The Effects of Rolling and Annealing on the High Speed Impact Deformation Behavior of Mg-3%Li-1%Nd Alloy

2011 ◽  
Vol 295-297 ◽  
pp. 2261-2266 ◽  
Author(s):  
Teng Liu ◽  
Gui Ying Sha ◽  
He Nan Wang ◽  
Xiao Lei Wang ◽  
Tao Yu ◽  
...  
Keyword(s):  
Microstructure Evolution ◽  
Fracture Mechanism ◽  
Deformation Behavior ◽  
High Speed ◽  
Impact Fracture ◽  
High Speed Impact ◽  
Impact Deformation ◽  
The Impact ◽  
The Relationship

In this paper, the impact deformation behavior of the as-rolled and annealed Mg-3%Li-1%Nd alloy was investigated by using the Hopkinson compressive bar. The effects of rolling and annealing on the high speed impact deformation behavior were analyzed. The relationship between microstructure evolution and impact fracture mechanism was discussed.

The Effects of Rolling and Annealing on the High Speed Impact Deformation Behavior of Mg-3%Li-1%Ce Alloy

2011 ◽  
Vol 415-417 ◽  
pp. 1090-1095
Author(s):  
Teng Liu ◽  
Gui Ying Sha ◽  
He Nan Wang ◽  
Xiao Lei Wang ◽  
Yu Hong Zhu
Keyword(s):  
Strain Rate ◽  
Deformation Behavior ◽  
High Speed ◽  
Static Recrystallization ◽  
Strain Rate Range ◽  
Softening Effect ◽  
Strain Behavior ◽  
High Speed Impact ◽  
Impact Deformation ◽  
The Impact

In this paper, the effects of rolling and annealing on the high speed impact deformation behavior of the Mg-3%Li-1%Ce alloy were investigated by using the Hopkinson compressive bar. The results showed that the microstructures of the as-rolled alloy consisted mainly of deformed grains, with some secondary Mg12Ce particles in grain interior or on grain boundary. After annealing at 350 °C for one hour, static recrystallization happened and grains were significantly refined. For the annealed alloy, the impact stress-strain behavior is non-sensitive to strain rate in the strain rate range of 1000~1750 s-1. Under the strain rate of 2250 s-1, the dynamic behavior demonstrated negative strain rate effect. The occurrence of cracking was supposed to be the main reason for the strain rate softening effect.

Experimental Calibration of ISV Damage Model Constants for Pure Copper for High-Speed Impact Simulation

2016 ◽  
Author(s):  
Yangqing Dou ◽  
Yucheng Liu ◽  
Wilburn Whittington ◽  
Jonathan Miller
Keyword(s):  
High Speed ◽  
Impact Analysis ◽  
Split Hopkinson Pressure Bar ◽  
Internal State ◽  
Pure Copper ◽  
Damage Model ◽  
Hopkinson Pressure Bar ◽  
Experimental Calibration ◽  
High Speed Impact ◽  
The Impact

Coefficients and constants of a microstructure-based internal state variable (ISV) plasticity damage model for pure copper have been calibrated and used for damage modeling and simulation. Experimental stress-strain curves obtained from Cu samples at different strain rate and temperature levels provide a benchmark for the calibration work. Instron quasi-static tester and split-Hopkinson pressure bar are used to obtain low-to-high strain rates. Calibration process and techniques are described in this paper. The calibrated material model is used for high-speed impact analysis to predict the impact properties of Cu. In the numerical impact scenario, a 100 mm by 100 mm Cu plate with a thickness of 10 mm will be penetrated by a 50 mm-long Ni rod with a diameter of 10mm. The thickness of 10 mm was selected for the Cu plate so that the Ni-Cu penetration through the thickness can be well observed through the simulations and the effects of the ductility of Cu on its plasticity deformation during the penetration can be displayed. Also, that thickness had been used by some researchers when investigating penetration mechanics of other materials. Therefore the penetration resistance of Cu can be compared to that of other metallic materials based on the simulation results obtained from this study. Through this study, the efficiency of this ISV model in simulating high-speed impact process is verified. Functions and roles of each of material constant in that model are also demonstrated.

