A robust optical strain sensor, called fiber Bragg grating, is employed to measure the effective cure shrinkage—a part of cure shrinkage that is accumulated only after the gel point—of a dual cure adhesive during each stage of curing—(1) UV-curing stage and (2) thermal-curing stage. Unique experimental setups and procedures are developed and implemented to cope with the technical challenges associated with each stage of curing, including gel point detection and uniform curing. The effective cure shrinkage is measured to be 2.1% and 0.78% for acrylate compound (UV-curing) and two epoxy compounds (thermal-curing), respectively. The measurement accuracy of the proposed approach is corroborated by an additional measurement under the identical curing conditions. The results can be used to predict the cure-induced residual stresses of dual curable adhesives.

中文翻译：

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用光纤布拉格光栅传感器测量双固化胶粘剂的体积有效固化收缩率

坚固的光学应变传感器，称为光纤布拉格光栅，用于测量双固化粘合剂在每个固化阶段的有效固化收缩率——固化收缩率的一部分，仅在胶凝点之后累积——(1) UV-固化阶段和（2）热固化阶段。开发并实施了独特的实验设置和程序，以应对与固化每个阶段相关的技术挑战，包括凝胶点检测和均匀固化。经测量，丙烯酸酯化合物（UV 固化）和两种环氧化合物（热固化）的有效固化收缩率分别为 2.1% 和 0.78%。所提出方法的测量精度通过在相同固化条件下的额外测量得到证实。