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The Mechanics of penetration investigate the interactions between projectiles and targets. The Mechanics of penetration were initially developed with military motives and were used in the design and manufacture of durable military vehicles, warships, protective vests, bulletproof panels, satellite protective equipment, nuclear reactor protection used. In this paper, the penetration of cylindrical and conical-nosed long rods projectiles in normal and the diagonally ceramic target is studied by analytically and numerical methods; And the Interface defeat e phenomenon, in which the projectile is eroded so that the material in the target surface is radial and outward flow. A comparison was also made between the oblique and normal penetration of long rods cylindrical and conical-nosed projectiles, which illustrates the importance of collision angles. The analytical relations related to the reduction of velocity and erosion of the projectile mass were investigated concerning the extraction time and kinetic energy loss of the projectile. Transition from the interface defeat phase to the penetration phase is also described in detail, and the variation of the critical speed suffering from the change in the angle of impact has been investigated. Each of the results of the analytical work and numerical simulations has been evaluated by experimental work carried out in previous studies and the comparison of the results shows the acceptable accuracy for the obtained relationships.

In this paper, the mechanical properties and microstructure of Al6061-graphene oxide (GO) nanocomposites material, produced by stir casting and hot rolling process have been investigated. In order to make composite samples, GO nanoplates with various weight percents of 0.2, 0.5 and 0.8% were added to the molten Al6061 through the stir casting process. Then the cast composite slabs were hot rolled at 530 °C. Tensile and hardness tests were used to study the mechanical properties of nanocomposite specimens. The microstructures of samples were examined by optical and scanning electron microscopes. The scanning electron microscope images and energy dispersive spectroscopy map analyses showed that the GO nanoplates have been uniformly distributed within the Al matrix. The mechanical test results showed considerable improvements in the hardness (by 41%), yield strength (by 43%), tensile strength (by 38%), ductility (by 58%) and toughness (by 116%) of the composite samples with respect to the base alloy. Studying the fracture surface also showed that ductile fracture is the dominant mechanism of fracture in all the specimens.

The anti-armored bullets have more kinetic energy due to additional mass than ordinary bullets which increases their likelihood function of penetration for a different target. It is necessary to seek solutions to reduce the possibility of penetration of this type of bullets. One of the most important parameters influencing penetration is projectile impact velocity. The mechanism of penetration varies in different velocity ranges. In this paper, the phenomenon of buckling steel cone with a nose cone in a collision with ceramic targets was investigated by the explicit finite element method using LS-Dayna software. The numerical simulation shows acceptable accuracy after comparing the results with previous research. In this study, the critical angle of ricochet at a different velocity ranging from 700 m/s to 1000 m/s and optimization of the optimal thickness ratio of ceramic/metal targets has been considered. According to the simulation outputs and analytical relations, it is clear that the critical ricocheting angle has increased with increasing velocity and the probability of projectile penetration is higher. The results also show that in the case of an oblique collision at a certain angle, the projectile velocity decreases with increasing target thickness with no drastic changes in the directional angle. As the angle of oblique increases, the amount of penetration in the target decreases. For long rod projectiles, the reduction in kinetic energy at the same collision velocities is not much different for both vertical and oblique collision modes. The erosion of the projectile mass in oblique collisions is less than in vertical collisions at the same time.

Simulation and analysis of the projectile impact and penetration problem and its effects are among the practical topics that can be used to design bulletproof panel and military equipment, construction of impact and penetration resistant structures, design of projectiles with appropriate penetration strength and High performance noted. One of the most important parameters affecting penetration is the impact velocity of the projectile. The mechanism of penetration varies in different speed ranges. In this paper, Ansys Autodyn software is used for intrusion simulation. The simulation carried out in this study is based on the accuracy and physical conditions of the problem and the compatibility of numerical simulation with the governing analytical relationships indicates the validity and accuracy of the assumptions made in the simulation. In this study, we selected materials such as material behavior, grating, contact surfaces, and controls, as well as collision of the blunt projectile with angles of 0º,15º,30º,45º by of high velocity impact 1000 m/s with the same mass and diameter and shape of the projectile nose and properties. Ceramic materials are discussed. The result of the numerical simulation comparison shows relatively good agreement between them.

