Detection of Pin Failure in Carbon Fiber Composites Using the Electro-Mechanical Impedance Method

Abstract

<jats:p>This paper presents a proof of concept for simultaneous load and structural health monitoring of a hybrid carbon fiber rudder stock sample consisting of carbon fiber composite and metallic parts in order to demonstrate smart sensors in the context of maritime systems. Therefore, a strain gauge is used to assess bending loads during quasi-static laboratory testing. In addition, six piezoelectric transducers are placed around the circumference of the tubular structure for damage detection based on the electro-mechanical impedance (EMI) method. A damage indicator has been defined that exploits the real and imaginary parts of the admittance for the detection of pin failure in the rudder stock. In particular, higher frequencies in the EMI spectrum contain valuable information about damage. Finally, the information about damage and load are merged in a cluster analysis enabling damage detection under load.</jats:p>

Detecting damage in rudder stocks under load using electro-mechanical susceptance: Frequency-warping and semi-supervised approaches

“…The measured data from the bending study has been presented previously (Moll et al, 2020a) and portions of the data from the combined bending/torsion experiments have also appeared as a recent conference contribution (Moll et al, 2020b). However, only the measurement results have been published, all other parts of the present work represent novel and original content.…”

“…pristine, load, damage), the all-to-all distances between the spectra are evaluated and shown in Figure 6. The all-to-all dissimilarity matrices are an continuation and also extension of the DI-based perspective (Moll et al, 2020a(Moll et al, , 2020b where merely the distance to the initial baseline measurements has been taken into account.…”

“…On a few points the membership is ambiguous: For measurement index 4 in the binding study and for the indices 40-42 in the combined bending/torsion study, the assignment is inconsistent across the three transducers. Based on the previous works (Moll et al, 2020a(Moll et al, , 2020b, it becomes evident that the inconsistent membership assignment arises for those measurement indices, that is, those points in time, where a damaging of the rudder stocks happens. Since those measurement The high frequencies are depicted where the influence of applied loads is easily visible.…”

“…Details of the experimental setup regarding the first study on bending and of the second study combining bending with torsion can be found in (Moll et al, 2020a) and (Moll et al, 2020b), respectively. For the sake of completeness, the essential facts are however re-stated here.…”

“…In the present work, previous studies on bending (Moll et al, 2020a) and combined bending with torsion (Moll et al, 2020b) are complemented. They consider rudder stocks which are frequently encountered in the maritime industries.…”