scholarly journals Sacrificial Cladding with Brittle Materials for Blast Protection

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3980
Author(s):  
Ludovic Blanc ◽  
Thérèse Schunck ◽  
Dominique Eckenfels
Keyword(s):  
High Speed ◽  
Granular Media ◽  
Brittle Materials ◽  
Absorption Efficiency ◽  
Point Of View ◽  
Plateau Stress ◽  
Blast Protection ◽  
The Core ◽  
Load Transmission ◽  
Energy Absorption Efficiency

In the following work, sacrificial claddings filled with different brittle materials were investigated, from concrete foam to granular media. They were subjected to blast loading using an explosive driven shock tube, while a sensor measures the load transmission and a high speed camera records the compression of the core. From a macroscopic point of view, concrete foam and granular media can act efficiently as a crushable core but differs greatly in terms of energy dissipation mechanisms. To compare them, granular media was at first treated as a cellular material, and different key parameters (plateau stress, densification strain) were computed using the energy absorption efficiency methodology. The presented tests results, coupled with observation in literature, allow a better understanding on the crushing process of a granular media. In particular, granular media tend to work as a core even for low intensity load, contrary to more classical crushable core.

scholarly journals Дестабилизация внедрения высокоскоростной струи в хрупких материалах

2019 ◽  
Vol 89 (5) ◽  
pp. 685
Author(s):  
Б.В. Румянцев
Keyword(s):  
Brittle Material ◽  
High Speed ◽  
Bending Strength ◽  
Brittle Materials ◽  
Absorption Efficiency ◽  
Hydrodynamic Approximation ◽  
Metal Jet

AbstractThe results of penetration of a high-speed metal jet (with a velocity of 3–7 km/s) into brittle materials (ceramics and glass) have been analyzed. The data on jet destabilization as a result of the response of the brittle material to the high-speed penetration are presented. The generalized dependence of the high-speed jet absorption efficiency on the bending strength of the brittle material has been constructed in the hydrodynamic approximation.

scholarly journals Compressive Properties of A2024 Alloy Foam Fabricated through a Melt Route and a Semi-Solid Route

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 153 ◽  
Author(s):  
Takashi Kuwahara ◽  
Taro Osaka ◽  
Mizuki Saito ◽  
Shinsuke Suzuki
Keyword(s):  
Grain Size ◽  
Absorption Efficiency ◽  
S Phase ◽  
Compressive Properties ◽  
Alloying Element ◽  
Plateau Stress ◽  
Energy Absorption Efficiency ◽  
Semi Solid ◽  
Primary Crystals ◽  
Solid Temperature

A2024 alloy foams were fabricated by two methods. In the first method, the melt was thickened by Mg, which acts as an alloying element (melt route). In the second method, the melt was thickened by using primary crystals at a semi-solid temperature with a solid fraction of 20% (semi-solid route). A2024 alloy foams fabricated through the semi-solid route had coarse and uneven pores. This led to slightly brittle fracture of the foams, which resulted in larger energy absorption efficiency than that of the foams fabricated through the melt route. Moreover, A2024 alloy foams fabricated through the semi-solid route had a coarser grain size because of the coarse primary crystals. However, by preventing the decrease in the alloying element Mg, the θ/θ’ phase was suppressed. Additionally, by preventing the precipitation of the S′ phase, the amount of Guinier-Preston-Bagaryatsky (GPB) zone increased. This resulted in a larger plateau stress.

Energy absorption capability of origami automobile bumper system

2019 ◽  
Vol 233 (18) ◽  
pp. 6577-6587
Author(s):  
Lin Yuan ◽  
Jiayao Ma ◽  
Zhong You
Keyword(s):  
Energy Absorption ◽  
High Speed ◽  
Failure Modes ◽  
Absorption Efficiency ◽  
Vital Role ◽  
Vehicle Safety ◽  
Energy Absorption Efficiency ◽  
Stable Performance ◽  
Absorption Performance ◽  
Bumper System

The crashworthiness of an automobile bumper plays a vital role in overall vehicle safety. Energy absorption efficiency, as well as predictable and stable performance, are the most demanding features in the design of the bumper system. To this end, this paper presents a series of innovative bumper designs using built-in origami patterns. Also, we outline a numerical framework for evaluating the energy absorption performance of a bumper when subjected to an impact loading. Comparative analyses on full frontal and 40% offset frontal impact tests are conducted numerically for both low and high-speed scenarios. It is found that the designed failure modes are successfully triggered and followed during the collision process for the combined origami beam-origami crash box design. Most importantly, this optimal design could absorb 31.5% more energy than the conventional bumper.

