NSF Young Investigator: Nondestructive Evaluation of Polymer Composites

9457156曼特尔这项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结合。将采用机载声学超声技术对胶带铺设进行闭环控制。在这项研究的早期阶段，重点将是更好地了解机载超声波，以检测复合材料中的缺陷。将建立一个将机载声学-超声操作参数与所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式无损检测方法离线检测和评估粘接质量。最顶层粘结不良的不同厚度的试件将被制造和测试。粘结强度的无损评估将与粘结强度的机械测试进行比较。在最后阶段，建议的空气接触式无损检测方法将集成到现有的磁带铺设设备中。根据实验技术的统计设计，将建立经验过程模型并实施闭环控制算法。这项研究在几个方面都具有重要意义。在通过原位固结加工先进材料的过程中，充分的层间粘结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监控零件质量。在加工过程中发现的缺陷可以立即返工，作为工艺控制方案的一部分；从而提高产量，减少废品和成本。一种非接触式方法还提供了到远程站点的便携性和在线(在制造期间)传感功能。此外，类似的方法也可应用于其他原位固结和粘结过程。

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.