In this paper, the dynamic tensile properties of brittle materials were studied by using the dynamic Brazilian tests. Combined with a high‐speed photographic system, a split Hopkinson pressure bar (SHPB) was used to conduct dynamic Brazilian tests on three brittle materials: Al2O3 ceramic, granite and poly(methyl methacrylate). Based on the images recorded by a high‐speed camera, the displacement and strain fields were obtained by the digital image correlation method. The dynamic deformation and failure of the brittle materials were analysed. The rate‐related dynamic tensile strength of the three brittle materials was also determined and analysed. The results show that the dynamic Brazilian test is an effective method to study the dynamic tensile properties of brittle materials.
In this paper, the dynamic deformation of thin metal circular plates subjected to confined blast loading was studied using highspeed three-dimensional Digital Image Correlation (3D DIC). A small-scale confined cylinder vessel was designed for applying blast loading, in which an explosive charge was ignited to generate blast loading acting on a thin metal circular plate clamped on the end of the vessel by a cover flange. The images of the metal plates during the dynamic response were recorded by two high-speed cameras. The 3D transient displacement fields, velocity fields, strain fields and residual deformation profiles were calculated by using 3D DIC. Some feature deformation parameters including maximum out-of-plane displacement, final deflection, maximum principal strain and residual principal strain were extracted, and the result was in good agreement with that simulated by AUTODYN. A dimensionless displacement was introduced to analyse the effects of plate thickness, material types and charge mass on the deflection of metal plates. DIC is also proven to be a powerful technique to measure dynamic deformation under blast loading.
In this study, we report the analysis of a dynamic response process of a fiber-composite-reinforced shell when subjected to internal blast loading of different TNT equivalent by using a three-dimensional digital image correlation method. And it was compared with the dynamic response of the metal shell with the same TNT equivalent and the same surface density. We received the relationship between dynamic deformations and the sizes of the two shells under different TNT equivalence. Through comparison of the results, it was shown that the response process of the fiber-composite-reinforced shell was much more complex than that of the metal shell. Our experimental results suggest that the shock wave intensity, the material mechanical properties and the structure symmetry had important influences at different stages of the structural dynamic response. Fiber composites with high strength restricted the structural deformation extent and deformation rate. In addition, the interaction between fiber composite and metal liner reduced the probability of structural damage caused by the energy concentration. This work provides important insights for the design of cylindrical explosion vessels.
In this paper, the empirical mode decomposition-Hilbert Huang transform (EMD-HHT) was used to characterize the strain signal within metal cylindrical shell structure under internal blast loading. The received vibration frequencies of signal were closely consistent with FT characterization results. Through the EMD-HHT, instantaneous energy spectrum, marginal energy spectrum and Hilbert energy spectrum were determined, and these reflected the change in trend of signal energy in time domain, frequency domain, and time-frequency domain, showing the instantaneity and locality of explosion signal. The frequency components of the signal at any time were also determined, which proved that signals generated by the metal shell were the result of the superposition of different frequency signals under internal blast loading. This paper explains more clearly the time and frequency characteristics of blast signal, providing the theoretical basis for the study of antiknock in structures.
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