Second Paper: Extrusion of Steel and Titanium

1967 ◽  
Vol 182 (1) ◽  
pp. 188-202 ◽  
Author(s):  
E. R. Austin ◽  
R. Davies ◽  
F. Bakhtar
Keyword(s):  
Impact Velocity ◽  
High Impact ◽  
Velocity Range ◽  
Backward Extrusion ◽  
Forward Extrusion ◽  
High Speeds ◽  
Extruded Product ◽  
Work Of Deformation ◽  
The Impact ◽  
Very High

This paper describes the results of forward and backward extrusion tests on steel and titanium specimens at very high impact speeds, using reductions in area of 44 to 86 per cent. The specimens were in all cases of 1-in diameter, 1.5 in long. For the cold forward extrusion of steel, impact speeds over the range 68-310 ft/s were used. Comparison of mean extrusion and work of deformation at these high speeds was made with the values arising at very low speed. Extrusion pressures were minimal in the impact velocity range 40-80 ft/s. Tests using steel billets preheated to temperatures between 300 and 600°C showed no great advantage in preheating above 400°C. This degree of preheating showed considerable advantages over the cold process, in that extrusion pressures were much reduced, product quality was improved, and higher extrusion ratios could be obtained. Limited backward extrusion tests at 66 ft/s proved the feasibility of the process. Gold forward extrusion of titanium at 65 and 167 ft/s was successful only at the relatively low reductions in area of 44 and 61 per cent. At higher degrees of deformation, the extruded product broke into small pieces.

scholarly journals Cratering for Impact of Hypervelocity Projectiles into Granite Targets within a Velocity Range of 1.91–3.99 km/s: Experiments and Analysis

2020 ◽  
Vol 10 (4) ◽  
pp. 1393
Author(s):  
Xiaofeng Wang ◽  
Jingbo Liu ◽  
Biao Wu ◽  
Defeng Kong ◽  
Jiarong Huang ◽  
...  
Keyword(s):  
Impact Velocity ◽  
Scaling Law ◽  
Density Ratio ◽  
Hypervelocity Impact ◽  
Experimental Results ◽  
Tungsten Alloy ◽  
Regression Equations ◽  
Velocity Range ◽  
Predicted Values ◽  
The Impact

To understand and analyze crater damage of rocks under hypervelocity impact, the hypervelocity impact cratering of 15 shots of hemispherical-nosed cylindrical projectiles into granite targets was studied within the impact velocity range of 1.91–3.99 km/s. The mass of each projectile was 40 g, and the length–diameter ratio was 2. Three types of metal material were adopted for the projectiles, including titanium alloy with a density of 4.44 g/cm3, steel alloy with a density of 7.81 g/cm3, and tungsten alloy with a density of 17.78 g/cm3. The projectile–target density ratio (ρp/ρt) ranged from 1.71 to 6.86. The depth–diameter ratios (H/D) of the craters yielded from the experiments were between 0.14 and 0.24. The effects of ρp/ρt and the impact velocity on the morphologies of the crater were evaluated. According to the experimental results, H/D of craters is negatively correlated with the impact velocity, whereas the correlation between H/D and ρp/ρt is weak positive. The crater parameters were expressed as power law relations of impact parameters by using scaling law analysis. The multiple regression analysis was utilized to obtain the coefficients and the exponents of the relation equations. The predicted values of the regression equations were close to the experimental results.

scholarly journals The impact of errors in medical certification on the accuracy of the underlying cause of death

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0259667
Author(s):  
U. S. H. Gamage ◽  
Tim Adair ◽  
Lene Mikkelsen ◽  
Pasyodun Koralage Buddhika Mahesh ◽  
John Hart ◽  
...  
Keyword(s):  
Cause Of Death ◽  
Death Certificate ◽  
International Classification Of Diseases ◽  
High Impact ◽  
Error Type ◽  
Medical Certification ◽  
Underlying Cause Of Death ◽  
The Impact ◽  
Very High ◽  
Death Data

