جستجوی مقالات مرتبط با کلیدواژه « penetration depth » در نشریات گروه « مکانیک »

Manipulating and modeling soft objects is a challenging task in the field of robotics. These objects have heavy calculations for modeling due to their infinite degree of freedom. To address this challenge in this paper, we first model soft objects using the mass-spring-damper (MSD) method, which is a good choice to run real-time applications. Then we express the Grasping analysis and introduce challenges such as finding the best position for grasping, contact detection, penetration depth detection to calculate the force applied from the gripper to the object and provide the solution. We also use the Particle swarm optimization (PSO) algorithm to achieve the best performance in the simulation and select the best parameters in this work. Finally, after satisfying the static equilibrium and reducing its error to zero.

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 important components which are used in the shaped charges is liner that its material has a considerable influence on the jet formation and penetration profile. In recent years, researches have focused on the analysis of the effect of bimetallic liners and their effective behavior. In this paper, at the first step, the process of jet formation and the penetration in the steel target is numerically simulated for a shaped charge with copper liner using the Ansys-Autodyn software. Analytical solutions have been done using generalized PER theory for jet formation and hydrodynamics theory for penetration; as well the experimental tests were performed with copper liner. The comparison of penetration profiles obtained from numerical, experimental and analytical methods showed a good agreement. Then, the validated numerical simulations were developed for two single-metal liners of nickel and aluminum, and two bimetallic copper-nickels, and copper-aluminum liners. Also, the results of jet tip velocity, penetration depth and crater diameter have been compared between single and bimetallic liners. Regarding to jet formation and penetration in steel target, the comparison between single and bimetallic liners results shows that the using bimetallic liners, improve crater diameter and depth of penetration simultaneously.

of the main important components which are used in the shaped charges is liner that its material has a considerable influence on the jet formation and penetration profile. In recent years, researches have focused on the analysis of the effect of bimetallic liners and their effective behavior. In this paper, at the first step, the process of jet formation and the penetration in the steel target is numerically simulated for a shaped charge with copper liner using the Ansys-Autodyn software. Analytical solutions have been done using generalized PER theory for jet formation and hydrodynamics theory for penetration; as well the experimental tests were performed with copper liner. The comparison of penetration profiles obtained from numerical, experimental and analytical methods showed a good agreement. Then, the validated numerical simulations were developed for two single-metal liners of nickel and aluminum, and two bimetallic copper-nickels, and copper-aluminum liners. Also, the results of jet tip velocity, penetration depth and crater diameter have been compared between single and bimetallic liners. Regarding to jet formation and penetration in steel target, the comparison between single and bimetallic liners results shows that the using bimetallic liners, improve crater diameter and depth of penetration simultaneously.

In direct injection gaseous fueled engines and during their homogeneous combustion mode, mixture formation is controlled by impinging of fuel jet on piston crown, hence, study of impinging jets can improve development of this type of engines. In the present work, a numerical model for simulating helium impinging jet behavior, injecting in an open environment was conducted by using Ansys Fluent software and validated using existing experimental results. The validated numerical model then was used to study the effects of Pressure ratio, engine rpm and injection timing on methane-air mixture formation in EF7 direct injection engine. Results showed that SST k-ω turbulence model predicts the impinging jet penetration depth much better than k-ε model. Also jet tip penetration would increase with increasing the pressure ratio, but decreases with increasing engine rpm unlike the injection in atmospheric condition. Our study showed that the injection timing can affect the jet penetration, depending on the other engine conditions such as pressure ratio or engine rpm.
In direct injection gaseous fueled engines and during their homogeneous combustion mode, mixture formation is controlled by impinging of fuel jet on piston crown, hence, study of impinging jets can improve development of this type of engines. In the present work, a numerical model for simulating helium impinging jet behavior, injecting in an open environment was conducted by using Ansys Fluent software a

Air entrainment in liquids via a fluid jet, is a complex phenomenon that has important applications in industry and the environment. The impact of a vertical laminar water jet translating over the quiescent pool of water at constant velocity was studied empirically, and the penetration depth as well as distribution of the bubbles formed by this jet was measured for both fresh and sea water with two different optical methods. This experiment was conducted at different flow rates (corresponding to different vertical velocities). In each case, the jet was moved at different horizontal velocities relative to the pool surface. As the jet started its horizontal translation, air began entering the pool from the bottom of the point of impact. Bubbles penetration depth was measured through a high-speed imaging technique, and pulse shadowgraphy was used for measuring the bubbles distribution. Increasing the vertical velocity of the jet while simultaneously decreasing the horizontal velocity of the same led to increased bubble penetration depths, and similar results were obtained for fresh water and sea water. This result was obtained in spite of the fact that the number and size of the bubbles formed in sea water were dramatically different from those formed in fresh water. Moreover, the significant role of buoyant forces in the distribution of the bubbles was obvious. The penetration depth and distribution of the bubbles were measured and reported for various jets with different diameters at different vertical and horizontal velocities.

This paper presents an artificial neural network simulation, based on 216 set of experimental data for prediction of SMAW bead geometry. Input parameters consist of electrode type, current, travel speed, arc length, transverse motion, and angle of the electrode with respect to the vertical plane along the weld line. outputs of the neural network were bead width, bead height, penetration, and the rate of electrode consumption. The Error analysis in the neural network was performed by well-known back-propagation error reduction method containing two hidden layers. The results showed that the results were basically in good agreements with the available experimental data,indicating a suitable technique for simulation of the SMAW. It is concluded that the established neural network system, in conjunction with back-propagation analysis, is able to determine the bead geometry for a set of specified input parameters, facilitating the design of special purpose arc welds.