develop a calibration to quantify the stresses based on the observed fluorescence intensity. These outcomes underscore the viability of employing these mechanoresponsive molecules as a potential means to visualize real‐time stress distribution, thereby facilitating the design of high‐performance composites.