Showing 5 results for Velocity Impact
Dr. Hadi Sabouri, Dr. Gholamhossein Liaghat, Mr. Hamed Ahmadi, Dr. Mojtaba Sadighi,
Volume 8, Issue 4 (1-2014)
Abstract
An experimental study of the high velocity impact on 2/1 GLARE panels has been carried out. Four GLARE 3 panels with (Al/0/90/Al), (Al/02/902/Al), (Al/04/904/Al) and (Al/08/908/Al) configurations were fabricated. All panels had same aluminum thickness. Ballistic tests were conducted using flat ended steel projectiles. The failure modes and energy absorption mechanisms were characterized by observation the front and rear sides and also sectioning the panels. Some global and local failure modes due to high velocity impact were identified. The ballistic limit velocity and energy absorption capacity of each panel set was determined experimentally. Specific perforation energy was applied for comparison the ballistic efficiencies of each target. It was found that the (Al/02/902/Al) sequence has the superior specific perforation energy.
Ehsan Etemadi, Jamal Zamani, M. Vahhab Mousavi, Alesandro Francesconi,
Volume 9, Issue 2 (10-2014)
Abstract
This paper presents a new method to investigate plastic deformation of FCC metals in high strain rates. Experimental set up includes two stages gas gun, spherical projectile and target assembly. Target assembly includes front plate, two pressure bars, FCC specimen, three frames and rigid holder. The set-up is carried out according to the following method: a spherical projectile, accelerated to high velocity with a two-stage gas gun, impacts and penetrates in a front plate attached to the front of input bar and results in propagation of the plane waves in the input and output bars and the specimen (FCC metal). Evaluating of effective parameters such as stress, strain and strain in the specimen rate are conducted by installing strain gauges in the pressure bars. The experimental results are compared with 3D finite element simulation. Also, the effect of projectile velocity, specimen thickness and front plate thickness are investigated. It is concluded that decreasing specimen thickness and appropriate calibration of gas gun to shot projectile to the center of front plate, are appropriate ways to achieve strain rates more than 104 s-1 in the specimen that is difficult to achieve such strain rates in conventional split Hopkinson pressure bar.
Seyedhossein Hosseini, Mohammad Shariyat, Rahmatollah Ghajar,
Volume 10, Issue 2 (11-2015)
Abstract
In the present paper, nonlinear dynamic analysis of low-velocity impact of rectangular composite plates reinforced by SMA strips is investigated. In this regard, effects of the instant phase changes and the local and istatantaneous non-uniform distribution of transformation of the austenite to martensite phases and vice versa is considered, for the first time, implementing a written user defined material subroutine code in the ABAQUS/EXPLICIT finite element analysis code. In contrast to the available models which have used the approximate plate theories, a 3D finite element simulation is utilized for extracting the impact responses based on the elasticity theory. Finally, effects of different parameters such as the in-plane preloads, eccentricity, and indenter energy on the impact responses of the hybrid composite plate are investigated. The simulation results indicate that the SMA can absorb a remarkable portion of the stored impact-induced strain energy due to the superelastic and hysteretic natures of the SMA material, which results in increasing impact strength of the composite plate and decreasing the damage caused due to the impact. Moreover, results show that in the cases of the eccentric impact and presence of the tensile preloads, the contact force increases due to the less movability of the impacted point of the plate a fact that may lead to higher damages.
Seyedhossein Hosseini, Seyed Mohammad Reza Khalili,
Volume 10, Issue 3 (1-2016)
Abstract
In the present paper, three-dimensional numerical analysis of low-velocity impact of rectangular sandwich plates with fiber metal laminate (FML) face sheets is investigated. In contrast to the available models which have used the approximate plate theories, a 3D finite element simulation is utilized for extracting the impact responses based on the elasticity theory. Finally, the effects of different parameters such as fiber type, metal type, indenter energy, eccentricity and the in-plane preloads on the impact responses of the structure are investigated. Numerical results are compared with the experimental data presented in the literature and the numerical model is verified. The simulation results showed that in the cases of the eccentric impact and presence of the tensile preloads, the contact force increases due to the less movability of the impacted point of the plate a fact that may lead to higher damages.
Ali Alavi, Mohammad Solooki,
Volume 19, Issue 2 (8-2024)
Abstract
Sandwich panels are usually widely used in various industries, including aerospace, marine, and automotive industries, due to their strength-to-weight ratio and high energy absorption. . In this paper, the ballistic behavior of sandwich panels with aluminum-polyurea face sheets and aluminum cores in the form of semi-cylindrical waves or with hemispherical holes (single or multi-layer) has been investigated. To increase the ballistic resistance of sandwich panels, the effects of core geometry, core layout, polyurea plates, number of core layers, and projectile impact location at high velocities (50 to 400 m/s) have been simulated A number of 12 different modes were examined in terms of the placement of the face sheets and core layers. The results of the investigation showed that in single-layer cores, by changing the geometry of the core from semi-cylindrical to hemispherical, the ballistic limit velocity has increased by 16%. . In two-layer cores, by shifting the layers with different waves (from semi-cylindrical -hemispherical to hemispherical- semi-cylindrical), the ballistic limit velocity has increased by 4%. The use of polyurea in the sandwich panel increased the ballistic limit velocity by 15%. By increasing the number of semi-cylindrical and hemispherical core layers, the ballistic limit velocity increased by 32 and 29%, respectively. Among the investigated sandwich panels, the values of the ballistic limit and the ratio of expended energy per unit of mass are the best SP2 panel (sandwich panel with aluminum and polyurea face sheets with a thickness of 1 mm and a semi-cylindrical core (double layer) with a thickness of 0.5 mm and radius arc 10 mm) compared to the weakest ones SP5 (sandwich panel with aluminum and polyurea face sheets with a thickness of 1 mm and a hemispherical core with a thickness of 0.5 mm and an arc radius of 20 mm) difference of 92.3% and 254.4% respectively.
