Typical characteristics of counterintuitive behavior in thin aluminum plates under blast loading

Experimental and numerical investigations on the response of thin aluminum plates to airblast loading for varying structural and loading parameters are presented. The loading was generated by detonating explosive at various standoff distances. The permanent midpoint displacement of each plate was measured in tests to ascertain deformation profiles. Relying on the experimental results, numerical models developed in LS-DYNA provided accurate description to predict the entire range of structural response at various standoff distances. Special focus is placed on the influence of structural and loading parameters on counterintuitive behavior (CIB). The analysis reveals that the characteristics of CIB are extremely sensitive to the mentioned parameters. The CIB region trends to be wider as thickness decreased and load intensity increased. The critical point between IB and CIB inclines to locate in larger standoff distance with reduced plate thickness and increased load strength. It is confirmed that the CIB response is controlled by the ratio of positive phase duration to natural period of vibration noted as normalized duration. The relationship between normalized duration of the critical point (t₊/T_n)_c and charge mass W was derived to predict the occurrence of CIB. The structural response categories and oscillation behaviors on blast loaded plates were also briefly discussed. Furthermore, when considering the CIB plates, the energy partitioning between kinetic energy and internal energy based on simulations and relevant discussions were presented to reveal the occurrence.