复合材料分层损伤微区应变测量及声发射统计特征
发布时间：2018-12-11 05:03
【摘要】：实现复合材料分层损伤演化的准确表征是一项巨大的挑战,本文针对复合材料层合板结构在服役过程中易出现分层的问题,采用声发射动态监测和声发射信号统计分析方法即幅度谱、声发射动态监测和应变电测耦合分析以及声发射动态监测和数字图像相关的互补的无损检测技术研究复合材料试件分层损伤演化失效行为。通过实验获得载荷曲线、声发射幅度、相对能量等,再结合声发射统计分析方法以及微区应变测量方法,对实验结果进行力学性能、层间界面破坏表征和声发射特征信号响应行为等分析研究,进而得到复合材料层合板的机械性能、声发射响应行为及其损伤破坏机制,得到的主要结论如下:(1)对于复合材料Ⅱ型分层损伤弯曲失效,实验结果表明裂纹尖端部位的微损伤累积对分层试件演化失效过程具有很大的影响,并且分层损伤的物理机制源自分层微结构损伤演化如基体开裂、脱粘和纤维断裂等。此外,声发射特征信号和幅度谱准确地描述了含Ⅱ型分层复合材料从微损伤到宏观断裂的演化过程,表征了分层微观结构损伤的物理机制,本实验结果为同时研究复合材料结构微损伤机制和损伤动态响应的评估提供了新思路。(2)对于复合材料圆形分层损伤压缩失效,实验结果表明在压缩载荷作用下,两类分层直径(5mm和10mm)试件的破坏路径基本一致、层间破坏机理相同。分层缺陷面积的大小对试件的承载能力有较大影响,分层缺陷面积越大,试件的承载能力降低,试件的破坏程度加剧。当分层缺陷位于复合材料层合板表层时,较薄子层的屈曲对分层大小不敏感。声发射信号可作为判定复合材料分层损伤状态的有效依据,复合材料分层的不稳定扩展对应着较多高幅值、高能量、持续时间长的声发射信号。此外,载荷-纵向应变曲线由线性变化到近似线性变化再到非线性变化的过程与声发射信号分析结果较吻合。(3)对于复合材料多分层损伤压缩屈曲失效,实验结果表明多分层复合材料试件压缩屈曲过程可以分为分层张开,局部屈曲和整体屈曲失效三个阶段。复合材料结构多分层损伤的大小、位置及子层厚度将严重影响复合材料试件压缩屈曲失效载荷的大小。声发射信号幅度、持续时间和相对能量等特征参数可以表征多分层复合材料试件损伤的萌生、累积与扩展过程。此外,数字图像相关是研究复合材料结构微位移场和应变场非常优秀的方法,可以准确表征典型分层区域的变形和应变。声发射和数字图像相关互补的无损检测技术可以准确监测和表征复合材料结构的损伤源。
[Abstract]:It is a great challenge to accurately characterize the delamination damage evolution of composite materials. In this paper, delamination is easy to occur in the service of composite laminates. The dynamic monitoring of acoustic emission and the statistical analysis method of acoustic emission signal, namely amplitude spectrum, are adopted. Dynamic acoustic emission (AE) dynamic monitoring and strain-electric measurement coupled analysis, acoustic emission dynamic monitoring and digital image related complementary nondestructive testing (NDT) techniques are used to study the delamination damage evolution failure behavior of composite specimens. The load curve, the amplitude of acoustic emission, the relative energy and so on are obtained through experiments. The mechanical properties of the experimental results are obtained by combining the statistical analysis method of acoustic emission and the method of strain measurement in micro-region. The mechanical properties, acoustic emission response behavior and damage mechanism of composite laminates are obtained by analyzing the interlaminar interface failure characterization and acoustic emission characteristic signal response. The main conclusions are as follows: (1) for the flexural failure of type 鈪，
本文编号：2371924
[Abstract]:It is a great challenge to accurately characterize the delamination damage evolution of composite materials. In this paper, delamination is easy to occur in the service of composite laminates. The dynamic monitoring of acoustic emission and the statistical analysis method of acoustic emission signal, namely amplitude spectrum, are adopted. Dynamic acoustic emission (AE) dynamic monitoring and strain-electric measurement coupled analysis, acoustic emission dynamic monitoring and digital image related complementary nondestructive testing (NDT) techniques are used to study the delamination damage evolution failure behavior of composite specimens. The load curve, the amplitude of acoustic emission, the relative energy and so on are obtained through experiments. The mechanical properties of the experimental results are obtained by combining the statistical analysis method of acoustic emission and the method of strain measurement in micro-region. The mechanical properties, acoustic emission response behavior and damage mechanism of composite laminates are obtained by analyzing the interlaminar interface failure characterization and acoustic emission characteristic signal response. The main conclusions are as follows: (1) for the flexural failure of type 鈪，
本文编号：2371924
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