RIMI: Fast Detection of Flaws and Residual Stresses in Composite Materials by a Real-Time Nondestructive Laser Technique

纤维增强有机基复合材料正被用作或提议作为许多军事和商业应用的主要和次要结构。这些复合材料中存在的缺陷和残余应力通常是由制造和/或安装过程引起的。此外，众所周知，这些先进材料的结构行为受到使用中的环境条件(湿度、温度、压力、冲击等)的影响。这些条件会导致复合材料中的残余应力和微裂纹，并可能不可逆转地破坏纤维/基质界面。这项研究旨在开发和展示一种新的自动化无损检测技术-激光散斑剪切干涉法，该技术能够快速确定复合材料中的残余应力和定位缺陷。通过允许在现场进行基本的实时测量，可以实现工程模型的开发，从而有助于改进各种操作条件下的复合材料的基础研究。这项技术是可行的，适合在制造环境或部门/维修设施和现场操作。两名少数族裔本科生和一名工程学研究生将协助首席调查员进行拟议的研究。

Fiber reinforced organic matrix composites are being used or proposed as primary and secondary structures for numerous military and commercial applications. The presence of flaws and residual stresses in these composites are often caused by the fabrication and/or installation process. Moreover, the structural behavior of these advanced materials is known to be affected by in-service environmental conditions (humidity, temperature, pressure, impact, etc.). These conditions induce residual stresses and microcracking in the composite, and can irreversibly degrade the fiber/matrix interface. The proposed research is designed to develop and demonstrate a novel automated NDE technique, laser speckle shearing interferometry, capable of rapidly determining the residual stresses and locating flaws in composites. By allowing fundamental real-time measurements to be made in situ, the development of engineering models can be attained, and thus will contribute to improved basic studies of composite materials under various operational conditions. The technique is viable and suitable for operation in a manufacturing environment or dept/repair facility and in the field. Two minority undergraduate students and one graduate student of engineering will assist the principal investigator in the proposed research.