Probability of Detection Analysis of Air-coupled Ultrasound Inspection of Thermoplastic CFRP Tapes

Essig, Wolfgang; Institut für Kunststofftechnik - University of Stuttgart; Germany

Essig, W.; Institut für Kunststofftechnik, University of Stuttgart; Germany
Rittmann, J.; Institut für Kunststofftechnik, University of Stuttgart; Germany
Kreutzbruck, M.; University of Stuttgart; Germany

ID: ECNDT-0518-2018
Download: PDF
Session: Composite General 1
Room: G1
Date: 2018-06-11
Time: 14:30 - 14:50

Besides the aerospace industry, fiber reinforced plastics have also spread towards many further applications such as automotive or civil engineering. Their superior strength and stiffness to mass ratio made them the number one material for achieving high performance. Especially continuous fiber reinforced plastics allow for the construction of structures which are custom tailored to their mechanical loads. The two main constituents of CFRP are carbon fibers and matrix. Two possibilities for matrix material exist: thermosetting and thermoplastic matrix. While thermosetting matrix may yield better properties, thermoplasticity opens a wide range of applications due to weldability and compatibility to e.g. thermoplastic injection molding materials.
In this work we report on a Probability of Detection Analysis (PoD-Analysis) of an air-coupled ultrasound Inspection of thermoplastic CFRP tapes. Several preliminary works were performed in order to optimize the data set being involved within the PoD-Analysis. The influence of the tape temperature on the ultrasonic transducers and the behavior of the ultrasonic signal in thermoplastic tape at elevated temperature of up to 210 °C was examined in a specially developed testing rig. For maximizing the resolution of ultrasonic transmission measurements a cone design was developed. Special emphasis was given to both the achievable signal-to-noise ratio and the spatial resolution. Different types of artificial defects such as cuts through and half through the thickness, holes, and areas of different impregnating states were introduced into the tapes. The POD was also determined for different production parameters such as tape velocity and tape thickness.