Background Correct certification of cause of death by physicians (i.e. completing the medical certificate of cause of death or MCCOD) and correct coding according to International Classification of Diseases (ICD) rules are essential to produce quality mortality statistics to inform health policy. Despite clear guidelines, errors in medical certification are common. This study objectively measures the impact of different medical certification errors upon the selection of the underlying cause of death. Methods A sample of 1592 error-free MCCODs were selected from the 2017 United States multiple cause of death data. The ten most common types of errors in completing the MCCOD (according to published studies) were individually simulated on the error-free MCCODs. After each simulation, the MCCODs were coded using Iris automated mortality coding software. Chance-corrected concordance (CCC) was used to measure the impact of certification errors on the underlying cause of death. Weights for each error type and Socio-demographic Index (SDI) group (representing different mortality conditions) were calculated from the CCC and categorised (very high, high, medium and low) to describe their effect on cause of death accuracy. Findings The only very high impact error type was reporting an ill-defined condition as the underlying cause of death. High impact errors were found to be reporting competing causes in Part 1 [of the death certificate] and illegibility, with medium impact errors being reporting underlying cause in Part 2 [of the death certificate], incorrect or absent time intervals and reporting contributory causes in Part 1, and low impact errors comprising multiple causes per line and incorrect sequence. There was only small difference in error importance between SDI groups. Conclusions Reporting an ill-defined condition as the underlying cause of death can seriously affect the coding outcome, while other certification errors were mitigated through the correct application of mortality coding rules. Training of physicians in not reporting ill-defined conditions on the MCCOD and mortality coders in correct coding practices and using Iris should be important components of national strategies to improve cause of death data quality.

scholarly journals Axial Force Coefficient of APFSDS Projectile

2020 ◽  
Vol 1 ◽  
pp. 1-15
Author(s):  
Ammar Trakic
Keyword(s):  
Kinetic Energy ◽  
Impact Velocity ◽  
Axial Force ◽  
High Impact ◽  
Cfd Model ◽  
Force Coefficient ◽  
Terminal Ballistics ◽  
High Impact Velocity ◽  
The World ◽  
The Impact

Armor-piercing ammunition is primarily used to combat against heavy armored targets (tanks), but targets can be light armored vehicles, aircraft, warehouse, structures, etc. It has been shown that the most effective type of anti-tank ammunition in the world is the APFSDS ammunition (Armor Piercing Fin Stabilized Discarding Sabot). The APFSDS projectile flies to the target and with his kinetic energy acts on the target, that is, penetrates through armor and disables the tank and his crew. Since the projectile destroys target with his kinetic energy, then it is necessary for the projectile to have the high impact velocity. The decrease in the velocity of a projectile, during flight, is mainly influenced by aerodynamic forces. The most dominant is the axial force due to the laid trajectory of the projectile. By knowing the axial force (axial force coefficient), it is possible to predict the impact velocity of the projectile, by external ballistic calculation, in function of the distance of the target, and to define the maximum effective range from the aspect of terminal ballistics. In this paper two models will be presented for predicting axial force (the axial force coefficient) of an APFSDS projectile after discarding sabot. The first model is defined in STANAG 4655 Ed.1. This model is used to predict the axial force coefficient for all types of conventional projectiles. The second model for predicting the axial force coefficient of an APFSDS projectile, which is presented in the paper, is the CFD-model (Computed Fluid Dynamics).

Elastic/Plastic Contact Mechanics-Based Analysis of Hard Disk Drive Media Damage From Slider Corner Impacts

2007 ◽  
Author(s):  
Raja R. Katta ◽  
Andreas A. Polycarpou ◽  
Jorge V. Hanchi
Keyword(s):  
Thin Film ◽  
Contact Mechanics ◽  
Impact Damage ◽  
Disk Drive ◽  
High Impact ◽  
Impact Model ◽  
Elastic Plastic ◽  
The Impact ◽  
Contact Parameters ◽  
Very High

A contact mechanics-based elastic-plastic impact model which considers slider corner – head disk interaction has been proposed. This model estimates the impact contact parameters accounting for the plastic deformation effects of the realistic thin-film disk media. These properties were utilized for the elastic-plastic impact model to estimate the contact parameters. Very high impact velocities and/or small slider corner radii resulted is extremely high contact depths where the disk substrate mostly dominated the impact and the effect of layers could not be seen. At lower impact velocities and higher corner radii, the impact damage was relatively smaller. The effect of the thin-film layers, which are stiffer than the substrate, was clearly observed.

