The dynamic response of blast-loaded steel plates is studied both experimentally and numerically. The blast loading was generated using a shock tube facility. This is an alternative to explosive detonations where the blast intensity is easily controlled through the initial conditions in each experiment. Massive and deformable steel plates where located at the tube end during testing, where the massive-plate tests served as a basis for comparison with respect to fluid-structure interaction (FSI) effects. Special focus was placed on the influence of pre-formed holes on the dynamic response and failure characteristics of the deformable plates. The plates had an exposed area of 0 0.3 m .3 m and the tests covered a wide range of structural responses from large inelastic deformations to complete tearing along the diagonals of the plates. Numerical simulations were performed in the finite element code EUROPLEXUS, where the plate was uniformly loaded by the pressure measurements from the massive-plate tests. The plate deformation and the observed crack propagation were successfully recreated by using element erosion and adaptive mesh refinement in the plate, driven by the damage parameter in the material model. As expected, the simulations overestimated the plate deformations due to the underlying assumption that the blast pressure was uncoupled from the deformation (i.e., neglecting FSI). It was also found that the modelling of the realistic boundary conditions with clamping frames, contact and friction was essential to predict the experimental results.
The inelastic response of thin aluminium and steel plates subjected to airblast loading is studied numerically and validated against experimental data. Special focus is placed on the influence of elastic effects and negative phase on the structural response. The blast loading was varied by detonating spherical charges of plastic explosives at various stand-off distances relative to the centre point of the plates. The numerical results obtained with the finite element code EUROPLEXUS were in good agreement with the experiments and predicted the entire range of structural response from complete tearing at the supports to a more counter-intuitive behaviour (CIB) where the final configuration of the plate was in the opposite direction to the incident blast wave due to reversed snap buckling (RSB). RSB attracted special attention since this is an unstable configuration sensitive to small changes in the loading and in structural characteristics. The negative phase of the blast pressure is usually neglected in blast-resistant design. However, the numerical simulations showed that the negative overpressure dominated the structural response and led to RSB at some loading and structural conditions. Two distinctive types of CIB were identified and both were found to depend on the timing and magnitude of the peak negative overpressure relative to the dynamic response of the plates. The study also revealed that CIB may occur in thin plates when the negative impulse is of the same order of magnitude as the positive impulse. The partial and complete failure along the boundaries observed in some of the tests was also successfully recreated in the simulations by using an energy-based failure criterion and element erosion.
The determination of the blast protection level of laminated glass windows and facades is of crucial importance, and it is normally done by using experimental investigations. In recent years numerical methods have become much more powerful also with respect to this kind of application. This paper attempts to give a first idea of a possible standardization concerning such numerical simulations. Attention is drawn to the representation of the blast loading and to the proper description of the behaviour of the material of the mentioned products, to the geometrical meshing, and to the modelling of the connections of the glass components to the main structure. The need to validate the numerical models against reliable experimental data, some of which are indicated, is underlined.
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