Fabrication, Structure and Property of Copper Foam

2018 ◽  
Vol 933 ◽  
pp. 41-48 ◽  
Author(s):  
Chao Qun Guo ◽  
Ya Dong Sun ◽  
Yun Zhou ◽  
Bo Xie ◽  
Tian Yao Wang ◽  
...  
Keyword(s):  
Energy Absorption ◽  
Unit Volume ◽  
Volume Fraction ◽  
Absorption Efficiency ◽  
Plateau Stress ◽  
Structure And Property ◽  
Yield Plateau ◽  
Copper Foam ◽  
Energy Absorption Efficiency ◽  
Absorbing Material

Copper foams by using CaCl2 as space holder were successfully manufactured by sintering and dissolution process. The porosity ranges from 75% to 91%, and cell size from 0.3mm to 3.0m. The volume fraction of CaCl2 and sintering temperature are the main factors that affect porosity of copper foam. The yield plateau stress of copper foams with porosity between 75.88% and 90.19% is in range of 12.1~1.2MPa. The yield plateau stress decreases with the increase of porosity. The energy absorption per unit volume (W) copper foams with porosity between 75.88% and 90.19% is in range of 6.17~0.63MJ/m3. Under the condition of identical porosity, the absorption energy per unit volume (W) of copper foam is about 43% higher than aluminum foam. The maximum ideal energy absorption efficiency of copper foam is about 0.74, it indicates that the copper foam can be used as a good absorbing material.

Comparison of the reluctance laminated and solid rotor synchronous machine operating at high temperatures

2019 ◽  
Vol 38 (4) ◽  
pp. 1111-1119 ◽  
Author(s):  
Marcin Lefik ◽  
Krzysztof Komeza ◽  
Ewa Napieralska-Juszczak ◽  
Daniel Roger ◽  
Piotr Andrzej Napieralski
Keyword(s):  
High Speed ◽  
Design Methodology ◽  
Three Dimensional ◽  
Synchronous Machine ◽  
Point Of View ◽  
Heat Sources ◽  
Model Calculations ◽  
Content Type ◽  
Thermal Phenomenon ◽  
Practical Implications

Purpose The purpose of this paper is to present a comparison between reluctance synchronous machine-enabling work at high internal temperature (HT° machine) with laminated and solid rotor. Design/methodology/approach To obtain heat sources for the thermal model, calculations of the electromagnetic field were made using the Opera 3D program including effect of rotation and the resulting eddy current losses. To analyse the thermal phenomenon, the 3D coupled thermal-fluid (CFD) model is used. Findings The presented results show clearly that laminated construction is much better from a point of view of efficiency and temperature. However, solid construction can be interesting for high speed machines due to their mechanical robustness. Research limitations/implications The main problem, despite the use of parallel calculations, is the long calculation time. Practical implications The obtained simulation and experimental results show the possibility of building a machine operating at a much higher ambient temperature than it was previously produced for example in the vicinity of the aircraft turbines. Originality/value The paper presents the application of fully three-dimensional coupled electromagnetic and thermal analysis of new machine constructions designed for elevated temperature.

