Considering their energy and resource efficiency, fiber-reinforced plastics (FRPs) have been displacing metals and metal alloys for lightweight constructions. During the semiautomated manufacturing process of FRPs, and in particular during the laying of reinforced fabric layers, foreign bodies are enclosed within them, which in turn reduce the mechanical performance of FRPs. The research project presented in this article investigated if the loss in mechanical properties, such as tensile, flexural, and impact strengths, depends on the position of defined local defects, polytetrafluorethylene (PTFE) in this case, in the thickness direction of FRPs. In order to achieve this aim, PTFE was placed in different layers of reinforcing fabric before infusion. Subsequently, the mechanical performance of the fabricated FRPs was tested and evaluated. On the basis of the experiment, it can be concluded that the loss in mechanical properties was maximal if PTFE was laid in the middle position of FRPs in the thickness direction.
 Gholizadh S. (2016). A review on non-destructive testing methods of composite materials. In: Proceedings. XV Portuguese Conference on Fracture, PCF 2016, 10-12 February 2016, Paco de Arcos, Portugal.
 Heslehurst RB. (2014). Defects and damage in composite materials and structures. New York: Taylor & Francis Group, ISBN 978-1-1380-7369-2.
 Mesogitis TS, Skordos AA, Long AC. (2014). Uncertainty in the manufacturing of fibrous thermosetting composites: A review. Composites Part A: Applied Science and Manufacturing, 57, 67–75.
 Zöcke C, Langmeier A, Stössel R, Arnold W. (2007). Quantitative Auswertung von Fehlstellen an Bauteilen aus Faserverbundwerkstoff mit Lock-In Thermographie. Thermografie-Kolloquium 2007 - Vortrag 17.
 Kochan A. (2011). Untersuchungen zur zerstörungsfreien Prüfung von CFK-Bauteilen für die fertigungsbegleitende Qualitätssicherung im Automobilbau. Dissertation, Technical University of Dresden, Germany.
 Ray BC, Hasan ST, Clegg DW. (2007). Evaluation of defects in FRP composites by NDT techniques. Journal of Reinforced Plastics and Composites, 26(12), 1187-1192.
 Pekbey Y, Sayman O. (2006). A Numerical and Experimental Investigation of Critical Buckling Load of Rectangular Laminated Composite Plates with Strip Delamination. Journal of Reinforced Plastics and Composites, 25(7), 685-697.
 Ashir M, Nocke A, Cherif C. (2018). Influence of defined amount of voids on the mechanical properties of carbon fiber-reinforced plastics. Polymer Composites. published online 7 March 2018. doi: 10.1002/pc.24820.
 Tartare M, Rebuffel V, Ducros N, Verger L. (2014). Dual and Multi-energy Radiography for CFRP Composites inspection. 11th European Conference on Non-Destructive Testing (ECNDT 2014), October 6-10, 2014, Prague, Czech Republic.
 Poudel A, Shrestha SS, Sandhu JS, Chu TP, Pergantis CG. (2015). Comparison and analysis of Acoustography with other NDE techniques for foreign object inclusion detection in graphite epoxy composites. Composites Part B: Engineering, 78, 86-94.
 Barry TJ, Kesharaju M, Nagarajah C. (2016). Defect characterisation in laminar composite structures using ultrasonic techniques and artificial neural networks. Journal of Composite Materials, 50, 861-871.
 Heuer H, Schulze M, Pooch M, Gäbler S, Nocke A, Bardl G, Cherif C, Klein M, Kupke R, Vetter R, Lenz F, Kliem M, Bülow C, Goyvaerts J, Mayer T, Petrenz S. (2015). Review on quality assurance along the CFRP value chain – Nondestructive testing of fabrics, preforms and CFRP by HF radio wave techniques. Composites Part B: Engineering, 77, 494-501.
 Liu B, Zhang H, Fernandes H. (2016). Quantitative Evaluation of Pulsed Thermography, Lock-in Thermography and Vibrothermography on Foreign Object Defect (FOD) in CFRP. Sensors, 16(5), 743. doi:10.3390/s16050743.
 Cherif C. (2016). Textile Materials for Lightweight Constructions: Technologies-Methods-Materials-Properties. Berlin, Heidelberg: Springer-Verlag GmbH, ISBN 978-3-662-46340.