Name: blast quantification using hopkinson pressure bars
Uploaded: 2016-07-05T14:00:00.000+00:00
Duration: 9 min 41 s
Description: Watch this Scientific Journal Video about Blast Quantification Using Hopkinson Pressure Bars at JoVE.com

The authors wish to thank the Defence Science and Technology Laboratory for funding the published work.

<ol>
	<li>Esparza, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blast+measurements+and+equivalency+for+spherical+charges+at+small+scaled+distances.">Blast measurements and equivalency for spherical charges at small scaled distances.</a> Int. J. Impact Eng. 4 (1), 23-40 (1986).</li><li>Kingery, C. N., Bulmash, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ARBRL-TR-02555.">ARBRL-TR-02555.</a> Airblast parameters from TNT spherical air burst and hemispherical surface burst. , (1984).</li><li>Hyde, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Conventional weapons program (ConWep). , (1991).</li><li>Randers-Pehrson, G., Bannister, K. 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D., Warren, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Validation+of+semi-empirical+blast+pressure+predictions+for+far+field+explosions+-+is+there+inherent+variability+in+blast+wave+parameters?.">Validation of semi-empirical blast pressure predictions for far field explosions - is there inherent variability in blast wave parameters?.</a> , (2014).</li><li>Rigby, S. E., Tyas, A., Bennett, T., Clarke, S. D., Fay, S. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+negative+phase+of+the+blast+load.">The negative phase of the blast load.</a> Int. J. of Protective Structures. 5 (1), 1-20 (2014).</li><li>Rigby, S. E., Fay, S. D., Tyas, A., Warren, J. A., Clarke, S. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Angle+of+incidence+effects+on+far-field+positive+and+negative+phase+blast+parameters.">Angle of incidence effects on far-field positive and negative phase blast parameters.</a> Int. J. of Protective Structures. 6 (1), 23-42 (2015).</li><li>Tyas, A., Warren, J., Bennett, T., Fay, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prediction+of+clearing+effects+in+far-field+blast+loading+of+finite+targets.">Prediction of clearing effects in far-field blast loading of finite targets.</a> Shock Waves. 21 (2), 111-119 (2011).</li><li>Tyas, A., Watson, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+study+of+the+effect+of+spatial+variation+of+load+in+the+pressure+bar.">A study of the effect of spatial variation of load in the pressure bar.</a> Meas Sci Technol. 11 (11), 1539-1551 (2000).</li><li>Tyas, A., Watson, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+investigation+of+frequency+domain+dispersion+correction+of+pressure+bar+signals.">An investigation of frequency domain dispersion correction of pressure bar signals.</a> Int. J. 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D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Finite+element+simulation+of+plates+under+non-uniform+blast+loads+using+a+point-load+method:+Buried+explosives.">Finite element simulation of plates under non-uniform blast loads using a point-load method: Buried explosives.</a> , (2015).</li><li>Rigby, S. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Finite+element+simulation+of+plates+under+non-uniform+blast+loads+using+a+point-load+method:+Blast+wave+clearing.">Finite element simulation of plates under non-uniform blast loads using a point-load method: Blast wave clearing.</a> , (2015).</li><li>Hallquist, J. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> LS-DYNA theory manual. , (2006).</li><li>Fay, S. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Capturing+the+spatial+and+temporal+variations+in+impulse+from+shallow+buried+charges.">Capturing the spatial and temporal variations in impulse from shallow buried charges.</a> , (2013).</li><li>Fay, S. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+the+spatial+and+temporal+pressure+variation+from+buried+charges.">Measuring the spatial and temporal pressure variation from buried charges.</a> , (2014).</li></ol>

The authors have nothing to disclose.

저자 위에 설명 된 프로토콜을 사용하는 것이 홉 킨슨 압력 바의 배열을 사용하여 폭약에서 매우 다양한 로딩의 높은 정확도 측정치를 얻을 수 있음을 보여 주었다. 이산 감압 시간 이력을 보간 루틴을 사용하는 것이 가능 약술 수치 모델링 또는 모델의 출력을위한 검증 데이터로서로드 함수로서 직접 사용할 수있다 연속 충격 앞쪽으로 변형 될 수있다. 매립 된 전하를 사용?...

