In this paper, a procedure to obtain fully uncoupled multi-directional stacking sequences for delamination specimens is outlined. For such sequences, in-plane, membrane-bending and torsion–bending coupling terms are null (in closed-form solution in the framework of classical laminated plate theory) for the entire stack and for both its halves, which form two arms in the pre-cracked region of a typical delamination specimen. This is achieved exploiting the superposition of quasi-trivial quasi-homogeneous stacking sequences, according to appropriate rules. Any pair of orientations of the plies embedding the delamination plane can be obtained. To assess the effectiveness of the proposed approach, a fully uncoupled multi-directional sequence is designed and compared to other relevant sequences proposed in the literature. Finite element simulations of double cantilever beam test are performed using classic virtual crack closure technique and a revised state-of-the-art virtual crack closure technique formulation too. Some interesting conclusions regarding proper design of multidirectional stacks for delamination tests are drawn. Moreover, the results confirm the suitability of fully uncoupled multi-directional sequences for delamination tests. Thanks to their properties, these sequences might lay the foundations for the development of standard test procedures for delamination in angle-ply interfaces.

中文翻译：

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用于分层测试的完全解耦多向铺层的设计和有限元评估

在本文中，概述了获得分层试样的完全解耦多方向堆叠序列的程序。对于这样的序列，对于整个堆栈及其两个半部，平面内、膜弯曲和扭弯耦合项都是无效的（在经典层压板理论框架中的封闭形式解决方案中），它们在典型分层试样的预裂纹区域。这是根据适当的规则利用准平凡准齐次堆叠序列的叠加来实现的。可以获得嵌入分层平面的层的任何对取向。为了评估所提出方法的有效性，设计了一个完全解耦的多向序列，并将其与文献中提出的其他相关序列进行比较。双悬臂梁试验的有限元模拟也使用经典的虚拟裂纹闭合技术和经过修订的最先进的虚拟裂纹闭合技术公式进行。得出了关于分层测试的多向堆叠的正确设计的一些有趣的结论。此外，结果证实了完全解耦的多方向序列对分层测试的适用性。由于它们的特性，这些序列可能为角层界面分层标准测试程序的开发奠定基础。得出了关于分层测试的多向堆叠的正确设计的一些有趣的结论。此外，结果证实了完全解耦的多方向序列对分层测试的适用性。由于它们的特性，这些序列可能为角层界面分层标准测试程序的开发奠定基础。得出了关于分层测试的多向堆叠的正确设计的一些有趣的结论。此外，结果证实了完全解耦的多方向序列对分层测试的适用性。由于它们的特性，这些序列可能为角层界面分层标准测试程序的开发奠定基础。