Effect of Timing and Velocity of Impact on Ventricular Myocardial Rupture

1983 ◽  
Vol 105 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Ian V. Lau
Keyword(s):  
Impact Velocity ◽  
High Speed ◽  
Left Ventricular ◽  
High Impact ◽  
Muscle Stiffness ◽  
Cardiac Rupture ◽  
Myocardial Wall ◽  
High Impact Velocity ◽  
Myocardial Rupture ◽  
The Impact

The effects of impact timing during the cardiac cycle on the sensitivity of the heart to impact-induced rupture was investigated in an open-chest animal model. Direct mechanical impacts were applied to two adjacent sites on the exposed left ventricular surface at the end of systole or diastole. Impacts at 5 m/s and a contact stroke of 5 cm at the end of systole resulted in no cardiac rupture in seven animals, whereas similar impacts at the end of diastole resulted in six cardiac ruptures. Direct impact at 15 m/s and a contact stroke of 2 cm at the end of either systole or diastole resulted in perforationlike cardiac rupture in all attempts. At low-impact velocity the heart was observed in high-speed movie to bounce away from the impact interface during a systolic impact, but deform around the impactor during a diastolic impact. The heart generally remained motionless during the downward impact stroke at high-impact velocity in either a systolic or diastolic impact. The lower ventricular pressure, reduced muscle stiffness, thinner myocardial wall and larger mass of the filled ventricle probably contributed to a greater sensitivity of the heart to rupture in diastole at low-impact velocity. However, the same factors had no role at high-impact velocity.

First Paper: Extrusion of Aluminium and Copper

1967 ◽  
Vol 182 (1) ◽  
pp. 175-187 ◽  
Author(s):  
E. R. Austin ◽  
R. Davies ◽  
F. Bakhtar
Keyword(s):  
Impact Velocity ◽  
High Speed ◽  
Marked Effect ◽  
Deformation Energy ◽  
Maximum Energy ◽  
Backward Extrusion ◽  
Speed Range ◽  
Limited Series ◽  
Work Of Deformation ◽  
Reduction In Area

This paper describes the results of cold backward extrusion tests on aluminium and copper specimens, using test rigs in which impact velocities up to 300 ft/s could be obtained. The maximum energy available was 10 000 ft lbf, but for the work described here, 6000 ft lbf were adequate for the extrusion of billets of 1-in diameter, 1.5-in long. Comparison was made with extrusion at very low speed, and the effect of impact velocity on extrusion pressure and mean work of deformation assessed. For aluminium, reductions of area of between 44 and 86 per cent were examined. Surprisingly little variation in deformation energy over the speed range was noted, but the optimum impact speed appeared to be in the region of 50-80 ft/s. In the case of copper, where impact speeds up to 240 ft/s were investigated, the optimum impact velocity was about 60 ft/s. A limited series of tests in combined forward and backward extrusion was also carried out in both materials. It was found that both reduction in area and impact velocity had a marked effect on the relative proportions of metal extruded in the two directions. Mention is also made of metallurgical examination into the effect of high-speed working on the properties of extruded metals.

The deformation of solids by liquid impact at supersonic speeds

1961 ◽  
Vol 263 (1315) ◽  
pp. 433-450 ◽  
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Impact Load ◽  
Turbine Blades ◽  
Stress Waves ◽  
Liquid Jet ◽  
High Speeds ◽  
Liquid Impact ◽  
The Impact ◽  
Very High

A study has been made of the deformation of solids at high rates of strain which are produced by the impact of a small cylinder or jet of liquid on the surface of the solid. A method is developed for projecting this jet against the solid at velocities up to 1200 m/s. The subsequent deformation of the solid under impact and the behaviour of the liquid is observed by high-speed photographic methods. The magnitude and duration of the impact load are also measured by using a piezo-electric transducer. The mode of deformation of the solid has been investigated for plastic, elastic and brittle materials. There is evidence that the liquid jet, on impact, behaves initially in a compressible manner. Part of the deformation is due to these compressible effects and part to the shearing action of the liquid flowing at very high speeds across the surface. If the head of the jet has an appropriate shape (e.g. wedge shaped) the velocity of flow across the surface may be much greater than the velocity of approach. It is found that there are five general types of deformation produced in the solid. There are (i) circumferential surface fractures, (ii) subsurface flow and fractures, (iii) large-scale plastic deformation, (iv) shear deformation around the periphery of the impact zone, and (v) fracture due to the reflexion and interference of stress waves. The predominating mode of deformation depends primarily on the mechanical properties of the solid and on the velocity of impact. The observations have a bearing on the practical problem of the erosion of aircraft flying at high speed through rain and on the erosion of turbine blades.

