Numerical Review of Jones–Wilkins–Lee Parameters for Trinitrotoluene Explosive in Free-Air Blast

Abstract The analysis of complex blast scenarios typically requires advanced computational methods such as multi-material Eulerian and coupled Eulerian–Lagrangian (CEL) analysis where Jones–Wilkins–Lee (JWL) equation of state is used to model the explosive material. While multiple sets of empirical JWL parameters for trinitrotoluene (TNT) explosives have been published over the past few decades, there is also a lack of guidelines and comparative studies on their applications for the blast analysis. A standardized description of the explosive material behavior allows for a better interpretation of results from research studies involving different blast scenarios and JWL parameters. In this paper, the authors utilize numerical finite element (FE) simulations to investigate the influence of different TNT JWL parameter sets on the blast wave characteristics of a free-air blast across different scaled distances. Utilizing multi-material Eulerian analysis, a series of spherical free-air blasts involving a 100-kg TNT charge modeled with different TNT JWL parameters are conducted. The blast wave characteristics including the incident overpressure, impulse, and time of arrival (TOA) are benchmarked against the empirical-based Kingery–Bulmash air blast formulations through the conventional weapon effect calculator conwep. It was found that the incident overpressure and impulse are highly sensitive to the JWL parameters, with differences as high as 40% at smaller scaled distances, while the influence on TOA is much less significant. This paper hopes to provide a guide for future users on the appropriate JWL parameter sets to model the air blast events involving TNT explosives.

Download Full-text

Material Behavior of 2D Steel Lattices with Different Unit-Cell Patterns

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1046.15 ◽

2021 ◽

Vol 1046 ◽

pp. 15-21

Author(s):

Paiboon Limpitipanich ◽

Pana Suttakul ◽

Yuttana Mona ◽

Thongchai Fongsamootr

Keyword(s):

Elastic Modulus ◽

Experimental Studies ◽

Base Material ◽

Unit Cell ◽

Material Behavior ◽

Closed Form Solutions ◽

The Past ◽

Weight Density ◽

Unit Cells ◽

Cell Patterns

Over the past years, two-dimensional lattices have attracted the attention of several researchers because they are lightweight compared with their full-solid counterparts, which can be used in various engineering applications. Nevertheless, since lattices are manufactured by reducing the base material, their stiffnesses then become lower. This study presents the weight efficiency of the lattices defined by relations between the elastic modulus and the weight density of the lattices. In this study, the mechanical behavior of 2D lattices is described by the in-plane elastic modulus. Experimental studies on the elastic modulus of the 2D lattices made of steel are performed. Three lattices having different unit cells, including square, body-centered, and triangular unit cells, are considered. The elastic modulus of each lattice is investigated by tensile testing. All specimens of the lattices are made of steel and manufactured by waterjet cutting. The experimental results of the elastic modulus of the lattices with the considered unit-cell patterns are validated with those obtained from finite element simulations. The results obtained in this study are also compared with the closed-form solutions founded in the literature. Moreover, the unit-cell pattern yielding the best elastic modulus for the lattice is discussed through weight efficiency.

Download Full-text

Seismic phases and scaling associated with small high-explosive surface shots

Bulletin of the Seismological Society of America ◽

10.1785/bssa0710061731 ◽

1981 ◽

Vol 71 (6) ◽

pp. 1731-1741

Author(s):

I. N. Gupta ◽

R. A. Hartenberger

Keyword(s):

Blast Wave ◽

Rayleigh Waves ◽

Wave Train ◽

Simple Wave ◽

P Wave ◽

Peak Ground Velocity ◽

Air Blast ◽

Geological Conditions ◽

Wide Range ◽

First Arrival

Abstract An analysis of seismic field data from surface shots in two radically different geologic environments shows significantly different seismic phases at the two sites. At the first site, which has a layered sedimentary section, five distinct phases are observed: the P-wave first arrival; a complex wave train consisting of higher mode Rayleigh waves; a precursor to air-blast wave; the air blast wave; and the air-coupled Rayleigh waves. Records from the second site, overlying an unlayered mass of igneous rocks, show only three distinct seismic phases: the P-wave first arrival; a simple wave train of fundamental-mode Rayleigh and Love waves; and an air blast wave. Peak ground velocity, based on the average of the three largest amplitudes in the surface waves preceding the air blast wave, scales well with yield for both sites. Measurements of peak ground velocity may be used to estimate yields of explosive charges at either site within a factor of about 2 if the source distance is known. The scaling relationship appears to be valid over a wide range of yields and site geological conditions.

Download Full-text

THE HORMONAL COMPOSITION OF MILK IN PRODUCTIVE ANIMALS AND ITS SAFETY FOR HUMANS

Problems of Veterinary Sanitation, Hygiene and Ecology ◽

10.36871/vet.san.hyg.ecol.202003005 ◽

2020 ◽

Vol 1 (3) ◽

pp. 313-321

Author(s):

P.A. Popov ◽

◽

V.S. Babunova ◽

Keyword(s):

Trace Elements ◽

Growth Factor ◽

Dairy Products ◽

The Body ◽

The Other ◽

Raw Material ◽

Important Food ◽

The Past ◽

Highly Sensitive ◽

And Control

Hormones are an integral part of milk and throughout lactation, the content of certain hormones is unstable. Hormones regulate the process of starting lactation of animals, the lactation process itself, and also the other functions of the body. Milk is of great importance for the growth of young animals and the formation of immunity. Milk is a special product in the diet and is an important food and raw material for the production of dairy products for people. It contains a large amount of protein, fat, carbohydrates, vitamins and trace elements in biologically available form. But at the same time, over the past few years, more and more evidence has emerged that hormones in dairy products can impact on human health. Thus, some estrogens and insulin-like growth factor IGF-1 are involved in the initiation and provocation of breast, prostate and endometrial tumors. That’s why, it is necessary to normalize and control the content of certain hormones in milk with highly sensitive methods.

