Future Directions Relative to NDE of Composite Structures

One of the key elements of increasing the affordability of major weapons systems is reducing costs associated with manufacturing. Nondestructive evaluation (NDE) is a critical element of the manufacturing process and one that cannot be compromised. A key goal associated with NDE research and development is to help reduce the cost associated with quality assurance. In relation to composite structures, this is being approached from several directions, two of which will be discussed. The approach most frequently used for inspection of composite parts is to pull the parts out of the manufacturing cells and route them to a centralized quality assurance area for inspection. This approach leads to accumulation of non-recurring costs for tooling/fixturing to support the inspection and significant additions to production flow time. An alternative would be to develop nondestructive evaluation processes that can be performed in the manufacturing cells. The keys to successful implementation are: (1) demonstrating the ability to perform the inspection of parts while still on the tool and (2) establishing a methodology for porosity evaluation using single-sided inspection data. Technology developed for in-service inspections of aircraft, where single-sided access is the norm, is now being considered for this “in-process” inspection approach as well. Automated manufacturing processes, such as fiber placement, are now being used for manufacturing of large and/or complex composite parts. Automated processes open up opportunities to incorporate inspection into the manufacturing process, eliminating post-process inspection. Gap and overlap detection, a process typically performed manually after each ply is placed, can now be performed using an optical process, significantly reducing machine down time. Applications identified for each approach will be discussed.