폭발물의 출력을 특성화하는 것은 두 (현재 분쟁 지역에서 폭발 장치를 즉석에서 매립형 방어) 군사 및 민간 (구조 구성 요소를 설계), 많은 혜택이 있습니다. 최근에이 주제에 상당한 관심을 받고있다. 수집 된 지식의 대부분은보다 효과적인 보호 구조의 설계를 가능하게 전하의 출력 정량 대상으로하고있다. 여기에 주요 문제는 만든 측정이 높은 충실도의하지 않은 경우 다음이 폭발 사건의 하중 전달의 메커니즘 불분명 남아 있습니다. 이것은 차례로 검증을위한 이러한 측정에 의존하는 수치 모델을 검증하는 문제로 이어집니다. 근접장 용어는 스케일링 거리, Z, 이하 1 ~ M / Z = R / W 1/3, R은 폭발성의 중심으로부터의 거리이다 1/3 kg 미만, W와 폭발을 설명하는 데 사용되는 전하 대량 발현TNT의 등가 질량있다. 이 정권에서로드는 일반적으로 높은 공간 및 시간적으로 비 균일 부하 매우 높은 크기, 특징입니다. 강력한 기기는 이에 근접장 로딩과 관련된 극도의 압력을 측정 할 필요가있다. 스케일 거리 Z에서 &lt;0.4 m는 / 1/3 kg의 폭발 매개 변수를 직접 측정 존재 또는 거의 1이 범위에 대한 반 경험적 예측 데이터가 파라 메트릭 연구에 거의 전적으로 기반 중 하나입니다. 이것은 저자의 의도 된 범위를 벗어나 Kingery 및 Bulmash 2에 의해 주어진 반 경험적 예측을 사용하는 것입니다. 이러한 예측 3,4에 기반 도구가로드의 우수한 일차 추정을 허용하는 동안 그들은 완전히 현재의 연구의 초점이다 근접장 이벤트의 역학을 캡처하지 않습니다. 근거리 폭발 측정이 최근에이은 OUTP을 정량화에 초점을 맞춘매몰 비용에서 유타. 사용 된 방법은 글로벌 임펄스 측정 8-13을 직접 구조 대상 5-7로 인한 변형을 평가 다릅니다. 이러한 방법은 보호 시스템 설계의 검증을위한 유용한 정보를 제공 할 수 있지만 완전히 하중 전달의 메커니즘을 조사 할 수 없습니다. 시험은에 의해 생성되는 등의 매장 깊이를 제어하거나 충격 전면에는 고유의 모양을 보장하지 않습니다 같은 실제적인 이유와 함께, 또는 주변의 풀 스케일 (&gt; 1/4)에 양쪽 실험실 저울 (1/10 풀 스케일)에서 할 수 있습니다 뇌관보다는 베어 요금 (14)의 사용. 매립 전하 토양 조건은 높은 테스트 (15)의 재현성을 보장하기 위해 제어 될 필요가있다. 전하가없는 공기에 배치 또는 매설 여부 독립적 얻어진 폭발 측정에서 가장 근본적인 문제는 계측 deplo 의한 측정의 유효성을 보장하는 것이다YED. 설계된 시험 장치 (16)에 고정 된 &#39;강성&#39;타겟 플레이트는 바의 단부에만 완전히 반영 압력을 기록 할 수 있음을 보장하는 동시에 하다니 홉 킨슨 압력 바 (17) (HPBs)를 보호하기 위해 사용된다. 단단한 목표는 &#39;자유 필드&#39;측정 18-20보다 정확하고 사건보다 반복, 또는이다에서 저자는 이전에 반사 된 압력의 측정을 보여 주었다. 이 판의 형상은 타겟 에지 (21) 주위에 삭제 또는 유동에 의해 생성 된 압력 릴리프 무시할 것이라고 예이다. 이 새로운 시험 장치는 1/4 규모로 건설되고있다. 매장 조건과 폭발물을 통해이 규모 엄격한 제어에서 25mm의 매장 깊이에서 78g으로 축소 5kg의 풀 스케일 충전 크기, 확보 할 수있다.

