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.

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.

Failure Behavior and Numerical Simulation of the Local Damage of Ultra High Strength Fiber Reinforced Concrete Subjected to High Velocity Impact

2014 ◽  
Vol 566 ◽  
pp. 205-210 ◽  
Author(s):  
Seong Bong Cheon ◽  
Masuhiro Beppu ◽  
Yoshimi Sonoda ◽  
Masaharu Itoh
Keyword(s):  
Reinforced Concrete ◽  
High Speed ◽  
High Strength ◽  
Fiber Reinforced Concrete ◽  
Failure Behavior ◽  
Local Damage ◽  
Fiber Reinforced ◽  
Concrete Plates ◽  
High Strength Fiber ◽  
The Impact

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.

Fuel Leaking Analysis of Fuel Tank by Projectiles Impact with Mechanical Properties of Projectiles

2013 ◽  
Vol 644 ◽  
pp. 203-206
Author(s):  
Hai Liang Cai ◽  
Bi Feng Song ◽  
Yang Pei ◽  
Shuai Shi
Keyword(s):  
High Speed ◽  
Drop Size ◽  
Fuel Tank ◽  
Size Distributions ◽  
Sauter Mean Diameter ◽  
Fuel Droplets ◽  
High Speed Impact ◽  
Fuel Tanks ◽  
Rigid Projectile ◽  
Drop Size Distributions

For making sure the dry bay ignition and fire, it’s necessary to calculate the number and the sizes of the droplets and determine the mass flow rate of the fuel induced by high-speed impact and penetration of a rigid projectile into fuel tank. An analytical model is founded and the method for calculating the initial leaking velocity of the fuel is determined. It gives the equation for calculating the drop size distributions of fuel and the Sauter mean diameter (SMD) of droplets, through the Maximum Entropy Theory and the conservation for mass. Using the Harmon’s equation for SMD,the fuel droplets SMD can be calculated. Results shows that the initial leaking velocity of the fuel is about linearly increasing with the velocity of the projectile, the SMD of fuel droplets increases with the hole size of the fuel tank which induced by the penetration of the projectile and linearly decreases with the velocity of the projectile. The results can be used for the ignition and fire analysis of the dry bay adjacent to fuel tanks.

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.

scholarly journals Reduce the Influence of Horizontal and Vertical Cold Joints on the Behavior of High Strength Concrete Beam Casting in Hot Weather by Using Sugar Molasses

2018 ◽  
Vol 7 (4.19) ◽  
pp. 794
Author(s):  
Fatimah Hameed Naser Al-Mamoori ◽  
Ali Hameed Naser Al-Mamoori
Keyword(s):  
High Strength Concrete ◽  
Concrete Beam ◽  
Setting Time ◽  
Weather Condition ◽  
High Strength ◽  
Point Load ◽  
Concrete Element ◽  
Strength Concrete ◽  
Hot Weather ◽  
The Impact

The current research studies the effect of cold joints on the behavior shear and flexure of High Strength Concrete (HSC) beams caused by delayed casting sequence during the hot weather in summer of Iraq.Fresh concrete should be kept alive during the various casting batches for concrete element by re-vibration. However, the over vibration caused loss in homogeneity and it is difficult to keep the workability of concrete during hot weather due to the effect of setting time.To deal with this problem of improper casting sequence, which eventually leads to the formation of cold joints, it will be used sugar waste (named as Sugar Molasses (SM)) is a by-product resulted from refining process of sugar as a delayed agent to increase the setting time in order to prevent early set of concrete due to adverse effects in construction joint of hot weather.In the current study, the first objective aims to investigate some of fresh and hardened mechanical properties of HSC (with high cement content) using SM at percentages of (0, 0.05, 0.1, 0.2, 0.3) % from the weight of cement under the concept of sustainable development. The second objective aims to investigate the location and surface texture effect of horizontal and vertical cold joints on the flexural and shear behavior of beam with/without SM. This objective includes testing of twenty four plain concrete beam of (110×110×650 mm) under two point load; half of them casting without roughing (smooth) the old layer and the other casted after roughed it.SM content of 0.2% of cement weight can improve compressive strength by about 11.2% at 28 days and delay initial setting time by about 4.617 hours (277 minutes). No adverse effect on concrete have been observed at this dosage of SM concentration for the ages of concrete cylinders studied. Delays in the setting of concrete at this dosage of SM content help in reducing the early setting of concrete and therefore reduced the impact of the cold joints formation in concrete beams under Iraqi hot weather condition. The failure load for the beams with SM of smooth and rough vertical joints is in the range between (1.95 - 2.12) and (1.46-1.37); respectively times that of the case of beam without SM. 