Selection of Densification Strain to Predict Dynamic Crushing Stress at High Impact Velocity of ALPORAS Aluminium Foam

2014 ◽  
Vol 626 ◽  
pp. 383-388 ◽  
Author(s):  
Mohd Azman Yahaya ◽  
Dong Ruan ◽  
Guo Xing Lu ◽  
Matthew S. Dargusch ◽  
Tong Xi Yu
Keyword(s):  
Impact Velocity ◽  
Strain Curve ◽  
High Impact ◽  
Aluminium Foam ◽  
Gas Gun ◽  
High Impact Velocity ◽  
Velocity Prediction ◽  
Blast Loadings ◽  
The Impact ◽  
Dynamic Crushing

Cellular material such as aluminium foam has been considered as a potential material for energy absorption upon impact and blast loadings. One of the most important properties that contribute to this feature is the densification strain. At high impact velocity, prediction of the densification strain from quasi-static engineering stress-strain curve has been found inadequate. Furthermore, theoretical prediction using the equation proposed by Reid et al. always over-predicts the dynamic crushing stress. Formation of the shock wave at high impact velocity is believed to further increase the densification level of the foam. However, this effect is disregarded when determining the densification strain quasi-statically. The present study aims to address this issue by determining the densification strain experimentally from impact tests. Forty cylindrical aluminium foams with three different lengths were used as projectiles and were fired towards a rigid load cell by using a gas gun. The peak forces generated from the impact were recorded and analysed. The experimental densification strains were determined physically by measuring the deformation of the foam projectiles after the tests. It is concluded that, at high impact velocity, the densification strain varies with the initial impact velocity. Therefore an appropriate value of densification strain needs to be used in the equation of dynamic crushing stress for a better approximation.

A discussion on deformation of solids by the impact of liquids, and its relation to rain damage in aircraft and missiles, to blade erosion in steam turbines, and to cavitation erosion - High speed liquid impact

1966 ◽  
Vol 260 (1110) ◽  
pp. 79-85 ◽  
Keyword(s):  
High Speed ◽  
Cavitation Erosion ◽  
High Strain ◽  
Strain Rates ◽  
Steam Turbines ◽  
High Speeds ◽  
Liquid Impact ◽  
Deformation Patterns ◽  
The Impact ◽  
Very High

A study has been made of the deformation at high strain rates of solids under the impact of liquids. A method is described for projecting a short liquid jet against a solid surface at speeds up to 1200 m/s. The flow of the liquid and the deformation of the solid during impact have been examined by high speed photographic methods. An attempt has been made to measure the magnitude and duration of the load by means of a piezoelectric pressure transducer. There is evidence that the liquid behaves initially on impact in a compressible manner. Part of the deformation of the solid is due to this compressible behaviour and part to the erosive shearing action of the liquid flowing at very high speeds out across the surface. The mode of deformation in brittle and in plastically deforming materials has been investigated. The deformation patterns produced are shown to be characteristic of liquid impact. The predominating mechanism of deformation depends on the mechanical properties of the solid and on the velocity of impact.

Fast Clustering Environment Impact using Multi Soft Set Based on Multivariate Distribution

2021 ◽  
Vol 5 (3) ◽  
pp. 291
Author(s):  
Iwan Tri Riyadi Yanto ◽  
Ani Apriani ◽  
Rahmat Hidayat ◽  
Mustafa Mat Deris ◽  
Norhalina Senan
Keyword(s):  
Distribution Function ◽  
Public Perception ◽  
High Impact ◽  
Soft Set ◽  
Multivariate Distribution ◽  
Environment Impact ◽  
Development Activity ◽  
Total Data ◽  
The Impact ◽  
Very High

Every development activity is always related to human or community aspects. This can also lead to changes in the characteristics of the community. The community's increasing awareness and critical attitude need to be accommodated to avoid the emergence of social conflicts in the future. This research is to find out how the public perception about the impact of development on the environment. Two methods are used, i.e., MDA (Maximum Dependency Attribute) and MSMD (the Multi soft set multivariate distribution function). The MDA is to determine the most influential attribute and the Multi soft set multivariate distribution function (MSMD) is to group the selected data into classes with similar characteristics. This will help the police producer plan the right mediation and take quick activity to make strides in the quality of the social environment. The experiment conducted level of impact based on the clustering results with the greatest number of member clusters is cluster 1 (very low impact) with 32.25 % of total data following cluster 5 (Very High impact) with 24.25 % of total data. The experiment obtains the level of impact based on the clustering results. The greatest number of member clusters is cluster 1 (extremely low impact) with 32.25 % of total data following cluster 5 (Very High impact) with 24.25 % of total data. The scatter area impact is spread at districts 6, 7, 10, 11, the most of very high impact and districts 1,2,3,4,5,8 the lowest impact. 

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