<table><tbody><tr><td>Load Cell</td><td>RDP</td><td>RSL0960</td><td>This is only indicative, the exact load cell should be able to resolve the required loading</td></tr><tr><td>Steel target plate / HPBs</td><td>Garratts&amp;nbsp;</td><td></td><td>Fabricated to order</td></tr><tr><td>Strain gauge</td><td>Kyowa</td><td>KSP-2-120-E4</td><td>To use with steel HPBs</td></tr><tr><td>Cyanoacrylate</td><td>Kyowa</td><td>CC-33-A</td><td>Check with manufacturer depending on mar material to be used</td></tr><tr><td>Digital Oscilloscope</td><td>TiePie</td><td>HS4 16-bit Handyscopes&amp;nbsp;</td><td>6 used in parallel in current testing</td></tr><tr><td>Leighton Buzzard sand</td><td>Garside sands</td><td>Garside 14/25</td><td>Uniform silica sand&amp;nbsp;</td></tr></tbody></table>

blast quantification using hopkinson pressure bars

그들은 매우 공격적인 환경을 견딜과 메가 파스칼의 수백까지 압력을 측정 할 수 있어야로 근거리 폭발 하중 측정은 여러 센서 유형에 대한 문제를 제시한다. 이 점에서, 홉 킨슨 압력 바의 단순성은 홉 킨슨 바의 측정 끝이 견딜 수 및 가혹한 조건에 노출되는 동안, 스트레인 게이지가 약간의 거리에 부착 할 수있는 막대에 장착한다는 점에서 큰 장점이있다. 이 보호 틀은 스트레인 게이지를 보호하지만, 측정 수집을 방해하지 않은 이용 될 수있다. 압박 막대의 어레이의 사용은 공지 된 이산 지점에서 압력의 시간 이력을 측정 할 수있다. 이 문서는 또한 관심의 평면에 미 계측 위치에서 압력 - 시간 이력을 유도하는 데 사용되는 보간 루틴을 설명합니다. 현재이 기술은 자유 공기 내의 높은 폭발물의 로딩을 측정하기 위해 사용 된 다양한 토양에 얕게 매장.

실효 적 반응 강성 프레임을 제공 할 필요가있다. 현재는 수백 뉴턴 초 총 부과 된 충격 테스트에서 최소 편향에 저항해야합니다. 사용되는 경질 반응 프레임의 그림은 그림 1에 제시되어있다. 각 프레임에서 50mm 스틸 &#39;수용체&#39;판은 크로스 빔의 바닥에 던져되었습니다. 명시 적으로 요구되지 동안,이로드 셀 / 표적 판 쉽게 고정 가능 콘크리트 빔의면에 ?...

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Blast Quantification Using Hopkinson Pressure Bars

This protocol details the use of Hopkinson pressure bars to measure reflected blast loading from near-field explosive events. It is capable of interpolating a pressure-time history at any point on a reflective boundary and as such can be used to fully characterize the spatial and temporal variations in loading produced.

폭발 정량화는 홉 킨슨 압력 막대를 사용하여

Near-field blast load measurement presents an issue to many sensor types as they must endure very aggressive environments and be able to measure pressures ...

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8.9K 조회수.  University of Sheffield. This protocol details the use of Hopkinson pressure bars to measure reflected blast loading from near-field explosive events. It is capable of interpolating a pressure-time history at any point on a reflective boundary and as such can be used to fully characterize the spatial and temporal variations in loading produced.

비디오: Blast Quantification Using Hopkinson Pressure Bars

Impulsive Pressurization of Neuronal Cells for Traumatic Brain Injury Study

A novel impulsive cell pressurization experiment has been developed using a Kolsky bar device to investigate blast-induced traumatic brain injury (TBI). We demonstrate in this video article how blast TBI-relevant impulsive pressurization is applied to the neuronal cells in vitro. This is achieved by using well-controlled pressure pulse created by a specialized Kolsky bar device, with complete pressure history within the cell pressurization chamber recorded. Pressurized neuronal cells are inspected immediately after pressurization, or further incubated to examine the long-term effects of impulsive pressurization on neurite/axonal outgrowth, neuronal gene expression, apoptosis, etc. We observed that impulsive pressurization at about 2 MPa induces distinct neurite loss relative to unpressurized cells. Our technique provides a novel method to investigate the molecular/cellular mechanisms of blast TBI, via impulsive pressurization of brain cells at well-controlled pressure magnitude and duration.

A novel impulsive cell pressurization experiment has been developed using a Kolsky bar device to investigate the molecular/cellular mechanisms of blast-induced traumatic brain injury.

외상성 뇌 손상 연구를위한 Neuronal 셀의 충동 가압

A novel impulsive cell pressurization experiment has been developed using a Kolsky bar device to investigate blast-induced traumatic brain injury (TBI). ...