High-speed impacts of slender bodies into non-smooth, complex fluids

2018 ◽  
Vol 861 ◽  
Author(s):  
Ishan Sharma
Keyword(s):  
Penetration Depth ◽  
High Speed ◽  
Complex Fluids ◽  
Laboratory Data ◽  
Impact Speed ◽  
High Speed Impact ◽  
Smooth Complex ◽  
Theoretical Predictions ◽  
Slender Bodies ◽  
The Impact

We present a simple hydrodynamical model for the high-speed impact of slender bodies into frictional geomaterials such as soils and clays. We model these materials as non-smooth, complex fluids. Our model predicts the evolution of the impactor’s speed and the final penetration depth given the initial impact speed, and the material and geometric parameters of the impactor and the impacted material. As an application, we investigate the impact of deep-penetrating anchors into seabeds. Our theoretical predictions are found to match field and laboratory data very well.

scholarly journals Effect of different helmet shell configurations on the protection against head trauma

2019 ◽  
Vol 54 (7-8) ◽  
pp. 408-415 ◽  
Author(s):  
Marta Palomar ◽  
Ricardo Belda ◽  
Eugenio Giner
Keyword(s):  
Head Trauma ◽  
High Speed ◽  
Composite Shell ◽  
Human Head ◽  
High Rate ◽  
Finite Element Models ◽  
High Speed Impact ◽  
Full Metal Jacket ◽  
The Impact ◽  
Single Combat

Head trauma following a ballistic impact in a helmeted head is assessed in this work by means of finite element models. Both the helmet and the head models employed were validated against experimental high-rate impact tests in a previous work. Four different composite ply configurations were tested on the helmet shell, and the energy absorption and the injury outcome resulting from a high-speed impact with full metal jacket bullets were computed. Results reveal that hybrid aramid–polyethylene configurations do not prevent bullet penetration at high velocities, while 16-layer aramid configurations are superior in dissipating the energy absorbed from the impact. The fabric orientation of these laminates proved to be determinant for the injury outcome, as maintaining the same orientations for all the layers led to basilar skull fractures (dangerous), while alternating orientation of the adjacent plies resulted in an undamaged skull. To the authors knowledge, no previous work in the literature has analysed numerically the influence of different stack configurations on a single combat helmet composite shell on human head trauma.

Evaluation of the Impact Formulae for Rigid Projectile Striking on Concrete Target

2011 ◽  
Vol 368-373 ◽  
pp. 894-900 ◽  
Author(s):  
Hao Wu ◽  
Qin Fang
Keyword(s):  
Penetration Depth ◽  
Empirical Formula ◽  
High Strength Concrete ◽  
High Speed ◽  
High Strength ◽  
Local Damage ◽  
High Speed Impact ◽  
Rigid Projectile ◽  
Semi Empirical ◽  
The Impact

Based on the large amounts of field impact tests with different projectile nosed shapes, the abilities of the existing classical empirical and semi-empirical impact formulae in predicting the local damage of normal and high strength concrete targets (NSCT & HSCT) under the strike of rigid projectile were evaluated. It finds that, firstly, for the penetration depth, the Forrestal and Chen & Li semi-empirical formulae, BRL and Whiffen empirical formulae are advised for the NSCT under the impact of ogive nosed projectile; and Chen & Li semi-empirical formula and ACE empirical formulae are advised for the NSCT under the impact of special nosed projectile; the dimensionless penetration depth of NSCT increases linearly with the non-dimensional impact factor. Secondly, for the penetration depth, Chen & Li semi-empirical formula is advised for the HSCT under the mid-to-high speed impact, and the existing formulae are not applicable while the speed of the projectile was relatively low. Thirdly, for the perforation mode of the target, the BRL and Chang empirical formulae are advised for the NSCT, and the Chen semi-empirical formula, ACE and BRL empirical formulae are advised for the HSCT.

Experimental Study on Splashing During Liquid Jet Impingement Onto a Liquid Film

2016 ◽  
Author(s):  
Zhan Yi ◽  
Naoki Oya ◽  
Koji Enoki ◽  
Tomio Okawa ◽  
Shuji Ohno ◽  
...  
Keyword(s):  
Liquid Film ◽  
High Speed ◽  
Nuclear Power ◽  
Jet Impingement ◽  
Liquid Jet ◽  
Jet Engine ◽  
Transition Length ◽  
The Impact ◽  
The Relationship ◽  
Fire Accident

A liquid jet is of considerable importance in many industrial fields including jet cleaning, jet engine and combustion. As an important example, the Monju nuclear power plant in Japan experienced a sodium leak in 1995. This led to a fire accident because the sodium reacted with oxygen in the air. To predict the significance of the fire accident, accurate evaluation of the amount of splashed droplets caused by the sodium jet impingement is of great importance. In this work, the relationship between the condition of a liquid jet and the amount of splashed droplets is explored experimentally. In the experiments, a liquid jet was emanated vertically downward from a circular nozzle onto a liquid film formed on a horizontal plate. Visualization using a high speed camera was performed to observe the condition of the liquid jet. From the nozzle, the mode of the liquid jet changed jet, lump and drop. Here, the jet mode means the continuous jet with smooth surface, the lump mode the continuous jet with disturbed surface and the drop mode the broken jet. Dependences of the transition length to each mode on the important parameters such as the jet velocity and the nozzle diameter were investigated. Measurement was also conducted for the splash ratio that is defined as the ratio of the amount of splashed droplets to the jet flow rate. It was found that the splash ratio is high when the liquid jet is in the drop mode at the impact point. It was shown that the splash ratio can be correlated well as a function of the impact Weber number and the Strouhal number of the droplets impinging the liquid film.

