Research On Continuous Electric Resistance Testing Mehtod Of Detonation Performance And Driving Characteristics Of Explosives

Explosion testing technique is an important driving force to promote the development of explosion mechanics.Especially in recent years,with the rapid development of electronic and optical instruments,great progress has been made in this field.The main factor limiting the high frequency sampling of explosion and shock signal,at present,is the frequency response of the sensor and the signal conditioning analog circuit.Continuous measuring technique based on resistance wire probe has high dynamic frequency response in theory,eliminating the need of complex optical and electric circuit,and the test results have high relative accuracy for large-scale charge,which is very suitable for the field test of commercial explosives with large quantities.On the other hand,with the popularization of the blasting idea of refinement and digitalization,it is urgent to develop an economical and reliable test method for detonation and driving performance of commercial explosives in order to establish a "big data platform" for engineering blasting.Meanwhile,Computer numerical simulation is now increasingly used for the research of explosion and impact problems such as explosion protection and damage of military targets,weapon terminal effect and engineering blasting,in which the selection of the equation of state(EOS)and its parameters is often the bottleneck limiting calculation precision,especially for commercial explosives with typical non-ideal detonation characteristics.Consequently,it becomes urgent to develop a simple and economical test method for the parametric determination of the EOS.To solve above problems,a new type of pressure-activated velocity probe,with excellent test stability,reliability and anti-interference ability,has been developed,which can continuously record the time history data of explosive detonation wave,shock wave in medium and metal collision point movement.Based on the new probe,the detonation performance of commercial explosives,the near-field shock wave of underwater explosion and the flight attitude of two-dimensional flat plate and circular tube driven by sliding detonation were investigated.And on these bases,the EOS parameters of detonation products were determined.Furthermore,exploratory experiments were carried out to test the high pressure shock adiabatic data of materials.The specific work and results are as follows:(1)A novel Pressure-activated Continuous Velocity Probe(PCVP)and its measuring system were developed.By analyzing the internal and external factors such as electromagnetic wave,cavitation jet,metal jet,channel effect and bending wave theoretically,the novel probe was developed.After that,underwater explosion test was performed to demonstrate the ability of recording continuous travel trajectory of detonation and shock wave for different types of probe.Ls-dyna program and compression test were applied to preliminarily calibrate the conduction pressure of the novel probe.Finally,the threaded wire-metal foil probe with the best comprehensive performance was selected as the test probe for the research of detonation and driving performance of explosives in this paper.Besides,DVP-I Continuous Detonation Velocimeter was also developed as a matching signal acquisition equipment.(2)A series of test methods for determination of detonation properties of commercial explosives,such as detonation velocity,critical diameter,sympathetic detonation and C-J pressure,were designed based on the PCVP,and the main performance parameters were measured afterwards.Concretely,the detonation velocity measurement devices for cylindrical and planar Ammonium Nitrate-Fuel Oil(ANFO)charge and emulsion explosive in simulated deep water environment were designed respectively by the novel probe.The effect of charge density on cylindrical charge,mineral powder content on plane charge and hydrostatic pressure on the detonation velocity of emulsion explosive were investigated by PCVP,respectively.Then,we measured the critical diameter and thickness of ANFO using conical charge and wedge charge equipped with the new probe,and analyzed the diameter effect as well.A test setup with the continuous probe was schemed out,which can be used to record the development process of detonation wave of donor charge and acceptor charge sequentially.Three different types of detonation-shock wave time history curves were given,which realized the quantitative determination of sympathetic detonation.Using water and Plexiglas as standard materials,a modified aquarium test by PCVP,according to impedance matching principle,was designed as well as a simplified arrangement,by which we measured the detonation pressure of ANFO on the ground.Moreover,a paraffin probe was developed to measure the detonation pressure of explosive in borehole.(3)Using the novel continuous probe,underwater explosion testing systems for spherical and cylindrical charge were developed respectively,and the parametric inversion of JWL EOS was carried out.Assembling the novel probe with spherical charge,underwater explosion system for the sphere was then designed.The time history curves of detonation wave and underwater explosion near-field shock wave were obtained by the new probe.We calculated the detonation pressure based on the impedance matching between explosive and water.The polytropic EOS was then determined by the data of underwater explosion of spherical charge,and the attenuation coefficients of peak pressure of near-field shock wave were fitted.Analogously,assembling PCVP with the cylindrical charge,we developed another underwater explosion testing system for the cylinder,whose detonation velocity can be obtained by the probe inside the charge,and the trajectory of oblique shock wave in water can be recorded by the declining probe in water.After that,we obtained the oblique shock wave front of cylindrical charge by the PCVP-based testing system.Based on the oblique shock wave model of two-dimensional steady flow and Prandtl-Meyer flow theory,parameters such as detonation pressure,adiabatic exponent,water-air interface angle,etc.were calculated.Finally,by adjusting the six coefficients of JWL EOS in Autodyn program and comparing the results of experiment and numerical simulation on the peak pressure attenuation of shock wave of spherical charge and the oblique shock wave front of cylindrical until the maximum errors are within allowable range,we determined the JWL EOS parameters of the explosives at last.(4)A trapezoidal bracket continuous velocity probe was developed to measure the flying attitude of two-dimensional flat plate and metal cylinder driven by sliding detonation.First,a pressure-activated trapezoidal bracket continuous velocity probe was put forward,by which the flying attitude measuring devices of flat plate and copper tube were designed respectively.We can determine the detonation velocity from the probe data of parallel section,and the flight attitude from the inclining.Based on the explosive welding setup,we obtained flying attitude curves of explosive welding plates as well as their bending angles and flying speeds,which were compared with the results calculated by Richter formula and the polytropic EOS was then determined.Afterwards,a corresponding numerical simulation was performed,whose results were in good agreement with the experiments and theoretical calculation.A modified cylinder test based on the trapezoidal bracket probe was used to record the expansion trajectory of copper tube.Then the JWL EOS parameters in the test were inversed by comparing the simulation results of radial expansion displacement and velocity of copper tube with the experimental fitting curves.By energy analysis,the Gurney energy and the initial fragment velocity were calculated as well.In addition,using PMMA as standard material,the shock wave parameters in PMMA and water were continuously recorded by PCVP.We obtained partial shock Hugoniot data of water by impedance matching technique and graphical method.