Papers by Keyword: High Velocity Impact

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Authors: Y. Ichikawa, Kazuhiro Ogawa, M. Nivard, L. Berthe, M. Boustie, M. Ducos, Sophie Barradas, Michel Jeandin
Abstract: MCrAlY-typed coatings are conventional for applications to land-based turbines against hightemperature oxidation and corrosion. However, improvements are still currently expected from innovations in the coating process and/or in the selection of the starting materials. Both types of innovations were studied in the present work. The former consisted in cold spray as a substitute for plasma spray which is conventionally used as the coating process. The latter consisted in developing mechanically-alloyed powders to be suitable for the targeted application especially. In this study, coating-substrate adhesion was considered as the justice of the peace to assess improvements from these innovations. This was determined using the LAser Shock Adhesion Test, namely LASAT, which was recently developed as innovative adhesion testing of thermal spray coatings. Among the main results, mechanical alloying was shown to be satisfactory to result in an homogeneous powder from the mixing of CoNiCrAlY with Mo. This powder could be coldsprayed, all the more easily because of a fine grain size. Results were compared with those obtained from conventional commercial pre-alloyed powders. As a general result, it was shown that cold spray could lead to highly-dense and high-adhesion MCrAlY-typed coatings onto Inconel 625 even though the process is usually claimed to be convenient for high-ductility materials such as copper. Incidentally, LASAT was confirmed to be a flexible and powerful testing tool to study adhesion; which resulted in the ranking of the various types of coatings involved in the work. Results are discussed in the light of an experimental simulation of the impinging of cold-sprayed particles using so-called “laser flier impact experiments”. In this development of this simulation approach to cold spray, the flier was made of a 50μm-thick disc machined from HIP’ed CoNiCrAlY.
Authors: Mohd Rozaiman Aziz, W. Kuntjoro, N.V. David, F. Rais
Abstract: This paper presents the ballistic impact study for the non-filled aluminum tank. The objective was to determine the ballistic limit for front tank wall and rear tank wall. The tank was impacted with fragment simulating projectile (FSP) with various velocities range from 239 m/s up to 556 m/s. The aluminum tank was 3 mm thick, 150 mm wide and 750 mm long. The ends of tank were closed with two Polymethyl methacrylate (PMMA) windows which fixed to the tank with four steel bars. The test was conducted at the Science and Technology Research Institute for Defense (STRIDE) Batu Arang, Selangor. The results showed that the ballistic limit for the front tank wall and rear tank wall was 257.7 m/s and 481 m/s, respectively.
Authors: S. Manigandan
Abstract: The Kevlar is an organic high crystalline fiber belonging to the aromatic polyamide family extensively used for its strength. Kevlar fiber posses high cut resistance and flame resistance, hence they have a wide range of application in ballistic and defense [2]. This paper investigates how K-149 behaves mechanically under sudden high velocity impact, it also shows which types of Kevlar grade hold the maximum impact stiffness capacity. In addition it also predicts the stress induced on the specimen at the time of impact. The ballistic impact object considered as 9mm standard size bullet used in short gun. The assumed velocity for these cases is 650m/s. The specimens K-149 & k-49 taken to be rectangle with the standard size 50 mm x 50 mm. The computational analysis done on Kevlar 49 & 149 and the results have been compared with the help of the pictorial representation of post processing abaqus results and the best ballistic material can be chosen. This paper also provided the recommended research data to fill the technology gap in defense material science.
