Mechanical Response of Future Combat Systems (FCS) High-Energy Gun Propellants at High-Strain Rate

2002 ◽  
Author(s):  
Michael G. Leadore
AIP Advances ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 035145
Author(s):  
Heng-ning Zhang ◽  
Hai Chang ◽  
Jun-qiang Li ◽  
Xiao-jiang Li ◽  
Han Wang

2019 ◽  
Vol 6 (2) ◽  
pp. 40 ◽  
Author(s):  
Raj K. Prabhu ◽  
Mark T. Begonia ◽  
Wilburn R. Whittington ◽  
Michael A. Murphy ◽  
Yuxiong Mao ◽  
...  

Designing protective systems for the human head—and, hence, the brain—requires understanding the brain’s microstructural response to mechanical insults. We present the behavior of wet and dry porcine brain undergoing quasi-static and high strain rate mechanical deformations to unravel the effect of hydration on the brain’s biomechanics. Here, native ‘wet’ brain samples contained ~80% (mass/mass) water content and ‘dry’ brain samples contained ~0% (mass/mass) water content. First, the wet brain incurred a large initial peak stress that was not exhibited by the dry brain. Second, stress levels for the dry brain were greater than the wet brain. Third, the dry brain stress–strain behavior was characteristic of ductile materials with a yield point and work hardening; however, the wet brain showed a typical concave inflection that is often manifested by polymers. Finally, finite element analysis (FEA) of the brain’s high strain rate response for samples with various proportions of water and dry brain showed that water played a major role in the initial hardening trend. Therefore, hydration level plays a key role in brain tissue micromechanics, and the incorporation of this hydration effect on the brain’s mechanical response in simulated injury scenarios or virtual human-centric protective headgear design is essential.


2019 ◽  
Vol 43 (4) ◽  
pp. 684-697 ◽  
Author(s):  
Yuanyuan Zheng ◽  
Lin Zhang ◽  
Qiaoying Shi ◽  
Chengshuang Zhou ◽  
Jinyang Zheng

MRS Advances ◽  
2016 ◽  
Vol 1 (17) ◽  
pp. 1197-1202
Author(s):  
J.A. Brown ◽  
D.M. Bond ◽  
M.A. Zikry

ABSTRACTA dislocation-density based crystalline plasticity, a finite viscoelasticity, and a nonlinear finite-element formulation were used to study the high strain-rate failure of energetic crystalline aggregates. The energetic crystals of RDX (cyclotrimethylene trinitramine) with a polymer binder were subjected to high strain-rate tensile loading, and the predictions indicate that high localized stresses and stress gradients develop due to mismatches along crystalline-crystalline and crystalline-amorphous interfaces. These high-stress interfaces are sites for crack nucleation and propagation, and the predictions are used to show how the cracks nucleate and propagate.


2020 ◽  
Vol 10 (12) ◽  
pp. 4170
Author(s):  
Ahmet Reha Gunay ◽  
Sami Karadeniz ◽  
Mustafa Kaya

Ultra-high-strength concrete is a newly developed construction material that has a minimum 120 MPa or higher compressive strength. Recently, the usage of high-strength and ultra-high-strength concretes has become widespread due to the enhancement of the concrete technology. Many civil engineering structures constructed by using concrete materials are usually subjected to, in addition to static loads, dynamic loads due to earthquakes, wind and storm, impact and blast, which take place under high energy and high strain rate values. The effects of such loadings on the structure must be understood thoroughly. In recent years, the withstanding of a structure on these loading conditions has become a crucial issue for its impact on the economy and human safety. One of the approaches to fulfill these requirements is to develop high-strength or ultra high-strength concretes (UHSCs). In this study, an ultra-high-strength concrete with a compressive strength of 135 MPa was designed and developed. In order to determine the dynamic behavior of this UHSC, the specimens at three height/diameter ratios (approximately, 0.6, 1.0 and 1.2) were extracted from the prepared concrete mixtures. These concrete specimens were tested to determine both the quasi-static and dynamic compressive behaviors of the developed concrete. In the quasi-static compression tests, cylindrical specimens and a conventional compressive testing machine were used. In order to study the dynamic compressive behavior, a Split Hopkinson Pressure Bar (SHPB) test setup was used. In this test system, the time variations of compressive strength, the strain and strain rates under uniaxial pressure loading were experimentally evaluated and the deformation and fracturing processes of the specimens were recorded using a high-speed camera. The test results, based on the testing of 21 different specimens, have shown that the dynamic compressive strength values of the developed concrete varied in the range of 143 to 253 MPa, while the strain rate values varied in the range of 353 s−1 to 1288 s−1. Using the data generated in the SHPB tests, the parameters present in a Johnson–Holmquist–Cook concrete material model, which is used in numerical studies on the high strain rate behavior of concretes, were evaluated.


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