Abstract
The dynamic mode-II energy release rate (ERR) of the end-loaded split (ELS) test with applied time-dependent displacement is derived for the first time with the effect of vibration included. Dynamic Euler-Bernoulli beams are used together with a deflection condition to simulate contact. To understand the dynamic effect and the relative dynamic contribution from each vibration mode, a ‘dynamic factor’ and a ‘spatial factor’ are defined. It is found that the contribution of the ith vibration mode is dependent on the spatial factor, which is a function of the delamination length and the total length of the ELS specimen. Certain vibration modes are dominant dependent on the spatial factor. In addition, for a given spatial factor, there may be a certain vibration mode, which makes approximately zero contribution to the ERR. The developed theory is verified against results from finite-element method (FEM) simulations and it is in excellent agreement. This work now allows the loading rate-dependent mode-II delamination toughness of materials to be determined by using ELS tests. In addition, it provides understanding of the structural dynamic response in the presence of mode-II delamination and can guide the design of structures to mitigate against vibration-driven delamination.
Highlights
Laminated composite materials are widely used in aerospace, automotive and naval applications to save weight
The dynamic effect and the contribution of each vibration mode were quantified by defining a ‘dynamic factor’ and a ‘spatial factor’
It was found that dynamic factor decreased with time as it oscillated around the dynamic factor-contribution of the dominant vibration mode
Summary
Laminated composite materials are widely used in aerospace, automotive and naval applications to save weight. Following Smiley and Pipe’s [6] general method, Blackman et al [8] analytically modeled the end-loaded split (ELS) specimen and derived that the dynamic contribution to the ERR varied between approximately − 1.5ρhv and 1.8ρhv, depending on the ratio of the delamination length to the total length of the ELS specimen. Each of these models [6,7,8] is ground-breaking in its own right and provides valuable insight on dynamic fracture behavior, none of them account for the transient effects associated with structural vibration and wave propagation.
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