Nondestructive Testing of Graphite Fiber Composite Structures

This paper discusses nondestructive testing (NDT) methods and techniques for detection of material and manufacturing anomalies in state-of-the-art graphite composites. Introduction of composites into large-scale production depends in large measure on the successful application of NDT for process control and monitoring. Visual, liquid-penetrant, radiographic, ultrasonic, sonic, thermal, and acoustic-emission NDT methods are used to evaluate graphite fiber composite aircraft specimens and structures. Reference standards are fabricated with built-in discontinuities, commensurate with each structural article fabricated. The test specimens and parts were tested by various methods in order to determine optimum discontinuity detection. Tests were conducted on research and development graphite composite aircraft structures consisting of (1) molded graphite flap ribs, (2) graphite composite flap assembly, and (3) graphite composite horizontal stabilizer assembly.