In this paper, an experimental and numerical study on the inelastic deformation of fully clamped circular, rectangular and triangular plates under the low-velocity hydrodynamic loads has been conducted using the drop-hammer machine. In the experimental section, steel and aluminum plates with three different geometries of circular, rectangular and triangular in different thicknesses of 1 to 3 mm were examined. Experiments were carried out under different levels of energy by changing the height and mass of the hammer and the maximum permanent transverse deflection was recorded as the test output. For better understanding the effect of effective parameters in these experiments, the Design-Expert software was used. In this software, the simultaneous effect of these parameters was investigated using the response surface method. The plate thickness, the standoff distance of the hammer and the mass of hammer were considered as independent quantitative parameters, and the geometry of the plates along with the material of plates was considered as independent qualitative parameters. The obtained regression model has a confidence level of 95% for output prediction. Accordingly, the p-value for the model is less than 0.05, which means that the regression model is significant. The values of R2 and R2adj was 0.9803 and 0.97131, respectively. The results of the regression model have a good agreement with experimental results. In all experiments, the standoff distance of the hammer was the most effective parameter while the mass of the hammer had the least effect on the response. The optimum conditions for each plate were also determined.

One of the main aims of the current study is the experimental investigation and optimization of the dynamic response of polymer-coated aluminum plates under impulsive load. In the experimental study, the effect of several important parameters on the free forming of these structures under gas mixture detonation load, including the effect of aluminum plate thickness and polymeric coating, as well as the effect of applied load on the maximum permanent transverse deflection were investigated. In the optimization section, Design Expert Software was used to investigate the simultaneous effect of the mentioned parameters on the plastic deformation of the structure. In this software, the effect of independent parameters such as metal sheet thickness, polymer-coated thickness and loading impulse on the deflection of the two-layer structure has been investigated using the response surface method. Accordingly, the p-value for the model was less than 0.05, which means that the model is significant. The value of R2 is also equal to 0.9980. The results indicate that the presented model is suitable for these experimental data. The values obtained from the prediction of the model are consistent with the experimental results. Optimal conditions for the minimize deflection of the two-layer structure were also determined and tested experimentally. The result indicates that the prediction of the regression model and experimental data have a good agreement.
 

Manufacturing products using powder compaction is one of the most widely used methods in the industry. In this paper, dynamic compaction of aluminum powder under low-velocity impact loading was investigated using a drop hammer testing machine along with the optimization of effective parameters in this process. In this series of experiments, the green density and green strength of compacted products were measured. The response surface methodology was used to study the influential parameters in the powder compaction process. In this method, the effects of independent parameters including the grain particle size, the hammer mass, and the standoff distance of the hammer on the green density and green strength were evaluated. In the current study, two separate analyses were performed for each output response and the obtained results were summarized in ANOVA tables. The results showed that the p-value for the model is less than 0.05, which means that the model is significant. The values of R² for the green density and green strength are equal to 0.9956 and 0.9912, respectively. The results of the optimization section indicate that the optimum case, the maximum green density as well as green strength at the same time, occurs when the grain particle size, the hammer mass and the standoff distance of the hammer have the maximum values. The factors o standoff distance of hammer and grain particle size have the highest and least effect on responses.
 

Design and safety of natural gas tanks Due to its high use in cars, it is of great importance. Therefore, in this paper, the empirical, numerical and optimization of these reservoirs is investigated. Experimental section designed and manufactured two metal and composite tanks that have been tested for internal pressure and their strength has been determined. Modeling of these tanks has been done in the numerical section with the help of Abaqus software 6.14. In addition to validating the results with experimental data, numerical simulation has been developed. Using the results of the development of numerical simulation and experimental design software, optimization of parameters and their relationship with pressure tolerance in these tanks have been investigated. The numerical and experimental results are in good agreement. Lightweight composite tanks are more resistant to internal pressures, which resulted in a 30% reduction in the weight of composite tanks and a 20% reduction in deformation under operating pressure.

In the present study, the experimental study and regression analysis of the dynamic response of circular plates under uniform and localized blast loading were investigated. To this end, several experiments were performed on steel plates under different conditions in the experimental section. In order to complete the database and perform a comprehensive analysis, fourteen series of experiments and 562 data in the open literature were added to the experimental results of the present study. Subsequently, the effect of the radius and thickness of the plate, the impulse of applied load, the mechanical properties of the plate, the loading radius, and the standoff distance on the maximum deflections of circular plates were simultaneously investigated using the Design-Expert software package and response surface methodology. In order to find a significant model, the confidence level of 95% was considered in the analysis. Two separate analyses were done based on the types of loading. The values of R² for uniform and localized blast loading are equal to 0.9712 and 0.9548, respectively. The results show that the predicted values of the models are in good agreement with the experimental data and the presented models are suitable. Optimal conditions for the minimum deflection of the circular plates under dynamic loading with uniform and local distribution were also presented.

