*Article* **Effect of the Test Procedure and Thermoplastic Composite Resin Type on the Curved Beam Strength**

**Robin Hron \*, Martin Kadlec and Roman R ˚užek**

Materials and Technologies Department, Aviation Division, VZLU-Czech Aerospace Research Centre, 199 05 Prague, Czech Republic; kadlec@vzlu.cz (M.K.); ruzek@vzlu.cz (R.R.) **\*** Correspondence: hron@vzlu.cz; Tel.: +420-604-829-041

**Abstract:** The application of thermoplastic composites (TPCs) in aircraft construction is growing. This paper presents a study of the effect of an applied methodology (standards) on out-of-plane interlaminar strength characterization. Additionally, the mechanical behaviour of three carbon fibre-reinforced thermoplastic composites was compared using the curved beam strength test. Data evaluated using different standards gave statistically significantly different results. The study also showed that the relatively new polyaryletherketone (PAEK) composite had significantly better performance than the older and commonly used polyphenylensulfid (PPS) and polyetheretherketone (PEEK). Furthermore, considering the lower processing temperature of PAEK than PEEK, the former material has good potential to be used in serial aerospace production.

**Keywords:** composite; thermoplastic; interlaminar strength; polyphenylensulfid; polyetheretherketone; polyaryletherketone; curved beam
