Experimental Study On The Dynamic Response Of Plated And Shell Structures Subjected To Blast Loading

The dynamic responses of the structure subjected to blast loading are very complex.The measurents of the displacement,strain and velocity of the object during the impact loading process,are important for the study on the dynamic mechanical behavior,deformation and failure mechanism of the structure or materials.Conventional measurement techniques,such as strain gauges,VISAR or DISAR,can only provide limited motion or deformation information for a single point or a few points at the same time.Digital image correlation(DIC has been considered as one of the most popular and important optical techniques for full-field motion,deformation and shape measurements in experimental mechanics.In this study,a series of experimental studies are performed for ivestigating the dynamic responses of metallic plates subjected to the air and underwater shock wave,and the vibration responses vessel structures subjected to impluse loading.3D DIC technology was applied to the full-field measurent of the deformation and rupture of the plated and shell structures subjected to shock wave loading.The error of measurement in this system was discussed with different source factors.Through the tests for calibration of error,the effect of the size of calibration panel,the amount of images for calibration,and the position of the calibration panel were studied,as well as the effect of the temperature of the image Sensor on the error.A serial of standard calibration steps were given,and a preheat precaution was supplied to eliminate the effect of camera's temperature.In order to restrict the detonation products and strong light,a confined blast-loading device was designed,for the study on the dynamic deformation and rupture behaviours of the copper,brass and titanium alloy thin plates subjected to air blast loading.The dynamic deformation of the metal plates was numerically simulated using AUTODYN finite element code,and the simulated result was in good agreement with the experimental results measured by 3D DIC.In addition,the functional mechanism of the blast shock wave reflection and internal quasi-static pressure on the plate were studied by a pressure experiment.The oscillation frequency characteristics of the plate during the damping vibration period were analyzed through the modal analysis.The relationships between the dynamic deformation of metal plates,their propertiesand material types,pre-cracks and the blast loading intensity were discussed using a dimensional analysis.An empirical equation was proposed to predict the dynamic deflection of metal plates subjected to air blastloading.The dynamic response of air-backed panel subjected to underwater impulsive loading has been studied.The equivalent FSI device(fluid–structure interaction),consist of a gas gun and a water anvil tube,was used to provide an exponentially decaying pressure in lieu of explosive detonation acted on the panel specimen.The transient responses of the panels were measured by a High-speed three-dimensional Digital Image Correlation(3D DIC)photography system.The influences of intensity of loading,support condition,pre-cracks,materials and thickness on the deformation of specimen panels were discussed.The dynamic deformation of the metal plates was numerically simulated using AUTODYN finite element code,and the simulated result was in good agreement with the experimental results.Based on the DIC results,the Rajendran empirical formula was verified combining with the dimension analysis,and a new empirical equation was proposed to predict the dynamic deflection of metal plates subjected to underwater shock wave loading.The dynamic response and vibration characteristics of the pressure vessel working subjected to the internal blast loading were studied,through measurement and finite element simulation.The 3D DIC system records full field shape,displacement profiles velocity profiles and strain profiles of the specimen surface.The spectrum distribution was obtained acquired through the spectral analysis,and the small elastic deformation of vessel sheet could be measured.Comparing with the numerical simulation results,the main vibration modes of two kinds of pressure vessel were determined,and the influence of the loading intensity on the vibration characteristics was dicussed.Finally,the DIC results corresponded well with the theoretical natural frequency,indicating the feasibility and reliability of DIC method,and the application field of 3D DIC method are exploited.