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.

scholarly journals Fire Performance of Columns Made of Normal and High Strength Concrete: A Comparative Analysis

2016 ◽  
Vol 711 ◽  
pp. 564-571 ◽  
Author(s):  
Thomas Gernay
Keyword(s):  
Bearing Capacity ◽  
High Strength Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Strength Loss ◽  
Fire Performance ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Strength Concrete ◽  
The Impact

The use of high strength concrete (HSC) in multi-story buildings has become increasingly popular. Selection of HSC over normal strength concrete (NSC) allows for reducing the dimensions of the columns sections. However, this reduction has consequences on the structural performance in case of fire, as smaller cross sections lead to faster temperature increase in the section core. Besides, HSC experiences higher rates of strength loss with temperature and a higher susceptibility to spalling than NSC. The fire performance of a column can thus be affected by selecting HSC over NSC. This research performs a comparison of the fire performance of HSC and NSC columns, based on numerical simulations by finite element method. The thermal and structural analyses of the columns are conducted with the software SAFIR®. The variation of concrete strength with temperature for the different concrete classes is adopted from Eurocode. Different configurations are compared, including columns with the same load bearing capacity and columns with the same cross section. The relative loss of load bearing capacity during the fire is found to be more pronounced for HSC columns than for NSC columns. The impact on fire resistance rating is discussed. These results suggest that consideration of fire loading limits the opportunities for use of HSC, especially when the objective is to reduce the dimensions of the columns sections.

New Approaches for Improved Efficiency and Flexibility in Process Chains of Press Hardening

2015 ◽  
Author(s):  
Dirk Landgrebe ◽  
Julia Schönherr ◽  
Norbert Pierschel ◽  
Stefan Polster ◽  
Andre Mosel ◽  
...  
Keyword(s):  
High Speed ◽  
Technology Development ◽  
Lightweight Design ◽  
High Strength ◽  
Press Hardening ◽  
High Speed Impact ◽  
Contact Heating ◽  
Process Chains ◽  
Impact Cutting ◽  
Significant Research

In the last decade, press hardening has become a fully established technology in both science and industry for the production of ultra-high-strength structural components, especially in the automotive industry. Beside the improvement of car performance such as safety and lightweight design, the production process is also one focus of trends in technology development in the field of press hardening. This paper presents an overview about alternative approaches for optimized process chains of press hardening, also including pre- and post-processing in addition to the actual forming and quenching process. Investigations on direct contact heating technology show new prospects regarding fast and flexible austenitization of blanks at compact device dimensions. By applying high speed impact cutting (HSIC) for trimming of press hardened parts, an alternative technology is available to substitute the slow and energy-intensive laser trimming in today’s press hardening lines. Combined with stroke-to-stroke control based on measuring of process-relevant parameters, a readjustment of the production line is possible in order to produce each part with individual, optimal process parameters to realize zero defect production of property-graded press hardened components with constant high part quality. Significant research in the field of press hardening was carried out at Fraunhofer Institute for Machine Tools and Forming Technology IWU, in the hot forming model process chain which enables the running of experiments under conditions similar to industrial scales. All practical tests were prepared by design of experiments and assisted by thermo-mechanical FE simulations.

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.

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