An investigation of in-plane dynamic behavior of adhesively-bonded composite joints

What is it about?

This study examines the behaviour of adhesively-bonded composite joints under dynamic compression tests. The purpose of this work is to use the split Hopkinson pressure bar (SHPB) for the dynamic characterization of adhesively bonded joints subjected to in-plane compression loading and in particular, the effect of strain rate on the mechanical behaviour and the damage kinetics. These joints are studied using glass/vinylester composite materials which are frequently used in naval applications Compression tests are performed at different strain rates using SHPB and high speed camera has been used to follow the damage progression. The experimental results have shown that the dynamic properties change with respect to the change in strain rate. Fibre buckling and delamination are the main damage criterias seen in the specimens under in-plane compressive tests. Therefore, this study not only allows us to understand the dynamic response of the adhesively bonded joints under dynamic compression but also enables us to establish damage models based on strain rate effect, for structure design purposes.

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Why is it important?

In the course of this study, an experimental approach was implemented with an aim of investigating the in-plane dynamic mechanical behavior of an adhesively bonded composite joints. Samples were tested at four different impact pressures of 1, 2, 3, 4 bar and strain rates of 210, 312, 528, 713 s−1 respectively with SHPB apparatus. It has been concluded that materials have shown a strength dependency on strain rate and there is considerable increase in dynamic parameters with the increase in the strain rate. Based on experimental results, empirical laws have been formulated linking the dynamic properties of the adhesively bonded joints with the strain rate. The compressive failure modes for in in-plane loading of specimens were successfully observed in real time compression tests using high-speed photography camera at a farming rate of 50,000 images per second. As the strain rate increases more damage modes can be seen i.e. matrix cracks, delamination and failure of adhesive interlayer. Specimens fail due to laminate splitting at low strain rates, with delamination and adhesive/adherent interfacial separation dominating the high strain rate failure mode.

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