TABLE OF CONTENTS Quality control for composites is often seen simply as validation of the physical and mechanical properties of the cured laminate. However, thorough control begins long before the part is completed and is more correctly termed process control overseeing its application is the task of quality assurance. Quality control involves control of the incoming material, control of the process, and finally, inspection for defects. [1], [2]
Section 11.2 presents an overview of the quality control of composites. Control of the cure process is especially important and is discussed in Section 11.3, where some of the current direct measurement methods of control are discussed.
Non-destructive inspection (NDI) is the final quality check on the finished part, and this is discussed in Section 11.4 . This section also covers inspection of service defects.
Most aerospace composite parts are manufactured by autoclave curing of prepreg, and the following discussion refers specifically to this fabrication route. Many of the quality requirements are, however, common to all fabrication processes.
[1]"Polymer Matrix Composites", Military Handbook, MIL-HDBK-17-ID, U.S. Department of Defense, 1994.
[2] Quality Control for the Manufacture of Composite Structures FAA Advisory Circular, AC 21 26, 1989.
The raw material for producing aerospace composites is usually obtained as pre-impregnated yarn, unidirectional tape, or fabric (frequently abbreviated to pre-preg) but quality control starts with the component materials of the pre-preg, namely the fibers and the resin.
Fiber testing is performed principally by the fiber manufacturer,...