Energy Absorption of Origami Crash Box: Numerical Simulation and Theoretical Analysis

2018 ◽  
Author(s):  
Mengyan Shi ◽  
Jiayao Ma ◽  
Yan Chen ◽  
Zhong You
Keyword(s):  
Energy Absorption ◽  
Theoretical Study ◽  
Low Cost ◽  
Deformation Mode ◽  
Absorption Efficiency ◽  
Great Promise ◽  
Good Match ◽  
Energy Absorption Efficiency ◽  
Thin Walled ◽  
Initial Peak

Thin-walled tubes as energy absorption devices are widely in use for their low cost and high manufacturability. Employing origami technique on a tube enables induction of a predetermined failure mode so as to improve its energy absorption efficiency. Here we study the energy absorption of a hexagonal tubular device named the origami crash box numerically and theoretically. Numerical simulations of the quasi-static axial crushing show that the pattern triggers a diamond-shaped mode, leading to a substantial increase in energy absorption and reduction in initial peak force. The effects of geometric parameters on the performance of the origami crash box are also investigated through a parametric study. Furthermore, a theoretical study on the deformation mode and energy absorption of the origami crash box is carried out, and a good match with numerical results is obtained. The origami crash box shows great promise in the design of energy absorption devices.

Bending Behavior of Simply-Supported Sandwich Beams Subjected to Large Deflection

2018 ◽  
Vol 777 ◽  
pp. 569-574
Author(s):  
Zhong You Xie
Keyword(s):  
Energy Absorption ◽  
Large Deflection ◽  
Absorption Efficiency ◽  
Sandwich Beams ◽  
Element Simulation ◽  
Energy Absorption Efficiency ◽  
Load Carrying ◽  
Absorption Performance ◽  
Bending Behavior ◽  
The Moment

Due to thin skins and soft core, it is apt to local indentation inducing the concurrence of geometrical and material nonlinearity in sandwich structures. In the paper, finite element simulation is used to investigate the bending behavior of lightweight sandwich beams under large deflection. A modified formulation for the moment at mid-span section of sandwich beams under large deflection is presented, and energy absorption performance is assessed based on energy absorption efficiency. In addition, it is found that no local indentation arises initially, while later that increases gradually with loading displacement increasing. The height of the mid-span section as well as load-carrying capacity decreases significantly with local indentation depth increasing.

Patriotic Gifts

2018 ◽  
Author(s):  
Thomas Grillot
Keyword(s):  
Family Members ◽  
Point Of View ◽  
Great War ◽  
Historical Anthropology ◽  
Interracial Interactions ◽  
The Core ◽  
The Great War

This chapter looks at these interracial interactions from the point of view of Indians in an effort at writing a historical anthropology of Indian patriotism. At the core of Indians' military participation and commemoration of the Great War, the practice of giving, to non-Indians or to Indians, to outsiders or to insiders, to family members or to complete strangers, structured the expression of patriotism in Indian communities. Examining Memorial and Armistice Days, in particular, this chapter looks at the role these holidays played in allowing Indians to maintain boundaries with their white neighbors and develop a series of adaptations of patriotic symbols and ceremonies that acclimatized patriotism for reservation life on an unprecedented scale.

scholarly journals New Dzungaria Gates for wmlt-corridor: historical necessity

2019 ◽  
Vol 5 (3) ◽  
pp. 36-44
Author(s):  
Viktor A. Bogachev ◽  
Yuri A. Terentyev ◽  
Viktor V. Koledov ◽  
Taras V. Bogachev
Keyword(s):  
Mathematical Models ◽  
Variational Methods ◽  
High Speed ◽  
Optimization Problem ◽  
Point Of View ◽  
The North ◽  
Computer Math ◽  
Pass Through ◽  
Historical Necessity ◽  
North Western

Background: Research is ongoing relating to the analysis of a set of issues that arise in connection with the creation of the operating on the basis of vacuum magnetic technologies a transcontinental high-speed land transport corridor, connecting the eastern regions of China with Russia. As part of the variation calculus task, the geopolitical, economic, social, logistic, geographic, geomorphological, seismological, topographic components of the project are considered, in which it is assumed that the high speed overland route will pass through the north-western part of the historical region of Dzungaria. Aim: Find the most optimal from the point of view of the above components the location of the most important section of high speed overland route passing through Central Asia. Methods: Variational methods for solving an optimization problem with the use of a computer math system. Results: After creating a fairly informative and versatile picture of the region in question, the foundations of the corresponding mathematical models are built. Conclusion: The New Dzungarian Gates is a key element in choosing the location of a high-speed overland route based on VMLT.

Sign in / Sign up

Export Citation Format

Share Document