Kevlar is a type of aramid fibers which is characterized by high strength to low weight ratio. This material is widely used in bulletproof vests and helmets, in which it creates a barrier to projectiles to protect specific objectives, laminated tubes and pressure vessels, etc. In this study the ballistic behavior of Kevlar /epoxy composite and Kevlar fabric is investigated. The results showed that Kevlar fabrics were more resistant against projectiles. Tensile and punch tests revealed that although the Kevlar/Epoxy composite enjoys higher strength, undergoes lower deformation than Kevlar fabric. The results also indicated that the failure mechanism of Kevlar fabric was quite ductile whereas the presence of epoxy in Kevlar/epoxy changed the failure mechanism from ductile to brittle in the form of plugging in ballistic tests. Finally, the ballistic behavior of the Kevlar fabric was simulated by ABAQUS finite element software and the results were validated by the experiment.

The ballistic response of the high strength, low alloy (HSLA-100) steel at ambient and temperatures of -400, -800 and -1960°C is investigated in this work. Lambert-jonas equation is used to fit the experimental results into a curve. The effect of quenching on ballistic behavior of HSLA 100 is also studied. The experiments are conducted on 3mm thick rectangular specimens impacted by blunt tip projectiles. The results indicate that for the as-received material, the ballistic limit is nearly the same for ambient and -400°C temperatures, but increases significantly by 30% and 40% for 800 and - 1960°C temperatures, respectively. The same trend is observed for the quenched specimens. However, the increase of ballistic limit is lower for the quenched specimens and is 16% and 30% for -800 and - 1960°C temperatures, respectively. The ballistic test was also simulated using Ls-dyna hydrocode to examine the effect of parameters such as the specimen’s thickness, the projectile’s tip shape and mass on the ballistic limit of the materials.

In this paper, an experimental investigation was conducted to study the ballistic properties of sandwich structures with fiber-metal laminate skins and reinforced syntactic foam core with carbon nanotubes. The syntactic foam was produced using epoxy resin and glass microballoon with volume fractions of 30%, 40%, and 55%. In addition, a series of reinforced samples was created using 40% volume fraction of microballoon and 4% multi-walled carbon nanotubes. The composite fiber-metal laminate skins on each side of the cores were made of one aluminum layer sheet and two layers of glass fiber reinforced polymer composite (GFRP). The structures were subjected to high-velocity impact tests using a gas gun and a conical head projectile. The results were analyzed to determine the effects of microballoon volume fraction and carbon nanotubes reinforced foam on the ballistic behavior of sandwich structures. The experiments showed that increasing microballoon volume fraction up to 40% decreased the projectile residual velocity and increased the ballistic limit velocity and penetration energy. Furthermore, reinforcing syntactic foam with carbon nanotubes significantly affected the ballistic properties of the structure.

This study was designed to investigate the ballistic behavior of ceramic-reinforced aluminum composite plates numerically and experimentally and to present an optimal sample design. The parameters studied were ceramic reinforcement percentage and type of matrix alloy. This study used the matrix alloys 6061, 7075, and 5083. The percentage of ceramics used in this study is 15, 30, and 45% by weight. The samples are in three thicknesses of 20, 25, and 30 mm. 27 simulated samples were numerically analyzed with Abaqus finite element software in this study based on existing ballistic protection criteria, one then determines the optimal numerical sample. Using the squeeze casting method, a laboratory sample has been made and experimentally tested to evaluate the numerical results. Lastly, the numerical analysis and the experimental test were compared and the optimal sample was determined.

The purpose of this paper is to present an analytical model for analyzing the penetration process by aspherical noseshape cylindrical on the kevlar/elastomer and the kevlar/epoxy composites and comparing them with each other using the energy method. To investigate this issue, energy absorptionequations forlinear andnonlinear materials are analyzed as a criterion for the performance of matrix-reinforced fabric. In this predicted model, the dependence of the ballistic behavior of the first and second layers of the composites on each other during the impact is considered. In this presented model, the components of energy absorption include the initial kinetic energy of the projectile, the kinetic energy of the projectile, the kinetic energy of the composite cone ahead of the tip of the projectile, the energies absorbed by primary and secondary yarns, the energies absorbed by the delamination among the layers and the cracking of the matrix, the energy dissipated by plugging of the layers is calculated during impact. The results of this study show a positive effect of elastomer use on thermoset matrix in composite. Also, analytical results are validated with the experimental results of previous studies and the perturbation analysis is done to examine the reason for error.

