scholarly journals Nonlinear Material Behavior Analysis under High Compression Pressure in Dynamic Conditions

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Muhammad Zubair Zahid ◽  
Shahid Ikramullah Butt ◽  
Tauqeer Iqbal ◽  
Syed Zohaib Ejaz ◽  
Zhang Faping
Keyword(s):  
High Pressures ◽  
Cost Benefit Analysis ◽  
Nonlinear Behavior ◽  
Cost Benefit ◽  
Piezoelectric Sensor ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Chamber Pressure ◽  
Compression Pressure ◽  
Pressure Transducers

Gun chamber pressure is an important parameter in proofing of ammunition to ensure safety and reliability. It can be measured using copper crushers or piezoelectric sensor. Pressure calculations in copper crusher method are based on linear plastic deformation of copper after firing. However, crusher pressure deformation at high pressures deviates from the corresponding values measured by piezoelectric pressure transducers due to strain rate dependence of copper. The nonlinear deformation rate of copper at high pressure measurements causes actual readings from copper crusher gauge to deviate from true pressure values. Comparative analysis of gun chamber pressure was conducted for 7.62 × 51 mm ammunition using Electronic Pressure, Velocity, and Action Time (EPVAT) system with piezoelectric pressure transducers and conventional crusher gauge. Ammunitions of two different brands were used to measure chamber pressure, namely, NATO standard ammunition and non-NATO standard ammunition. The deformation of copper crushers has also been simulated to compare its deformation with real time firing. The results indicate erratic behavior for chamber pressure by copper crusher as per standard deviation and relative spread and thus prove piezo sensor as more reliable and consistent mode of peak pressure measurement. The results from simulation, cost benefit analysis, and accuracy clearly provide piezo sensors with an edge over conventional, inaccurate, and costly method of copper crusher for ballistic measurements due to its nonlinear behavior.

Simplified phenomenological model of the nonlinear behavior of FRPs under combined stress states

2017 ◽  
Vol 52 (4) ◽  
pp. 475-485 ◽  
Author(s):  
Siegfried Galkin ◽  
Fabian J Schirmaier ◽  
Luise Kärger
Keyword(s):  
Shear Stress ◽  
Phenomenological Model ◽  
Pure Shear ◽  
Nonlinear Behavior ◽  
Strain Curve ◽  
Shear Loading ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Combined Stress ◽  
Stress States

Nonlinear material behavior of FRPs under shear loading is widely observed and investigated. In case of combined stress states under tension and shear, an interaction between the macroscopic shear stress–strain curve evolution and the applied tension has been observed and described by several publications in the past. In the present work, the available experimental data with combined stress states are evaluated and a specific threshold shear stress is found, above which nonlinear material behavior occurs for all stress states. Further, a new simplified phenomenological model is derived to model the nonlinear behavior of FRPs when the threshold shear stress is exceeded. This simplified model only needs the threshold shear stress and one evolution parameter, both derived from a pure shear test, to model nonlinear behavior for all combined stress states. A comparison with the available experimental results and with the predictions of the WWFE-III participants for WWFE-III test case 1 shows a very good agreement.

Analysis of Brazing Stresses in Ceramic-Metal Joints in High-Vacuum Devices

1989 ◽  
Vol 111 (1) ◽  
pp. 21-25 ◽  
Author(s):  
K. L. De Weese ◽  
C. E. Toups ◽  
C. K. H. Dharan
Keyword(s):  
Temperature Dependence ◽  
Material Properties ◽  
High Vacuum ◽  
Nonlinear Behavior ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Metallographic Analysis ◽  
Analysis Model ◽  
Element Analysis ◽  
Sample Test

Significant stresses are induced in brazed metal-to-ceramic joints during cool-down. Analysis of such stresses is complicated by nonlinear material behavior and uncertainties in material properties at and near the braze temperatures. In this study, stresses induced during cool-down from the brazing temperature are analytically determined for a coaxial RF (radio frequency) window, which is an integral component of many traveling-wave tube (TWT) devices. The approach is to use nonlinear finite element analysis which takes into account plastic deformation of the metal components as well as the temperature dependence of material properties. Details of the modeling techniques, analytical assumptions and boundary conditions employed are discussed. In addition, metallographic analysis of the brazed test assemblies is described. Analytically predicted stress distributions showed reasonably good correlation with both the location and direction of cracks observed in the ceramic component of brazed sample test assemblies. The results of this investigation emphasize the need for accurate material properties for the braze alloys used in such joints, including temperature dependence, as well as an understanding of their nonlinear behavior, for the stress analysis model to be accurate. In addition, the important role of joint geometry in the minimization of cool-down stresses in brazed metal-ceramic assemblies is described.

The Use of Cost-Benefit Analysis for Evaluating Efficiency of Public Investment Projects (The Case of Sochi-2014 Winter Olympic Games)

2011 ◽  
pp. 57-78
Author(s):  
I. Pilipenko
Keyword(s):  
Net Present Value ◽  
Olympic Games ◽  
Cost Benefit Analysis ◽  
Public Investment ◽  
Cost Benefit ◽  
Investment Efficiency ◽  
Benefit Analysis ◽  
Step Method ◽  
Investment Projects ◽  
The Usa

The paper analyzes shortcomings of economic impact studies based mainly on input- output models that are often employed in Russia as well as abroad. Using studies about sport events in the USA and Olympic Games that took place during the last 30 years we reveal advantages of the cost-benefit analysis approach in obtaining unbiased assessments of public investments efficiency; the step-by-step method of cost-benefit analysis is presented in the paper as well. We employ the project of Sochi-2014 Winter Olympic and Paralympic Games in Russia to evaluate its efficiency using cost-benefit analysis for five accounts (areas of impact), namely government, households, environment, economic development, and social development, and calculate the net present value of the project taking into account its possible alternatives. In conclusion we suggest several policy directions that would enhance public investment efficiency within the Sochi-2014 Olympics.

Hostile Takeovers and Anti-takeover Defenses in the Russian Corporate Market

2007 ◽  
pp. 70-84 ◽  
Author(s):  
E. Demidova
Keyword(s):  
Cost Benefit Analysis ◽  
Cost Benefit ◽  
Benefit Analysis ◽  
Costs And Benefits ◽  
Hostile Takeovers ◽  
Russian Market ◽  
Takeover Defenses ◽  
The Cost ◽  
European Markets

This article analyzes definitions and the role of hostile takeovers at the Russian and European markets for corporate control. It develops the methodology of assessing the efficiency of anti-takeover defenses adapted to the conditions of the Russian market. The paper uses the cost-benefit analysis, where the costs and benefits of the pre-bid and post-bid defenses are compared.

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