연구

생체공학

Research and Development of High-performance Explosives

Developmental testing of high explosives for military applications involves small-scale formulation, safety testing, and finally detonation performance tests to verify theoretical calculations. For newly developed formulations, the process begins with small-scale mixes, thermal testing, and impact and friction sensitivity. Only then do subsequent larger scale formulations proceed to detonation testing, which will be covered in this paper. Recent advances in characterization techniques have led to unparalleled precision in the characterization of early-time evolution of detonations. The new technique of Photonic Doppler Velocimetry (PDV) for the measurement of detonation pressure will be shared and compared with traditional fiber-optic detonation velocity and plate-dent calculation of detonation pressure. In particular, the role of aluminum in explosive formulations will be discussed. Recent developments led to the development of explosive formulations that result in reaction of aluminum very early in the detonation product expansion. This enhanced reaction leads to changes in the detonation velocity and pressure due to reaction of the aluminum with oxygen in the expanding gas products.

Developmental testing of high explosives for military applications involves small-scale formulation, safety testing, and finally detonation performance tests to verify theoretical calculations. This paper will share typical development tests associated with the measurement of detonation velocity and detonation pressure.

고성능 폭발물의 연구 개발

Developmental testing of high explosives for military applications involves small-scale formulation, safety testing, and finally detonation performance ...

공학

Quantification of Hydrogen Concentrations in Surface and Interface Layers and Bulk Materials through Depth Profiling with Nuclear Reaction Analysis

Nuclear reaction analysis (NRA) via the resonant 1H(15N,&#945;&#947;)12C reaction is a highly effective method of depth profiling that quantitatively and non-destructively reveals the hydrogen density distribution at surfaces, at interfaces, and in the volume of solid materials with high depth resolution. The technique applies a 15N ion beam of 6.385 MeV provided by an electrostatic accelerator and specifically detects the 1H isotope in depths up to about 2 &#956;m from the target surface. Surface H coverages are measured with a sensitivity in the order of ~1013 cm-2 (~1% of a typical atomic monolayer density) and H volume concentrations with a detection limit of ~1018 cm-3 (~100 at. ppm). The near-surface depth resolution is 2-5 nm for surface-normal 15N ion incidence onto the target and can be enhanced to values below 1 nm for very flat targets by adopting a surface-grazing incidence geometry. The method is versatile and readily applied to any high vacuum compatible homogeneous material with a smooth surface (no pores). Electrically conductive targets usually tolerate the ion beam irradiation with negligible degradation. Hydrogen quantitation and correct depth analysis require knowledge of the elementary composition (besides hydrogen) and mass density of the target material. Especially in combination with ultra-high vacuum methods for in-situ target preparation and characterization, 1H(15N,&#945;&#947;)12C NRA is ideally suited for hydrogen analysis at atomically controlled surfaces and nanostructured interfaces. We exemplarily demonstrate here the application of 15N NRA at the MALT Tandem accelerator facility of the University of Tokyo to (1) quantitatively measure the surface coverage and the bulk concentration of hydrogen in the near-surface region of a H2 exposed Pd(110) single crystal, and (2) to determine the depth location and layer density of hydrogen near the interfaces of thin SiO2 films on Si(100).

We illustrate the application of 1H(15N,&#945;&#947;)12C resonant nuclear reaction analysis (NRA) to quantitatively evaluate the density of hydrogen atoms on the surface, in the volume, and at an interfacial layer of solid materials. The near-surface hydrogen depth profiling of a Pd(110) single crystal and of SiO2/Si(100) stacks is described.

핵 반응 분석과 깊이 프로파일 링을 통해 표면 및 인터페이스 레이어 및 대량 재료의 수소 농도의 정량화

Nuclear reaction analysis (NRA) via the resonant 1H(15N,&#945;&#947;)12C reaction is a highly effective method of depth profiling that quantitatively and ...

