Qualitative comparison of non-destructive methods for inspection of carbon fiber-reinforced polymer laminates. (November 2020)

• Record Type: Journal Article
• Authors: Rus, Janez; Gustschin, Alex; Mooshofer, Hubert; Grager, Jan-Carl; Bente, Klaas; Gaal, Mate; Pfeiffer, Franz; Grosse, Christian U.
• Is Part Of: Journal of composite materials. Volume 54:Number 27(2020)
• Page Start: 4325
• Page End: 4337
• Publication Date: 2020-11
• Subjects: Carbon fiber-reinforced polymer -- air-coupled ultrasound -- optically excited lock-in thermography -- X-ray micro-computed tomography -- X-ray dark-field radiography; Composite materials -- Periodicals; Composites -- Périodiques; 620.118
• DOI: 10.1177/0021998320931162
• Languages: English
• ISSNs: 0021-9983

Abstract

In the rapidly expanding composite industry, novel inspection methods have been developed in recent years. Particularly promising for air-coupled testing are cellular polypropylene transducers which offer better impedance matching to air than piezoelectric transducers. Furthermore, broadband transmitters (laser-induced ultrasound and thermoacoustic emitters) and receivers (optical microphones) have opened a completely new chapter for advanced contact-free ultrasound inspection. X-ray dark-field radiography offers a different approach to detect porosity and microcracks, employing small angle X-ray scattering. These innovative ultrasonic and radiographic alternatives were evaluated in comparison with well-established inspection techniques. We applied thirteen different non-destructive methods to inspect the same specimen (a carbon fiber-reinforced polymer laminate with induced impact damage): air-coupled ultrasound testing (using piezoelectric transducers, broadband optical microphones, cellular polypropylene transducers, and a thermoacoustic emitter), laser-induced ultrasound testing, ultrasonic immersion testing, phased array ultrasonic testing, optically excited lock-in thermography, and X-ray radiography (projectional absorption and dark-field, tomosynthesis, and micro-computed tomography). The inspection methods were qualitatively characterized by comparing the scan results. The conclusions are advantageous for a decision on the optimal method for certain testing constraints.