Crack initiation and potential hot-spot formation around a cylindrical defect under dynamic compression

Ma, Xiao; Li, Xinguo; Zheng, Xianxu; Li, Kewu; Hu, Q.Y.; Li, Jianling

doi:10.1063/1.4998679

Cited by 10 publications

(3 citation statements)

References 18 publications

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“…Aluminum alloy, with a density of about one-third of that of steel, has become a common material for improving the impedance matching between the pressure bar and the specimen [71][72][73][74][75][76][77][78][79][80][81][82][83][84][85]. For specimens with smaller wave impedance, such as soft materials and polymer materials, polymeric materials such as polycarbonate (PC), nylon, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), and other polymeric materials can be used as the pressure bar materials [86][87][88][89][90][91][92][93][94][95][96][97][98][99][100][101][102][103][104][105]. Stress waves attenuate and disperse when propagating in viscoelastic pressure bar materials (PC, nylon, PMMA, PET, etc.).…”

Section: Analysis and Matching Study Of Wave Impedance Between Pressu...mentioning

confidence: 99%

“…The second way to solve the problem of weak transmitted pulse signal is to change the measurement method of the stress pulse signal. High-sensitivity materials such as semiconductor strain gauges and quartz piezoelectric crystals are used to replace ordinary foil-resistance strain gauges, and accurate transmitted pulse signals can be measured via increasing the signal-to-noise ratio [80,83,90,100,104,127]. Compared with the resistance strain gauge, the semiconductor strain gauge can improve the signal-to-noise ratio by about 50 times, and the quartz crystal can improve the signal-to-noise ratio by about 3000 times.…”

Section: Analysis and Matching Study Of Wave Impedance Between Pressu...mentioning

confidence: 99%

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Review of SHPB Dynamic Load Impact Test Characteristics and Energy Analysis Methods

Yang,

Li,

Qiao

2023

Processes

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Since the split-Hopkinson pressure bar (SHPB) test technology was proposed, it has played an important role in the study of dynamic mechanical properties of materials under the impact of dynamic load. It is a major test technology for the study of dynamic mechanical properties of materials. The expansion of the range of materials studied has also posed a challenge to the SHPB test technique, requiring some improvements to the conventional SHPB test apparatus and analysis methods to meet the test conditions and ensure the accuracy of its results. Based on a systematic review of the development of the SHPB test technique and the test principles, the main factors that influence the test’s ability to meet the two basic assumptions at this stage are analyzed, and the ways to handle them are summarized. The stress wave dispersion phenomenon caused by the transverse inertia effect of the pressure bar means that the test no longer satisfies the one-dimensional stress wave assumption, while the pulse-shaping technique effectively reduces the wave dispersion phenomenon and also has the effect of achieving constant strain rate loading and promoting the dynamic stress equilibrium of the specimen. Impedance matching between the pressure bar and specimen effectively solves the problem of the test’s difficulty because the transmitted signal is weak, and the assumption that the stress/strain is uniformly distributed along the length of the specimen is not satisfied when studying low-wave impedance material with the conventional SHPB test device. The appropriate pressure bar material can be selected according to the value of the wave impedance of the test material. According to the wave impedance values of different materials, the corresponding suggestions for the selection of pressure bar materials are given. Moreover, a new pressure bar material (modified gypsum) for materials with very-low-wave impedance is proposed. Finally, for some materials (foamed concrete, aluminum honeycomb, porous titanium, etc.) that cannot meet the two basic assumptions of the test, the Lagrangian analysis method can be combined with SHPB test technology application. Based on the analysis and calculation of the energy conservation equation, the dynamic constitutive relationship of the materials can be obtained without assuming the constitutive relationship of the experimental materials.

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Section: Analysis and Matching Study Of Wave Impedance Between Pressu...mentioning

confidence: 99%

Section: Analysis and Matching Study Of Wave Impedance Between Pressu...mentioning

confidence: 99%

Review of SHPB Dynamic Load Impact Test Characteristics and Energy Analysis Methods

Yang,

Li,

Qiao

2023

Processes

View full text Add to dashboard Cite

show abstract

“…Under dynamic compression, most of the cracking in crystals is due to tensile stress generated by diametral compression applied through the contacts between the crystals. Ma et al [19,20] studied the laws of crack initiation and propagation around a cylindrical defect in an explosive simulant using a set of modified split Hopkinson pressure bars equipped with a fluorescence temperature-sensing device. A new phenomenon was observed in which an opening-mode crack emerged from the cylindrical defect earlier than a shearing-mode crack.…”

Section: Introductionmentioning

confidence: 99%

A Modified Set of Constitutive Models for Polymer‐Bonded Explosives that Consider Heterogeneity of Initial Cracks and Failure of Damaged Granules

Qingpeng

li³

et al. 2022

Propellants Explo Pyrotec

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Non-shock ignition of explosions in solids by dynamic loading is a key topic in the field of explosives safety research. Cracks and other damage in polymer-bonded explosives greatly affect non-shock ignition. In this study, we developed a modified set of constitutive models that incorporate heterogeneity of initial cracks and failure of damaged granules, both of which can affect the thermody-namic response and non-shock ignition of condensed explosives. Moreover, the models were used to predict the distribution of cracks and damage under dynamic compression. The calculated results were in good agreement with experiment, which confirmed the validity of the models.

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Measuring Crack Growth and Rise in Temperature around a Cylindrical Defect in Explosive Simulants under Low‐Pressure and Long‐Pulse Loadings

Zhang

Shang

et al. 2020

Propellants Explo Pyrotec

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Low-pressure and long-pulse loadings are critical loading modes in research on non-shock ignition. Under such loadings, viscoplastic deformation, fracture, and a local rise in temperature may occur around inherent defects in condensed explosives to cause non-shock ignition. In this study, transparent poly(methyl methacrylate) was chosen as an explosive simulant to elucidate the processes of crack growth, pore collapse, and rise in temperature at a cylindrical defect by using a set of modified split Hopkinson pressure bars. A recently developed optical temperaturesensing technique that uses the multiphonon-assisted anti-Stokes-to-Stokes fluorescence intensity ratio was used to monitor the rise in temperature in the cracks. By combining the work here with our previous research, two significant conclusions are arrived at: 1) Around the cylindrical defect, the opening-mode crack initiated earlier than the shearingmode crack did but its rate of propagation was considerably lower. Moreover, the smaller the cylindrical defect was, the lower was the rate of propagation of the cracks. 2) The rise in temperature in shearing-mode cracks was higher than that of the opening-mode cracks. It can be inferred that the local rise in temperature caused by shearing was the major factor leading to the non-shock ignition of condensed explosives

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Crack initiation and potential hot-spot formation around a cylindrical defect under dynamic compression

Cited by 10 publications

References 18 publications

Review of SHPB Dynamic Load Impact Test Characteristics and Energy Analysis Methods

Review of SHPB Dynamic Load Impact Test Characteristics and Energy Analysis Methods

A Modified Set of Constitutive Models for Polymer‐Bonded Explosives that Consider Heterogeneity of Initial Cracks and Failure of Damaged Granules

Measuring Crack Growth and Rise in Temperature around a Cylindrical Defect in Explosive Simulants under Low‐Pressure and Long‐Pulse Loadings

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