Experimental investigation of interfacial crack arrest in sandwich beams subjected to fatigue loading using a novel crack arresting device

Abstract

A recently proposed face-sheet–core interface crack arresting device is implemented in sandwich beams and tested using the Sandwich Tear Test configuration. Fatigue loading conditions are applied to propagate the crack and determine the effect of the crack stopper on the fatigue growth rate and arrest of the crack. Digital image correlation is used through the duration of the fatigue experiment to track the strain evolution as the crack tip advances. The measured strains are related to crack tip propagation, arrest, and re-initiation of the crack. A finite element model is used to calculate the energy release rate, mode mixity and to simulate crack propagation and arrest of the crack. Finally, the effectiveness of the crack arresting device is demonstrated on composite sandwich beams subjected to fatigue loading conditions.

Interfacial Crack Arrest in Sandwich Panels with Embedded Crack Stoppers Subjected to Fatigue Loading

“…Following on from and inspired by the work presented in [26][27][28], a new and significantly lighter design of the peel stopper was proposed and implemented in sandwich beams [26][27][28]. Initially, the conditions under which the novel peel stopper was able to deflect a propagating face-sheet/core interface crack were investigated in [26].…”

“…This study concerns the fatigue testing of sandwich panels with GFRP face-sheet and PVC foam core that have been fitted with embedded peel stoppers of the improved design introduced in [26,27,28]. The ability of the peel stoppers to enhance the damage tolerance of sandwich panels, i.e.…”

“…Three design variations of the peel stopper were tested showing that a design with glass fibres extruding from the tip of the peel stopper and extending into either the face-sheets or the face-sheet/core interface improved the interface crack deflection capabilities. The new peel stopper was further tested in sandwich beams using the Sandwich Tear Test (STT) in [27]. The aim of the research presented in [27,28] was to evaluate and validate the ability of the new lightweight peel stopper design to delay or hinder interface crack propagation, and ultimately achieving crack arrest in composite foam cored sandwich beams subjected to fatigue loading conditions.…”

“…The new peel stopper was further tested in sandwich beams using the Sandwich Tear Test (STT) in [27]. The aim of the research presented in [27,28] was to evaluate and validate the ability of the new lightweight peel stopper design to delay or hinder interface crack propagation, and ultimately achieving crack arrest in composite foam cored sandwich beams subjected to fatigue loading conditions. This was achieved and the underlying physical mechanisms were accounted for using both experimental and numerical approaches.…”

“…Divinycell H100 PVC foam from DIAB having a nominal density of 100 kg/m 3 [29] was used as the core material. This combination of composite face-sheets and core material was chosen, as it was used for the research presented in [27,28], from which the interface crack propagation properties are available. Table 1 summarizes the material properties of the sandwich panel specimens.…”