In impact mechanics, layered targets are important due to their high resistance to projectiles penetration. This paper deals with the analytical and numerical analysis of the penetration of tantalum projectiles on semi-infinite ceramic-metal layered targets. In the analytical study, a new modified analytical model based on the analytical model of Fellows is presented. The modifications made to the Fellows analytical model include the changes of velocity of the projectile and ceramic, the angle and timing of the formation of the ceramic cone, the erosion of ceramic, projectile and backing. Each of these modifications alone reduces or increases the depth of penetration, and all of these modifications together improve the depth of penetration. Numerical analysis is done using Abaqus software. The behavior of projectile, ceramic, and aluminum is modeled on the actual behavior of the materials and the deformation. The projectile and backing behavior is modeled with the Johnson-Cook equations and the ceramic behavior with the Drucker-Prager plasticity equation and the state equation of Mie-Gruneisen. The results of the new correction analytical model and numerical simulation are compared with the results of other authors and experimental data. The results show very good agreement. The new modified analytical model, by removing the Fellows model defects, provides a more accurate prediction of the depth of projectile penetration in the ceramic-metal layered targets. So, the weakness of this model, which is related to the unpredictability of penetration depth at low speeds, has been remedied.

One of the main objectives of impact mechanics is the design of a structure resistant to explosion by introducing a structure with a special design pattern while maintaining its lightweight conditions. In this study, the plastic deformation and failure pattern of quadrangular metallic plates under localized impulsive loading were investigated due to the lack of experimental, analytical, and numerical results in the field of deformation of multilayer structures under impulsive loading. In this series of experiments, 26 double-layered metallic plates with different layering arrangements of steel-steel and steel-aluminum in different thicknesses were fabricated and designed. To apply the localized impulsive load, a ballistic pendulum system was used without using standoff distance blast tubes. A thick layer of polyester foam was used to prevent explosive debris. Steel plates in different thicknesses of 1, 2, and 2.5mm, and aluminum plates in different thicknesses of 1 and 2mm in 5 different layering configurations were used. In the experimental study, parameters such as impulse, central permanent deflection, and longitudinal strains in x and y directions were measured. The results showed that the use of aluminum plate as a backing layer reduces the explosive performance of the double-layered mixed configurations of steel-aluminum plates under localized impulsive loading.

In present study, the experimental investigation and regression analysis of the large plastic deformation of square and rectangular plates subjected to extreme dynamic loading with uniform and localized distribution were discussed. In the experimental section, 5 experiments were conducted on mild steel plates with different thicknesses. To perform the regression analysis and multi-objective optimization, Design-Expert software in conjunction with the response surface methodology were exerted. Subsequently, the effect of parameters such as the thickness of the plate, the impulse of applied load, the mechanical properties of the plate, the loading radius, and the ratio of width to length of the plate on the maximum deflection of quadrangular plates was simultaneously investigated. Two separate analyses based on statistical analysis and ANOVA were performed for each type of uniform and localized loading. The values obtained for the coefficient of determination (R²) of two types of uniform and localized loading showed that the models have a good prediction ability of the experimental results and it can be used to evaluate the plastic deformation of the quadrangular plates. Subsequently, the optimal conditions for each effective parameter including yield stress and width to length ratio were determined with respect to considering the minimum values for central deflection and plate thickness simultaneously. The multi-objective optimization results were compared to the experimental results of the present study.

In the last decade, the gas mixture detonation forming (GDF) method has been introduced as a novel and alternative method instead of other high-velocity forming (HVF) methods such as explosive method. Due to the lack of research in this field, the present study investigates the free and die forming of circular metallic plates under gas mixture detonation loading. In this series of experiments, steel plates with thicknesses of 1, 2, and 3mm, aluminum plates with a thickness of 3mm, and brass plates with a thickness of 1mm were used. Furthermore, the test specimens were loaded in the impulse range of 4.12 to 54.68N·s. For better comparison, the same areal density condition was considered to compare the results of steel, aluminum, and brass plates under the same loading conditions. Experimental results showed that using a die with an apex angle of 60° leads to the decrease of the maximum permanent deflection by 14.8, 20.2, and 21.4% in 1, 2, and 3mm steel plates, respectively. Under the same loading and areal density conditions, for free forming, the use of aluminum and brass plates lead to increasing the maximum permanent deflection by 19.4 and 13.1% compared to the steel sample, respectively. However, in die forming, these values were 5 and 2%, respectively. Also, the comparison of the results for aluminum and brass plates shows that the using die forming reduces the maximum permanent deflection of the specimen by 12.1 and 10.6%.