A Uniaxial Compression Experiment with CO2-Bearing Coal Using a Visualized and Constant-Volume Gas-Solid Coupling Test System

Injecting carbon dioxide (CO2) into a deep coal seam is of great significance for reducing the concentration of greenhouse gases in the atmosphere and increasing the recovery of coalbed methane. A visualized and constant-volume gas-solid coupling system is introduced here to investigate the influence of CO2 sorption on the physical and mechanical properties of coal. Being able to keep a constant volume and monitor the sample using a camera, this system offers the potential to improve instrument accuracy and analyze fracture evolution with a fractal geometry method. This paper provides all steps to perform a uniaxial compression experiment with a briquette sample in different CO2 pressures with the gas-solid coupling test system. A briquette, cold-pressed by raw coal and sodium humate cement, is loaded in high-pressure CO2, and its surface is monitored in real-time using a camera. However, the similarity between the briquette and the raw coal still needs improvement, and a flammable gas such as methane (CH4) cannot be injected for the test. The results show that CO2 sorption leads to peak strength and elastic modulus reduction of the briquette, and the fracture evolution of the briquette in a failure state indicates fractal characteristics. The strength, elastic modulus, and fractal dimension are all correlated with CO2 pressure but not with a linear correlation. The visualized and constant-volume gas-solid coupling test system can serve as a platform for experimental research about rock mechanics considering the multifield coupling effect.

A Uniaxial Compression Experiment with CO2-Bearing Coal Using a Visualized and Constant-Volume Gas-Solid Coupling Test System

This protocol demonstrates how to prepare a briquette sample and conduct a uniaxial compression experiment with a briquette in different CO2 pressures using a visualized and constant-volume gas-solid coupling test system. It also aims to investigate changes in terms of coal&#8217;s physical and mechanical properties induced by CO2 adsorption.

시각화되고 일정한 부피의가스 고체 커플링 테스트 시스템을 사용하여 CO 2-베어링 석탄을 사용한 축축한 압축 실험

Injecting carbon dioxide (CO2) into a deep coal seam is of great significance for reducing the concentration of greenhouse gases in the atmosphere and ...

환경과학

A Coupled Experiment-finite Element Modeling Methodology for Assessing High Strain Rate Mechanical Response of Soft Biomaterials

This study offers a combined experimental and finite element (FE) simulation approach for examining the mechanical behavior of soft biomaterials (e.g. brain, liver, tendon, fat, etc.) when exposed to high strain rates. This study utilized a Split-Hopkinson Pressure Bar (SHPB) to generate strain rates of 100-1,500 sec-1. The SHPB employed a striker bar consisting of a viscoelastic material (polycarbonate). A sample of the biomaterial was obtained shortly postmortem and prepared for SHPB testing. The specimen was interposed between the incident and transmitted bars, and the pneumatic components of the SHPB were activated to drive the striker bar toward the incident bar. The resulting impact generated a compressive stress wave (i.e. incident wave) that traveled through the incident bar. When the compressive stress wave reached the end of the incident bar, a portion continued forward through the sample and transmitted bar (i.e. transmitted wave) while another portion reversed through the incident bar as a tensile wave (i.e. reflected wave). These waves were measured using strain gages mounted on the incident and transmitted bars. The true stress-strain behavior of the sample was determined from equations based on wave propagation and dynamic force equilibrium. The experimental stress-strain response was three dimensional in nature because the specimen bulged. As such, the hydrostatic stress (first invariant) was used to generate the stress-strain response. In order to extract the uniaxial (one-dimensional) mechanical response of the tissue, an iterative coupled optimization was performed using experimental results and Finite Element Analysis (FEA), which contained an Internal State Variable (ISV) material model used for the tissue. The ISV material model used in the FE simulations of the experimental setup was iteratively calibrated (i.e. optimized) to the experimental data such that the experiment and FEA strain gage values and first invariant of stresses were in good agreement.

The current study prescribes a coupled experiment-finite element simulation methodology to obtain the uniaxial dynamic mechanical response of soft biomaterials (brain, liver, tendon, fat, etc.). The multiaxial experimental results that arose because of specimen bulging obtained from Split-Hopkinson Pressure Bar testing were rendered to a uniaxial true stress-strain behavior when simulated through iterative optimization of the finite element analysis of the biomaterial.

소프트 생체 재료의 높은 변형 속도 기계 응답을 평가하기위한 결합 실험 - 유한 요소 모델링 방법론

This study offers a combined experimental and finite element (FE) simulation approach for examining the mechanical behavior of soft biomaterials (e.g. ...

