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Yanqing Wu

Bio: Yanqing Wu is an academic researcher from Beijing Institute of Technology. The author has contributed to research in topics: Ignition system & Explosive material. The author has an hindex of 9, co-authored 29 publications receiving 212 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, a micro-mechanics model describing hot-spot formation in the energetic crystal powders cyclotetramethylene tetranitramine (HMX) and pentaerythritol tetramitrate (PETN) subjected to drop-weight impact is developed.

43 citations

Journal ArticleDOI
TL;DR: A physical model is developed to describe the viscoelastic-plastic deformation, cracking damage, and ignition behavior of polymer-bonded explosives (PBXs) under mild impact and introduces rate-dependent plasticity into the framework which is more suitable for explosives with relatively high binder content.

37 citations

Journal ArticleDOI
TL;DR: In this article, the thermal-mechanical response of cyclotetramethylene-tetranitramine (HMX) based granular explosives and polymer-bonded explosives (PBXs) under impact loading has been investigated using finite element software ABAQUS.

33 citations

Journal ArticleDOI
TL;DR: A mesoscopic framework is developed to quantify the thermal-mechanical-chemical responses of polymer-bonded explosive (PBX) samples under impact loading and has important implications in understanding hot spot ignition processes and improving predictive capabilities in energetic materials.

29 citations

Journal ArticleDOI
TL;DR: In this article, a damage elasto-viscoplastic model has been developed for cyclotetramethylenetetranitramine (HMX) crystals, which considers the anisotropy nature of HMX crystals and dislocation-mediated plasticity as well as the cleavage damage.

24 citations


Cited by
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01 Jan 2001
TL;DR: In this paper, a model for the axisymmetric growth and coalescence of small internal voids in elastoplastic solids is proposed and assessed using void cell computations.
Abstract: A model for the axisymmetric growth and coalescence of small internal voids in elastoplastic solids is proposed and assessed using void cell computations. Two contributions existing in the literature have been integrated into the enhanced model. The first is the model of Gologanu-Leblond-Devaux, extending the Gurson model to void shape effects. The second is the approach of Thomason for the onset of void coalescence. Each of these has been extended heuristically to account for strain hardening. In addition, a micromechanically-based simple constitutive model for the void coalescence stage is proposed to supplement the criterion for the onset of coalescence. The fully enhanced Gurson model depends on the flow properties of the material and the dimensional ratios of the void-cell representative volume element. Phenomenological parameters such as critical porosities are not employed in the enhanced model. It incorporates the effect of void shape, relative void spacing, strain hardening, and porosity. The effect of the relative void spacing on void coalescence, which has not yet been carefully addressed in the literature. has received special attention. Using cell model computations, accurate predictions through final fracture have been obtained for a wide range of porosity, void spacing, initial void shape, strain hardening, and stress triaxiality. These predictions have been used to assess the enhanced model. (C) 2000 Elsevier Science Ltd. All rights reserved.

519 citations

Journal ArticleDOI
TL;DR: A large number of theoretical methods that have been used to predict their mechanical and spark sensitivity are summarized in this paper, in which the advantages and disadvantages of these methods, together with their scope of use are clarified.
Abstract: Over the past 20 years, a number of scientists have conducted numerous fundamental investigations based on quantum chemistry theory into various mechanistic processes that seems to contribute to the sensitivity of energetic materials. A large number of theoretical methods that have been used to predict their mechanical and spark sensitivity are summarized in this article, in which the advantages and disadvantages of these methods, together with their scope of use are clarified. In addition, the theoretical models for thermal stability of explosives are briefly introduced as a supplement. It has been concluded that the current ability to predict sensitivity is merely based on a series of empirical rules, such as simple oxygen balance, molecular properties, and the ratios of C and H to oxygen for different classes of explosive compounds. These are valid only for organic classes of explosives, though some special models have been proposed for inorganic explosives, such as azides. An exact standard for sensitivity should be established experimentally by some new techniques for both energetic compounds and their mixtures. © 2013 Wiley Periodicals, Inc.

109 citations

Journal ArticleDOI
TL;DR: In this article, a criterion for the ignition of granular explosives and polymer-bonded explosives under shock and non-shock loading is developed based on integration of a quantification of the distributions of the sizes and locations of hotspots in loading events.
Abstract: A criterion for the ignition of granular explosives (GXs) and polymer-bonded explosives (PBXs) under shock and non-shock loading is developed. The formulation is based on integration of a quantification of the distributions of the sizes and locations of hotspots in loading events using a cohesive finite element method (CFEM) developed recently and the characterization by Tarver et al. [C. M. Tarver et al., "Critical conditions for impact- and shock-induced hot spots in solid explosives," J. Phys. Chem. 100, 5794–5799 (1996)] of the critical size-temperature threshold of hotspots required for chemical ignition of solid explosives. The criterion, along with the CFEM capability to quantify the thermal-mechanical behavior of GXs and PBXs, allows the critical impact velocity for ignition, time to ignition, and critical input energy at ignition to be determined as functions of material composition, microstructure, and loading conditions. The applicability of the relation between the critical input energy (E) an...

87 citations

Journal ArticleDOI
TL;DR: In this article, high speed synchrotron X-ray experiments are conducted to visualize the in situ deformation and the fracture mechanisms in polymer bonded explosives (PBXs), which are composed of octahydro-1,3,5,7-tetranitro- 1, 3, 5,7tetrazocine (HMX) crystals and hydroxylterminated polybutadiene binder doped with iron (III) oxide.
Abstract: Fracture of crystals and frictional heating are associated with the formation of “hot spots” (localized heating) in energetic composites such as polymer bonded explosives (PBXs). Traditional high speed optical imaging methods cannot be used to study the dynamic sub-surface deformation and the fracture behavior of such materials due to their opaque nature. In this study, high speed synchrotron X-ray experiments are conducted to visualize the in situ deformation and the fracture mechanisms in PBXs composed of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) crystals and hydroxyl-terminated polybutadiene binder doped with iron (III) oxide. A modified Kolsky bar apparatus was used to apply controlled dynamic compression on the PBX specimens, and a high speed synchrotron X-ray phase contrast imaging (PCI) setup was used to record the in situ deformation and failure in the specimens. The experiments show that synchrotron X-ray PCI provides a sufficient contrast between the HMX crystals and the doped binde...

56 citations

02 Jun 2006
TL;DR: In this paper, two basic approaches have been used to derive chemical kinetic models for high explosives: [1] measurement of the reaction rate of small samples by mass loss (thermogravimetric analysis, TGA), heat release (differential scanning calorimetry, DSC), or evolved gas analysis (mass spectrometry, IR, etc.) or inference from larger-scale experiments measuring the critical temperature (T{sub m, lowest T for self-initiation), the time to explosion as a function of temperature, and sometimes a few other results,
Abstract: Prediction of thermal explosions using chemical kinetic models dates back nearly a century. However, it has only been within the past 25 years that kinetic models and digital computers made reliable predictions possible. Two basic approaches have been used to derive chemical kinetic models for high explosives: [1] measurement of the reaction rate of small samples by mass loss (thermogravimetric analysis, TGA), heat release (differential scanning calorimetry, DSC), or evolved gas analysis (mass spectrometry, infrared spectrometry, etc.) or [2] inference from larger-scale experiments measuring the critical temperature (T{sub m}, lowest T for self-initiation), the time to explosion as a function of temperature, and sometimes a few other results, such as temperature profiles. Some of the basic principles of chemical kinetics involved are outlined, and major advances in these two approaches through the years are reviewed.

46 citations