Experimental and FE investigations on the influential parameters in positioning and measurement of strain gauges in adhesively bonded single lap joints
M.Z. Sadeghi, Josef Weiland, J. Zimmermann, Alexander Schiebahn, Uwe Reisgen, Kai‐Uwe Schröder
Abstract
Using backface strain gauge is a very common technique for structural health monitoring in the adhesively bonded joints while loading. Finite Element (FE) techniques used for failure prediction of such joints are normally validated against failure load not strain measurements. However, backface strain measurement can be highly influenced by different parameters (such as tolerance in the thickness of the bondline, strain gauge misalignment, etc.). In this work, the applicability of a new location for placing the back-face strain gauges on the adhesively bonded single lap joints (SLJs) for damage detection is examined. This location is based on the undamaged (healthy) state of the joint and is independent of the applied load. SLJs were tested under quasi static tension loading. FE models were developed for validating the variation of longitudinal strain on the bondline of the joint against experimental tension quasi-static tests. The influence of different parameters -which are inevitable in the assembly process and testing the joint- on strain measurement is investigated.