Conducting Elevated Temperature Normal and Combined Pressure-Shear Plate Impact Experiments Via a Breech-end Sabot Heater System

A novel approach for conducting normal and/or combined pressure-shear plate impact experiments at test temperatures up to 1000 &#176;C is presented. The method enables elevated temperature plate-impact experiments aimed towards probing dynamic behavior of materials under thermomechanical extremes, while mitigating several special experimental challenges faced while performing similar experiments using the conventional plate impact approach. Custom adaptations are made to the breech-end of a single-stage gas-gun at Case Western Reserve University; these adaptations include a precision-machined extension piece made from SAE 4340 steel, which is strategically designed to mate the existing gun-barrel while providing a high tolerance match to the bore and keyway. The extension piece contains a vertical cylindrical heater-well, which houses a heater assembly. A resistive coil heater-head, capable of reaching temperatures of up 1200 &#176;C, is attached to a vertical stem with axial/rotational degrees of freedoms; this enables thin metal specimens held at the front-end of a heat-resistant sabot to be heated uniformly across the diameter to the desired test temperatures. By heating the flyer plate (in this case, the sample) at the breech-end of the gun-barrel instead of at the target-end, several critical experimental challenges can be averted. These include: 1) severe changes in the alignment of the target plate during heating due to the thermal expansion of the several constituents of the target holder assembly; 2) challenges that arise due to the diagnostics elements, (i.e., polymer holographic gratings, and optical probes) being too close to the heated target assembly; 3) challenges that arise for target plates with an optical window, where crucial tolerances between the sample, bond layer, and window become increasingly difficult to maintain at high temperatures; 4) in the case of combined compression-shear plate impact experiments, the need for high-temperature resistant diffraction gratings for the measurement of transverse particle velocity at the free surface of the target; and 5) limitations imposed on the impact velocity necessary for unambiguous interpretation of the measured free surface velocity versus time profile due to thermal softening and possibly yielding of the bounding target plates.By utilizing the adaptations mentioned above, we present results from a series of reverse geometry normal plate impact experiments on commercial purity aluminum at a range of sample temperatures. These experiments show decreasing particle velocities in the impacted state, which are indicative of material softening (decrease in post-yield flow stress) with increasing sample temperatures.

Here, we present a detailed protocol of a new approach for conducting elevated temperature reverse normal plate impact, and combined pressure-and-shear plate impact. The approach involves the use of a breech-end resistive coil heater to heat a sample held at the front-end of a heat-resistant sabot to the desired temperature.

상승 된 온도 정상 고 불 감 증-엔드 송탄 히터 시스템을 통해 압력 전단 플레이트 영향 실험 결합

A novel approach for conducting normal and/or combined pressure-shear plate impact experiments at test temperatures up to 1000 &#176;C is presented. The ...

Use of Atomic Force Microscopy to Measure Mechanical Properties and Turgor Pressure of Plant Cells and Plant Tissues

We present here the use of atomic force microscopy to indent plant tissues and recover its mechanical properties. Using two different microscopes in indentation mode, we show how to measure an elastic modulus and use it to evaluate cell wall mechanical properties. In addition, we also explain how to evaluate turgor pressure. The main advantages of atomic force microscopy are that it is non-invasive, relatively rapid (5~20 min), and that virtually any type of living plant tissue that is superficially flat can be analyzed without the need for treatment. The resolution can be very good, depending on the tip size and on the number of measurements per unit area. One limitation of this method is that it only gives direct access to the superficial cell layer.

Here, we present atomic force microscopy (AFM), operated as a nano- and micro-indentation tool on cells and tissues. The instrument allows the simultaneous acquisition of 3D surface topography of the sample and its mechanical properties, including cell wall Young's modulus as well as turgor pressure.

식물 세포 및 식물 조직의 기계적 특성 및 터거 압력을 측정하기 위해 원자력 현미경 검사법 사용

We present here the use of atomic force microscopy to indent plant tissues and recover its mechanical properties. Using two different microscopes in ...

발생학

A Novel In Vitro Model of Blast Traumatic Brain Injury

Traumatic brain injury is a leading cause of death and disability in military and civilian populations. Blast traumatic brain injury results from the detonation of explosive devices, however, the mechanisms that underlie the brain damage resulting from blast overpressure exposure are not entirely understood and are believed to be unique to this type of brain injury. Preclinical models are crucial tools that contribute to better understand blast-induced brain injury. A novel in vitro blast TBI model was developed using an open-ended shock tube to simulate real-life open-field blast waves modelled by the Friedlander waveform. C57BL/6N mouse organotypic hippocampal slice cultures were exposed to single shock waves and the development of injury was characterized up to 72 h using propidium iodide, a well-established fluorescent marker of cell damage that only penetrates cells with compromised cellular membranes. Propidium iodide fluorescence was significantly higher in the slices exposed to a blast wave when compared with sham slices throughout the duration of the protocol. The brain tissue injury is very reproducible and proportional to the peak overpressure of the shock wave applied.

