Acoustic Emission (AE) is casually employed for monitoring the mechanical behaviour of composite media as the amount of damage and the different fracture modes can be well characterised through the evolution of the AE characteristics. However, the sensitivity of the technique allows for more than just classification of the existing damage modes in composite materials. In the present paper, the limits of AE are further pushed as it is used to characterise the stress/strain field developing in composite laminates even before damage mechanisms become evident. In addition, the change of the strain field due to damage evolution during quasi-static and fatigue experiments, as monitored by real-time Digital Image Correlation (DIC), is depicted on the shift of the AE parameters. This is of great importance in cases that detrimental shear stresses are generated in the material, leading to important interlaminar delaminations and mechanical deterioration. AE can be used in this direction to predict the upcoming damage modes and to take the necessary measures to avoid final catastrophic failure by applying intermediate repair approaches. The examined material in this study is angle-ply Carbon Fibre Reinforced Polymer (CFRP) composite laminates consisting of different off-axis plies, in which different multiaxial conditions are generated due to the inherent anisotropy of composite materials. It is demonstrated that AE can identify the dominant stress/strain component rather than just the occurring damage mode even at early loading stages, before severe fracture influences the mechanical capacity of the material.

v© 2020 The Authors. Published by Elsevier Ltd.

声发射（AE）随便被用于监视复合介质的机械性能，因为损伤的程度和不同的断裂模式可以通过AE特性的演变得到很好的表征。但是，该技术的敏感性不仅仅可以对复合材料中现有的损坏模式进行分类。在本文中，甚至在损伤机理尚未显现之前，AE的极限就被进一步推高，因为它被用来表征复合材料层合板中出现的应力/应变场。另外，通过实时数字图像相关性（DIC）监控，在准静态和疲劳实验过程中，由于损伤演化而引起的应变场变化在AE参数的移动上进行了描述。这在材料中产生有害的剪切应力，导致重要的层间分层和机械劣化的情况下非常重要。通过应用中间修复方法，可以在此方向上使用AE来预测即将到来的损坏模式并采取必要的措施来避免最终的灾难性故障。本研究中检查的材料是由不同的离轴层组成的角层碳纤维增强聚合物（CFRP）复合层压板，其中由于复合材料的固有各向异性而产生了不同的多轴条件。结果表明，在严重断裂影响材料的机械性能之前，即使在早期加载阶段，AE仍可以识别主要的应力/应变分量，而不仅仅是出现的破坏模式。

v©2020作者。由Elsevier Ltd.发布