Download Full-text

What the past can say about the present and future of fire

Quaternary Research ◽

10.1017/qua.2020.48 ◽

2020 ◽

Vol 96 ◽

pp. 66-87

Author(s):

Jennifer R. Marlon

Keyword(s):

Climate Change ◽

Terrestrial Ecosystems ◽

Combustion Products ◽

Temperature Changes ◽

The Public ◽

The Past ◽

Warming Climate ◽

Highly Sensitive ◽

In Fire ◽

Very High

AbstractWildfires are an integral part of most terrestrial ecosystems. Paleofire records composed of charcoal, soot, and other combustion products deposited in lake and marine sediments, soils, and ice provide a record of the varying importance of fire over time on every continent. This study reviews paleofire research to identify lessons about the nature of fire on Earth and how its past variability is relevant to modern environmental challenges. Four lessons are identified. First, fire is highly sensitive to climate change, and specifically to temperature changes. As long as there is abundant, dry fuel, we can expect that in a warming climate, fires will continue to grow unusually large, severe, and uncontrollable in fire-prone environments. Second, a better understanding of “slow” (interannual to multidecadal) socioecological processes is essential for predicting future wildfire and carbon emissions. Third, current patterns of burning, which are very low in some areas and very high in others—are often unprecedented in the context of the Holocene. Taken together, these insights point to a fourth lesson—that current changes in wildfire dynamics provide an opportunity for paleoecologists to engage the public and help them understand the potential consequences of anthropogenic climate change.

Download Full-text

In silico investigation of biomechanical response of a human subjected to primary blast

10.1101/2021.09.16.460591 ◽

2021 ◽

Author(s):

Sunil Sutar ◽

Shailesh Ganpule

Keyword(s):

White Matter ◽

Blast Wave ◽

Rotational Motion ◽

Blast Waves ◽

Primary Blast ◽

Body Model ◽

The Past ◽

Biomechanical Response ◽

The Brain ◽

Full Body

The response of the brain to the explosion induced primary blast waves is actively sought. Over the past decade, reasonable progress has been made in the fundamental understanding of bTBI using head surrogates and animal models. Yet, the current understanding of how blast waves interact with the human is in nascent stages, primarily due to lack of data in humans. The biomechanical response in human is critically required so that connection to the aforementioned bTBI models can be faithfully established. Here, using a detailed, full-body human model, we elucidate the biomechanical cascade of the brain under a primary blast. The input to the model is incident overpressure as achieved by specifying charge mass and standoff distance through ConWep. The full-body model allows to holistically probe short- (<5 ms) and long-term (200 ms) brain biomechanical responses. The full-body model has been extensively validated against impact loading in the past. In this work, we validate the head model against blast loading. We also incorporate structural anisotropy of the brain white matter. Blast wave human interaction is modeled using a conventional weapon modeling approach. We demonstrate that the blast wave transmission, linear and rotational motion of the head are dominant pathways for the biomechanical loading of the brain, and these loading paradigms generate distinct biomechanical fields within the brain. Blast transmission and linear motion of the head govern the volumetric response, whereas the rotational motion of the head governs the deviatoric response. We also observe that blast induced head rotation alone produces a diffuse injury pattern in white matter fiber tracts. Lastly, we find that the biomechanical response under blast is comparable to the impact event. These insights will augment laboratory and clinical investigations of bTBI and help devise better blast mitigation strategies.

Download Full-text

Pursuing Forecasts of the Behavior and Arrival of Coronal Mass Ejections through Modeling and Observations

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317010882 ◽

2017 ◽

Vol 13 (S335) ◽

pp. 58-64 ◽

Cited By ~ 1

Author(s):

Hebe Cremades

Keyword(s):

Remote Sensing ◽

Coronal Mass Ejections ◽

Empirical Models ◽

Time Of Arrival ◽

Data Sets ◽

Radio Waves ◽

Weather Forecasts ◽

The Past ◽

Increasing Demand ◽

Solar Disturbances

AbstractSophisticated instrumentation dedicated to studying and monitoring our Sun’s activity has proliferated in the past few decades, together with the increasing demand of specialized space weather forecasts that address the needs of commercial and government systems. As a result, theoretical and empirical models and techniques of increasing complexity have been developed, aimed at forecasting the occurrence of solar disturbances, their evolution, and time of arrival to Earth. Here we will review groundbreaking and recent methods to predict the propagation and evolution of coronal mass ejections and their driven shocks. The methods rely on a wealth of data sets provided by ground- and space-based observatories, involving remote-sensing observations of the corona and the heliosphere, as well as detections of radio waves.

Download Full-text