A Novel In Vitro Model of Blast Traumatic Brain Injury

This paper describes a novel model of primary blast traumatic brain injury. A compressed-air driven shock tube is used to expose in vitro mouse hippocampal slice cultures to a single shock wave. This is a simple and rapid protocol generating a reproducible brain tissue injury with a high throughput.

모델을 새로운 시험관에 폭발 외상 성 뇌 손상의

Traumatic brain injury is a leading cause of death and disability in military and civilian populations. Blast traumatic brain injury results from the ...

신경과학

Low-intensity Blast Wave Model for Preclinical Assessment of Closed-head Mild Traumatic Brain Injury in Rodents

Traumatic brain injury (TBI) is a large-scale public health problem. Mild TBI is the most prevalent form of neurotrauma and accounts for a large number of medical visits in the United States. There are currently no FDA-approved treatments available for TBI. The increased incidence of military-related, blast-induced TBI further accentuates the urgent need for effective TBI treatments. Therefore, new preclinical TBI animal models that recapitulate aspects of human blast-related TBI will greatly advance the research efforts into the neurobiological and pathophysiological processes underlying mild to moderate TBI as well as the development of novel therapeutic strategies for TBI.
Here we present a reliable, reproducible model for the investigation of the molecular, cellular, and behavioral effects of mild to moderate blast-induced TBI. We describe a step-by-step protocol for closed-head, blast-induced mild TBI in rodents using a bench-top setup consisting of a gas-driven shock tube equipped with piezoelectric pressure sensors to ensure consistent test conditions. The benefits of the setup that we have established are its relative low-cost, ease of installation, ease of use and high-throughput capacity. Further advantages of this non-invasive TBI model include the scalability of the blast peak overpressure and the generation of controlled reproducible outcomes. The reproducibility and relevance of this TBI model has been evaluated in a number of downstream applications, including neurobiological, neuropathological, neurophysiological and behavioral analyses, supporting the use of this model for the characterization of processes underlying the etiology of mild to moderate TBI.

We present here a protocol of a blast wave model for rodents to investigate neurobiological and pathophysiological effects of mild to moderate traumatic brain injury. We established a gas-driven, bench-top setup equipped with pressure sensors allowing for reliable and reproducible generation of blast-induced mild to moderate traumatic brain injury.

설치류의 폐쇄 머리 경미한 외상성 뇌 손상의 전임상 평가를위한 저강도 폭발파 모델

Traumatic brain injury (TBI) is a large-scale public health problem. Mild TBI is the most prevalent form of neurotrauma and accounts for a large number of ...

생쥐에서 매우 반복적인 저수준 폭발을 모델링하는 Shocktube 방법

Modeling Highly Repetitive Low-level Blast Exposure in Mice

Exposure to explosive blasts is a significant risk factor for brain trauma among exposed persons. Although the effects of large blasts on the brain are well understood, the effects of smaller blasts such as those that occur during military training are less understood. This small, low-level blast exposure also varies highly according to military occupation and training tempo, with some units experiencing few exposures over the course of several years whereas others experience hundreds within a few weeks. Animal models are an important tool in identifying both the injury mechanisms and long-term clinical health risks following low-level blast exposure. Models capable of recapitulating this wide range of exposures are necessary to inform acute and chronic injury outcomes across these disparate risk profiles.
Although outcomes following a few low-level blast exposures are easily modeled for mechanistic study, chronic exposures that occur over a career may be better modeled by blast injury paradigms with repeated exposures that occur frequently over weeks and months. Shown here are methods for modeling highly repetitive low-level blast exposure in mice. The procedures are based on established and widely used pneumatic shocktube models of open-field blast exposure that can be scaled to adjust the overpressure parameters and the number or interval of the exposures. These methods can then be used to either enable mechanistic investigations or recapitulate the routine blast exposures of clinical groups under study.

저자 스포트라이트: 생쥐에서 낮은 수준의 폭발 노출의 장기 영향 해독

Presented here are methods for producing repeated low-intensity blast exposures using mice.

마우스에서 매우 반복적인 낮은 수준의 폭발 노출 모델링

Exposure to explosive blasts is a significant risk factor for brain trauma among exposed persons. Although the effects of large blasts on the brain are ...