Authors: J.Y. Kim, In Ok Shim, H.K. Kim, S.S. Hong, Soon Hyung Hong
Abstract: Deformation behaviors under quasi-static and dynamic compression and high velocity impact condition of Ti-6Al-4V ELI (extra low interstitial) alloys in two different conditions were investigated. Mill annealed (MA) alloy, consisted of equiaxed α, and thermomechanically treated (TMT) alloy, consisted of mixed structure of equiaxed α and transformed β, were prepared. Compression tests were performed in low strain rate regime using hydraulic testing machine and were performed in high strain rate regime using split Hopkinson pressure bar. High velocity impact tests were also performed by impacting the test projectiles made of these alloys against a steel target at a velocity of ~400m/s. The compression test results showed that deformation behaviors were influenced by the strain hardening exponent at low strain rate regime, and by both the strain hardening exponent and the strain-rate hardening rate at high strain rate regime. TMT alloy showed higher strength but almost similar fracture strain as MA alloy at a high strain rate of ~6000/s, due to the effect of strain-rate hardening. The high velocity impact test results showed that the projectile of TMT alloy withstood without fracture at higher impact velocity, but the maximum amounts of deformation prior to crack were nearly the same for both alloys. These results were in accord with the results of compression tests at high strain rate regime, that is, higher strength but same fracture strain of TMT alloy compared to MA alloy.
Authors: W.H. Zhu, G. Shi, Shinji Tanimura
Authors: Masuhiro Beppu, Charles Abadie, Jun Takahashi, Atsuhisa Ogawa
Abstract: This study presents the effects of short fiber reinforcement on the local damage of concrete plates subjected to high velocity impact. In a series of tests, three short fiber composite materials were used. Firstly, static bending tests were conducted to reveal mechanical properties in tension of the short fiber reinforced concrete. Then, high velocity impact tests were carried out to examine the effects of short fiber reinforcement on the local damage of concrete plates. Failure mode and strain behavior on the back surface of the short fiber reinforced concrete plates demonstrated that short fiber reinforcement was very effective in reducing the local damage.
Authors: Do Yeon Hwang, Akira Shimamoto, Daiju Numata, Takamase Kikuchi, Kazuyoshi Takayama
Abstract: In this study, dynamic penetration phenomena of high-velocity impact of magnesium alloy were investigated. The surface hardness of magnesium alloy (AZ31B-O) and the heat-treated magnesium alloy (AZ31B-200°C, AZ31B-300°C, and AZ31B-430°C) were examined using Micro Vickers, and the influence of the heat treatment temperature was observed. We analyzed the metal organization using a microscope. We also used a ballistic range (two-stage light gas gun), and the test specimens were set at 0°obliquity at room temperature. A high-speed camera allowed us to capture and analyzed the dynamic penetration phenomena of the test specimen.
Authors: Seong Bong Cheon, Masuhiro Beppu, Yoshimi Sonoda, Masaharu Itoh
Abstract: This study presents the local damage of ultra high strength fiber reinforced concrete plates. Impact test of the reinforced concrete plates using two different short fibers are conducted to examine the failure behavior and impact resistant performance. Material models are discussed and proposed by simulating the high speed tri-compressive and uni-tensile tests. Numerical simulations of the impact tests are carried out. Numerical results show good agreements with the test results.
Authors: Shu Lin Li, Man Yi Hou
Abstract: The finite-element simulation models of the projectile and the discrete rod impacting to the aircraft panel structure in high velocity are established according to some experiment projects. Based on dynamic finite-element Program, the forming of impact damage in the panel structure is simulated. Through comparing the simulation results of damage pattern and size in the panel to the experiment results, the reliability of the material models and equations of state and contact algorithm used in the simulations is testified. Take the simulation of projectile vertically impacting to the panel as example, the aircraft panel structure response characteristics are analyzed briefly based on the results including the displacement of typical node in the panel, the stress course of one element and the energy change of the panel.
Authors: Joel Bell, Yi Xia Zhang, Khin Soe, Phillip Hermes
Abstract: High-velocity impact behaviour of hybrid-fibre engineered cementitious composite (ECC) panels subjected to an impact from a hardened steel, ogive-nosed projectile at velocities between 300-700 m/s is investigated and reported in this paper. The new ECC mix contains a proportion of 0.75% volume high-modulus steel fibres and 1.25% volume low modulus polyvinyl-alcohol (PVA) fibres. The mix is designed to achieve a desired balance between the strain hardening behaviour and impact resistance of material required for impact and blast resistant structures. The new hybrid-fibre ECC demonstrates its excellent capability for impact resistance and strong potential as a protective material with reduced impact damage and distributed micro cracking.
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