Abstract Carbon fiber-reinforced plastic (CFRP) composite materials have experienced increased use for load-bearing structures in automobiles owing to their high specific mechanical properties. However, critical to widespread adoption of CFRPs are the development of robust joining methods with appropriate surface preparation to maximize joint strength, as well as an improved understanding of failure mechanisms to enable computational modeling for supporting design. In the present study, an adhesively bonded non-crimp fabric CFRP single lap joint (SLJ) was investigated to quantify the effect of the composite adherend surface treatment and stacking sequence on the lap shear strength, and to assess the corresponding failure mechanisms. Single lap shear test results revealed that the highest lap shear strength was achieved by abrading the surface with sandpaper, relative to an unprepared surface or one treated by grit blasting. Similarly, an adherend with a higher effective flexural longitudinal modulus, achieved through stacking sequence, increased the lap shear strength owing to reduced Mode I loading on the adhesive joint. Distinct failure processes were observed for CFRP adherends with different stacking sequences, where the locations of intra-ply and inter-ply cracks varied as a result of variations in the in-plane and out-of-plane stresses. Notwithstanding, the final failure event for all SLJ specimens was failure of the thin layer of matrix in the 0o ply of the adherends. Three-dimensional finite element analyses of the SLJ specimens were employed to determine the local stress components driving the observed failure mechanisms within the plies of the CFRP adherends. The results of this study provide a recommended surface treatment to maximize adhesive joint strength for CFRP adherends, along with a comprehensive assessment of failure mechanisms, to inform the design and application of CFRP materials in lightweight structures.

中文翻译：

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粘合无卷曲织物碳纤维/环氧复合材料单搭接接头的性能和失效评估

摘要 碳纤维增强塑料（CFRP）复合材料由于具有较高的比机械性能，在汽车承重结构中的应用越来越广泛。然而，广泛采用 CFRP 的关键是开发稳健的连接方法，并进行适当的表面处理，以最大限度地提高连接强度，以及对失效机制的更好理解，以实现支持设计的计算建模。在本研究中，对粘合无卷曲织物 CFRP 单搭接接头 (SLJ) 进行了研究，以量化复合材料被粘物表面处理和堆叠顺序对搭接剪切强度的影响，并评估相应的失效机制。单搭接剪切试验结果表明，相对于未经处理的表面或经喷砂处理的表面，通过用砂纸打磨表面可获得最高的搭接剪切强度。类似地，通过堆叠顺序实现的具有更高有效弯曲纵向模量的被粘物，由于粘合剂接头上的模式 I 载荷减少，因此提高了搭接剪切强度。对于具有不同堆叠顺序的 CFRP 粘附体，观察到不同的破坏过程，其中层内和层间裂纹的位置因面内和面外应力的变化而变化。尽管如此，所有 SLJ 试样的最终破坏事件是被粘物 0o 层中的基质薄层破坏。SLJ 试样的三维有限元分析用于确定驱动 CFRP 粘附体层内观察到的失效机制的局部应力分量。这项研究的结果提供了一种推荐的表面处理方法，以最大限度地提高 CFRP 被粘物的粘合强度，同时对失效机制进行全面评估，为 CFRP 材料在轻质结构中的设计和应用提供信息。