NSF Young Investigator: Nondestructive Evaluation of Polymer Composites

本研究的目标是开发和实施一种非接触、非破坏性的方法来评估复合材料原位固结过程中的层间粘合。将一种机载声-超声技术应用于胶带敷设的闭环控制。在这项研究的早期阶段，重点将放在更好地理解用于检测复合材料缺陷的机载超声波上。将建立一个将机载声超声工作参数与产生的应力波联系起来的理论模型，并进行实验验证。研究的第二阶段将需要使用拟议的空气接触无损检测方法离线检测和评估债券质量。将制造和测试具有最上层粘合不良的不同厚度的样品。结合强度的无损评价将与结合强度的力学试验进行比较。在最后阶段，建议的空气接触无损检测方法将集成到现有的胶带铺设设备中。在实验技术的统计设计之后，将建立一个经验过程模型并实现闭环控制算法。这项研究在几个方面都很重要。在通过原位固结加工先进材料时，充分的层间粘合对零件结构的完整性至关重要。由于这些材料的成本很高，因此需要在加工过程中对零件质量进行监控。在加工过程中发现的缺陷可以作为过程控制方案的一部分立即返工；从而提高产量，减少废料和成本。非接触式方法还提供了远程站点和在线（制造过程中）传感能力的可移植性。此外，类似的方法可以应用于其他原位固结和粘接过程。

9457156 Mantell The goal of this research is to develop and implement a noncontact, nondestructive method for evaluating interlaminar bonding during in-situ consolidation of composites. An airborne acousto-ultrasonic technique will be implemented in closed loop control of tape laying. In the early phases of this research, the focus will be on developing a better understanding of airborne ultrasonic waves for detecting defects in composites. A theoretical model relating airborne acousto-ultrasonic operating parameters to the resulting stress wave will be developed and experimentally validated. The second phase of the research will entail sensing and evaluating bond quality off line using the proposed air contact NDE method. Specimens of varying thickness with an poorly bonded top most layer will be manufactured and tested. Nondestructive evaluation of bond strength will be compared with mechanical tests of the bond strength. In the final phase, the proposed air contact NDE method will be integrated into an existing tape laying apparatus. Following statistical design of experiment techniques, an empirical process model will be developed and a closed loop control algorithm implemented. This research is significant on several fronts. In processing of advanced materials via in-situ consolidation, adequate interlaminar bonding is critical to part structural integrity. Because cost of these materials is high, it is desirable to monitor part quality during processing. Defects identified during processing can be reworked immediately as part of the process control scheme; thereby improving yields and reducing scrap and costs. A noncontact method also offers portability to remote sites and on line (during manufacture) sensing capabilities. Moreover, similar methodologies could be applied to other in-situ consolidation and bonding processes.