High and Low Speed Impact Characteristics of Nanocomposites

2015 ◽  
Vol 1105 ◽  
pp. 62-66 ◽  
Author(s):  
Saud Aldajah ◽  
Yousef Haik ◽  
Kamal Moustafa ◽  
Ammar Alomari
Keyword(s):  
High Speed ◽  
Impact Resistance ◽  
Absorption Capacity ◽  
Impact Testing ◽  
Energy Absorption Capacity ◽  
Low Speed ◽  
High Speed Impact ◽  
Bulletproof Vest ◽  
Impact Characteristics ◽  
The Impact

Nanocomposites attracted the attention of scientists due to their superior mechanical, thermal, chemical and electrical properties. This research studied the impact of adding carbon nanotubes (CNTs) to the woven Kevlar laminated composites on the high and low speed impact characteristics. Different percentages of CNTs were added to the woven Kevlar-Vinylester composite materials. An in-house developed drop weight testing apparatus was utilized for the low speed impact testing. Two different concentrations of the CNTs were added to a 15-layer woven Kevlar laminates, 0.32 wt% and 0.8 wt%. The results showed that: The 0.32 wt % CNT sample enhanced the interlaminar strength of the composite without enhancing the energy absorption capacity whereas, the 0.8 wt % CNT sample did not improve the impact resistance of the Kevlar composite.For the high speed impact tests, a bulletproof vest was prepared using woven Kevlar, resin, and CNTs at 1.5 w% percentage. The ballistic shooting was carried out by a professional shooter using a 30 caliber and 9 mm bullets for the tests. The CNT bulletproof sample bounced back the 30 caliber copper alloy bullet with no penetration.

Impact Behaviour of Composite Materials by Using Low and High Speed Impact Tests

2012 ◽  
Vol 445 ◽  
pp. 189-194
Author(s):  
Enver Bulent Yalcin ◽  
Volkan Gunay ◽  
Muzeyyen Marsoglu
Keyword(s):  
Composite Materials ◽  
High Speed ◽  
Impact Test ◽  
Woven Fabrics ◽  
Impact Behaviour ◽  
High Speed Impact ◽  
Impact Tests ◽  
Data Acquisition Software ◽  
Damage Process ◽  
The Impact

The study presents the need for instrumented testing to optimizing materials against impact forces. The objective of the study is how the impact behaviour of composite materials is investigated by slow and high speed impact tests. Instron Dynatup 9250HV and Instron Dynatup 8150 Impact test machines (Fig.1.) are used which are located in TUBITAK-MRC, Materials Institute , Impact Test Laboratory". The damage process in composite materials under low and high velocity impact loading and the impact energy-displacement properties of the composite materials were investigated. Composite samples were produced by woven fabrics. The results are given as graphs and tables. The Impulse Data Acquisition software is used to send the data to computer.

A STUDY ON IMPACT DEFORMATION AND TRANSFORMATION BEHAVIOR OF TRIP STEEL BY FINITE ELEMENT SIMULATION AND EXPERIMENT

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5985-5990 ◽  
Author(s):  
TAKESHI IWAMOTO ◽  
TOSHIYUKI SAWA ◽  
MOHAMMED CHERKAOUI
Keyword(s):  
Finite Element ◽  
Martensitic Transformation ◽  
Finite Element Simulation ◽  
Trip Steel ◽  
Deformation Behavior ◽  
Implicit Time ◽  
Transformation Behavior ◽  
Impact Deformation ◽  
Element Simulation ◽  
The Impact

Due to strain-induced martensitic transformation (SIMT), the strength, ductility and toughness of TRIP steel are enhanced. The impact deformation behavior of TRIP steel is very important because it is investigated to apply it for the shock absorption member in automobile industries. However, its behavior is still unclear since it is quite difficult to capture the transformation behavior inside the materials. There are some opinions that the deformation characteristics are not mainly depending on the martensitic transformation due to heat generation by plastic work. Here, the impact compressive deformation behavior of TRIP steel is experimentally studied by Split Hopkinson Pressure Bar (SHPB) method at room temperature. In order to catch SIMT behavior during impact deformation, volume resistivity is measured and a transient temperature is captured by using a quite thin thermocouple. Then, a finite element simulation with the constitutive model for TRIP steel is performed. The finite element equation can be derived from the rate form of principle of virtual work based on the implicit time integration scheme. Finally, the results between the computation and experiment are compared to confirm the validity of computational model.

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