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In this paper, plastic deformation of the clamped mild steel and aluminum circular plates subjected to different hydrodynamic impact loading conditions are investigated. Extensive experimental tests were carried out by using a drop hammer. The experimental results presented in terms of central deflection of the plates, deflection profiles, and strain distributions. The effect of different parameters such as material properties, plate thickness, stand off distance of hammer or the transfer energy were also investigated on behavior of deformation of plate. Analytical modeling was carried out using energy approach and introducing the deflection profile function based on observes result of experimental. In this model effect of strain rate, hoop strain, radius strain and also effects of bending strain energy and membrane strain energy have been inserted. Calculations of the cases indicate that the proposed analytical models are based on reasonable assumptions. So, this method can be used for study of plastic deformation of plates under dynamic loading. The agreement between analytical and experimental results indicates that new analytical approach presented in this work maybe successfully employed for prediction of central deflection in different hydrodynamic impact loading conditions.

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The main aim of this paper is to study the inelastic deformation of fully clamped rectangular plates under hydrodynamic loading by low rate with drop-hammer, both experimentally and analytically. In the analytic section, some models are presented for predicting the mid-point deflection by two methods consisting the plastic hinge and energy method. in the plastic hinge method, it is assumed that the used plate in the experimental analysis consists a central hinge and four decentralized hinge inside and also four hinges for fully clamed supported conditions; but in the energy method, the proposed model assumes the deformation in three directions and membrane and bending strain, besides the deformation profile and also the strain rate is assumed. To do this, in experimental section, some experiments were conducted on rectangular plates with different thickness, materials and different levels of energy in order to validate the obtained results from analytic results and also surveying the mechanical behavior of materials according to impacts. By comparing analytic and experimental results, it is obvious that results have satisfying accuracy, therefore using the presented analytic models is desired for predicting the mid-point deflection of rectangular plates under the hydrodynamic loading.

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The purpose of this paper is to investigate those products which are produced by powder compaction procedure under the low rate impact loading by a drop hammer, both theretically and numerically. Experimental section includes checking the efficiency of density, bending strength and elasticity modulus of the product from grain size and different levels of energy. Two kinds of pure aluminum powder in three different size and also their combination with ceramic are used to obtain this. In the numerical section, dimension analysis method is applied in which non-dimensional models for density, bending strength, and elasticity modulus are presented in form of mathematical functions by means of experimental characteristics and data which are categorized to input and output. The purpose of determination of this model is to reach a reliable and satisfactory prediction for final properties of products subjected to impact loading condition. It is worth to note that singular value decomposition approach is used for calculation of linear coefficients vector which has been obtained by non-dimensional parameters.A comparison between these results and experimental data is done by mathematical functions in order to validate the results. The investigation of training and prediction data errors which has been based on root of mean of squares of error and coefficient of determination shows that the obtained results through mathematical functions have acceptable accuracy; hence utilization of the presented mathematical models for predicting the final properties of product subjected to impact loading is desirable.

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The aim of this paper is to investigate the green density, the percentage of porosity and the density distribution of materials which have been produced by powder compaction procedure under low rate impact loading by using drop hammer both experimentally and analytically. Effect of grain size and different level of energy on density is carried out in the experimental section. In this regard, the effect of different level of energy are investigated by changing mass and height of hammer. The analytical section presents a relation for green density considering a small element of compacting piece and using equilibrium equation, continuity equation and Levy-Mises equation. Using the statistical analysis leads to investigation of the effect of grain size and friction coefficient simultaneously as two impressive factors on analytical green density. In the next step, the percentage of porosity and density distribution was calculated analytically and compared with experimental values. The satisfactory accordance between Experimental results and analytical ones validates the presented analytical results. Also by applying two constant quantities, shape factor and work hardening in analytical relations, the effect of these factors on percentage of porosity and density distribution of products have been investigated.

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In this research, the deformation of circular metal sandwich panels with vertical tube cores under blast load has been investigated numerically and experimentally. The relationship of energy balance in different components of the structure has been considered. The core tubes are installed in a cross arrangement and vertically with the same height between the upper and lower sheets of the sandwich structure. The amount of energy absorbed by the cores is determined according to their location in the structure and the effect of their number and diameter. The grouping of the desired tests for this research has been done according to the thickness of the sheet 1.2 and 2 mm and with aluminum cores with diameters of 12 and 16 (mm). Numerical simulation has been done in the form of free explosion and by defining the pressure function using the Conwep method in Abaqus software. To validate the numerical results, experimental tests have been carried out with the construction of sandwich structure. In both methods, the maximum lateral displacement of the structure at its center and the displacement in terms of distance from the center of the structure, at cores location have been measured. Increased number of tubes in the core of the structure decreased the maximum rise in the upper layer and decreased the transverse displacement of the lower sheet. Structures with fewer cores and less sheet thickness showed more energy absorption. The average difference between the results of numerical and experimental methods was approximately 11%.
 

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In this research, the amount of transverse displacement of circular sandwich panels under explosive loading was investigated using the experimental method, and then, by using the Bessel shape function and subtracting the plastic work of the core components and other deformations from the total kinetic energy given to the structure, the relation for the prediction of the transverse displacement of the plates is provided.The experimental tests are grouped by the construction of the sandwich structure, which is 1.2 and 2mm thick steel plating with aluminum tube cores with external diameters of 12 and 16 mm with a cross arrangement and vertically with the same height between the upper and lower plates of the structure. The results obtained from the methods of this research are expressed by presenting the maximum amount of transverse displacement in terms of the distance from the center of the structure and the amount of length change for each of the cores of the structure. It was found that by increasing the volume of the cores in the sandwich structure, the rigidity of the structure does not necessarily increase against a certain applied load. In the investigation of some structures, the effect of the amount of core collapse on the transverse displacement is almost equal to the effect of the thickness of the plate. The average difference of the results is less than 12 %