The paper deals with composite structures in the field of advanced and modern structures in engineering design and according to high specification of composite materials such as high strength to weight ratio use in various industries such as aerospace, marine. One of the most important fields that Researchers have paid less attention to that is to investigate the effect of stacking sequence on the strength of mechanical joints under impact loading. In view of changing the mechanical properties of composite materials by changing the arrangement of layers, in this study, the effect of different orientation of layers on the strength of pin joints in glass-epoxy composites under low-velocity tensile impact has been investigated. Using the Abaqus software and the finite element method, the impact simulation and the force applied to the mechanical joint were analyzed. To evaluate the simulations, the results of the finite element method have been compared with the experimental results. By observing the results, the introduced finite element model is well-considered and is well-matched with the result of the experimental dataset, which made it a valuable tool for predicting the strength of multi-layer composite materials under impact loadings. Using the results of the model, one can analyze the distribution and type of stress and strain in each layer of composite.

This study attempts to numerically investigate the hydro-thermal characteristics of a ferrofluid (water and 4 vol% Fe 3 O 4 ) in a counter-current horizontal double pipe heat exchanger, which is exposed to a non-uniform transverse magnetic field with different intensities. The magnetic field is generated by an electric current going through a wire located parallel to the inner tube and between two pipes. The single phase model and the control volume technique have been used to study the flow. The effects of magnetic field have been added to momentum equation by applying C++ codes in Ansys Fluent 14. The results show that applying this kind of magnetic field causes kelvin force to be produced perpendicular to the ferrofluid flow, changing axial velocity profile and creating a pair of vortices which leads to an increase in Nusselt number, friction factor and pressure drop. Comparing the enhancement percentage of Nusselt number, friction factor and pressure drop demonstrates that the optimum value of magnetic number for Re ff =50 is between Mn=1.33×10 6 and Mn=2.37×10 6 . So applying non-uniform transverse magnetic field can control the flow of ferrofluid and improve heat transfer process of double pipe heat exchanger.

In this research, the effect of graphene oxide (GO) nanoplates on the microstructure, tensile and perforation behavior of Al6061 matrix has been investigated. The composites with 0.2, 0.5 and 0.8 wt % of GO were fabricated by stir casting and hot rolling process. Optical and scanning electron microscopy observations revealed that the matrix grains are considerably refined by the incorporation of GO nanoplates. The quasi-static tensile tests showed that the grain refinement in the composites gives rise to the accompanied increase in strength and ductility. The penetration tests were carried out using steel flat head projectiles with mass of 4.5 g and initial velocity in range of 100–300 m/s. The experimental as well as the nonlinear simulation results showed that by adding GO nanoplates the ballistic velocity limit of the composite specimens improves by 24% with respect to the base alloy. Also, the energy absorption of composite specimens showed 107% improvement. The experimental data were used to develop an analytical relationship between the weight percent of GO and the deflection of fabricated composites.

In this article a simple penetration model for the terminal ballistic of long rod penetrators is developed. The model is to predict the crater depth of a projectile penetrating into a semi-infinite target. A principle objective was to take an account of strength properties of colliding materials using erosive phenomena. The entire velocity regime from low to hypervelocity is analysed. The effect of the penetrator aspect ratio is also considered in the model. The model developed here is based on the steady-state penetration process and is used to compare with existing experimental measurements. The results of the comparison show very good agreement with experimental investigations of other researchers in this field. The study shows that it is possible to construct a very simple model to predict crater depth for a large range of materials with sufficient accuracy without recourse to high cost of experimentation. In fact, the biggest advantage of this model is simplicity and direct applicability to design process. Historically, penetration mechanics has relied very heavily on experimental investigation. This work gives a quick and easy result with sufficient accuracy which may be useful for many applications. To validate the analytical solution, an experimental method is employed.