In this research, the impact behavior of trapezoidal corrugated core sandwich panel reinforced with SMA wires, has been investigated experimentally and numerically. Composite specimens were made to perform tensile, compression and shear tests, and the requisite properties were acquired from the tests. Then, sandwich structures with aluminum corrugated core and 4-layer glass/epoxy composites face-sheets were made using the hand-layup technique. In order to reinforce the composite face-sheets, SMA wires were used in two models: 3 SMA wires without pre strain, 3 SMA wires with 3% pre-strain and 3 SMA wires with 6% pre-strain. The test was performed using a gas gun. To validate and compare the results, the numerical models of the specimens were prepared in LS-Dyna, considering the experimental testing conditions. The results, including ballistic limited velocity and the absorbed energy of the structure were compared and validated by the experimental solutions. The aim of this study was to investigate the effect of adding shape memory alloy wire to reinforce the face-sheets and the effect of pre strain on the ballistic behavior of the sandwich structure. The results shows that presence of the SMA wires and applying pre-strain, leads to increasing energy absorption. Comparing to the wireless sample, the absorbed energy increased about 10%, 22% and 30% in the 3-wires sample without pre-strain, 3-wires sample with 3% pre-strain and 3-wires sample with 6% pre-strain, respectively.

In this paper, a 2D analytical model is introduced for predicting the ballistic behavior of the thin laminated composite plate based on tsai-hill and maximum strain criterions. At first, try to determine the moment deformation along with the expansion of transverse wave from impact point and the nonlinear strains and stresses in the composite plate. Then, the energy absorbed due to failure modes and deflection of composite plate such as elastic deformation energy, longitudinal and lateral fracture energy, kinetic energy of local movement, delamination and matrix cracking energy is calculated. For investigation of the various failed layers is used of tsai-hill and maximum strain criterions. In addition to the effects of strain rate on the mechanical properties of the composite layers is applied momentarily during Penetration process. Finally, the present analytical model based on tsai-hill and maximum strain criterions is compared with experimental results. The maximum strain criterion respect to tsai-hill criterion has shown a good agreement with experimental results in the calculation of ballistic limit velocity. According to the obtained results the share of fracture energy compared to the elastic deformation energy by increasing the thickness becomes more and more. And also, the kinetic energy of the local movement, delamination and matrix cracking energy have lower share in the process of energy absorption.

It is known that friction has a significant effect in determining the ballistic impact performance of woven fabrics. In this paper the ballistic behavior of Twaron Aramid fibers fabrics against high velocity impact of a cylindrical projectile is investigated. Dynamic explicit method using ABAQUS software is utilized to analyze the high-speed impact. For this matter 3D solid elements are used and a VUMAT material model based on maximum stress damage criterion is developed by FORTRAN program. Then using this model, the effects of the friction between yarns on energy absorption of the fabric is investigated. Results indicate that the amount of stress in the fabric is highly sensitive to the friction coefficient between the warp and weft fibers. Increasing the friction between fibers, causes the projectile energy to be distributed among a larger number of threads which increases the penetration time of the projectile in the fibers. In all models, except the case with one layer fabric, higher friction coefficients cause higher energy absorption in the fabric. Moreover, experimental tests were used to validate the model in this project the results have the agreement with the Correlation coeficient determination of 0.94, which verifies the accuracy of the simulation.

It is known that friction has a significant effect on determination of the ballistic impact performance of woven fabrics. In this paper the ballistic behavior of fabrics woven from Twaron and Dyneema Aramid fibers against high velocity impact of a cylindrical projectile is investigated. This paper aims to numerically figure out the effects of inter-yarn friction performance including transverse deformation of fabrics, overall energy absorption and the forms of energy absorption. The numerical results show that increasing inter-yarn friction decreases the transverse deflection abilities of the fabrics and subsequently the response modes of them will transfer from a localized response to a globalized one. With the increase of inter-yarn friction, the energy absorption rate monotonously increases, while the failure time firstly decreases and then increases but further decreases again. Increasing inter-yarn friction also affect the forms of energy absorption. Near zero friction coeficient, strain energy is the dominant failure mechanism of a fabric. With the increase of inter-yarn friction, kinetic energy becomes the dominant failure mechanism. The frictional dissipation energy absorption is maximized for a finite inter-yarn friction. Experimental results were used to validate the results. The predicted values of the model show a good agreement with the experimental data. The correlation coefficient was 0.9426, which verify the accuracy of the simulation.

This paper investigated experimentally and numerically the effect of nanoclay on ballistic impact behavior of GLARE. The prepared GlARE is made of two Aluminum 2024 facing sheets and E glass/ epoxy/nanoclay as nano composite core. Nano composite section has been composed of undirectional E glass 409 g/m2، resin CY 219، hardner HY 5161 and nanoclay closite 30B dispersed into the epoxy system in a 0%، 4%، 7% and 10% ratio in weight with respect to the matrix. All panels fabricated using laid-up method in fiber weight fraction of 60%. Ballistic tests were conducted using Gas gun at the velocity of 205 and 225 m/s. The results of the ballistic impact experiments show that the amount of Specific energy absorption variations in 4% of nanoclay content is insignificant. However، in nanoclay contents of 7% and 10%، the Specific energy absorption increases. In other words، it be concluded that nanoclay has positive effect on higher percentage on the ballistic impact. The 3D finite element (FE) code، LS-DYNA، is used to model and validate the experimentally obtained results. A noticeable correlation was found between experimental and numerical results.