Laser driven flyer plate technology offers improved safety and reliability for detonation of explosives in industrial applications ranging from mining and stone quarrying to the aerospace and defense industries.This s...Laser driven flyer plate technology offers improved safety and reliability for detonation of explosives in industrial applications ranging from mining and stone quarrying to the aerospace and defense industries.This study is based on developing a safer laser driven flyer plate prototype comprised of a laser initiator and a flyer plate subsystem that can be used with secondary explosives.System parameters were optimized to initiate the shock-to-detonation transition(SDT)of a secondary explosive based on the impact created by the flyer plate on the explosive surface.Rupture of the flyer was investigated at the mechanically weakened region located on the interface of these subsystems,where the product gases from the deflagration of the explosive provide the required energy.A bilayer energetic material was used,where the first layer consisted of a pyrotechnic component,zirconium potassium perchlorate(ZPP),for sustaining the ignition by the laser beam and the second layer consisted of an insensitive explosive,cyclotetramethylene-tetranitramine(HMX),for deflagration.A plexiglass interface was used to enfold the energetic material.The focal length of the laser beam from the diode was optimized to provide a homogeneous beam profile with maximum power at the surface of the ZPP.Closed bomb experiments were conducted in an internal volume of 10 cm^(3) for evaluation of performance.Dependency of the laser driven flyer plate system output on confinement,explosive density,and laser beam power were analyzed.Measurements using a high-speed camera resulted in a flyer velocity of 670±20 m/s that renders the prototype suitable as a laser detonator in applications,where controlled employment of explosives is critical.展开更多
Nanodiamonds(NDs)have been widely explored for applications in drug delivery,optical bioimaging,sensors,quantum computing,and others.Room-temperature nanomanufacturing of NDs in open air using confined laser shock det...Nanodiamonds(NDs)have been widely explored for applications in drug delivery,optical bioimaging,sensors,quantum computing,and others.Room-temperature nanomanufacturing of NDs in open air using confined laser shock detonation(CLSD)emerges as a novel manufacturing strategy for ND fabrication.However,the fundamental process mechanism remains unclear.This work investigates the underlying mechanisms responsible for nanomanufacturing of NDs during CLSD with a focus on the laser-matter interaction,the role of the confining effect,and the graphite-to-diamond transition.Specifically,a first-principles model is integrated with a molecular dynamics simulation to describe the laser-induced thermo-hydrodynamic phenomena and the graphite-to-diamond phase transition during CLSD.The simulation results elucidate the confining effect in determining the material’s responses to laser irradiation in terms of the temporal and spatial evolutions of temperature,pressure,electron number density,and particle velocity.The integrated model demonstrates the capability of predicting the laser energy threshold for ND synthesis and the efficiency of ND nucleation under varying processing parameters.This research will provide significant insights into CLSD and advance this nanomanufacturing strategy for the fabrication of NDs and other high-temperature-high-pressure synthesized nanomaterials towards extensive applications.展开更多
A simplified theoretic method and numerical simulations were carried out to investigate the characterization of propagation of transverse shock wave at wedge supported oblique detonation wave.After solution validation...A simplified theoretic method and numerical simulations were carried out to investigate the characterization of propagation of transverse shock wave at wedge supported oblique detonation wave.After solution validation,a criterion which is associated with the ratio Φ （u 2 /u CJ） of existence or inexistence of the transverse shock wave at the region of the primary triple was deduced systematically by 38 cases.It is observed that for abrupt oblique shock wave （OSW）/oblique detonation wave （ODW） transition,a transverse shock wave is generated at the region of the primary triple when Φ 〈 1,however,such a transverse shock wave does not take place for the smooth OSW/ODW transition when Φ 〉 1.The parameter Φ can be expressed as the Mach number behind the ODW front for stable CJ detonation.When 0.9 〈 Φ 〈 1.0,the reflected shock wave can pass across the contact discontinuity and interact with transverse waves which are originating from the ODW front.When 0.8 〈 Φ 〈 0.9,the reflected shock wave can not pass across the contact discontinuity and only reflects at the contact discontinuity.The condition （0.8 〈 Φ 〈 0.9） agrees well with the ratio （D ave /D CJ） in the critical detonation.展开更多
文摘Laser driven flyer plate technology offers improved safety and reliability for detonation of explosives in industrial applications ranging from mining and stone quarrying to the aerospace and defense industries.This study is based on developing a safer laser driven flyer plate prototype comprised of a laser initiator and a flyer plate subsystem that can be used with secondary explosives.System parameters were optimized to initiate the shock-to-detonation transition(SDT)of a secondary explosive based on the impact created by the flyer plate on the explosive surface.Rupture of the flyer was investigated at the mechanically weakened region located on the interface of these subsystems,where the product gases from the deflagration of the explosive provide the required energy.A bilayer energetic material was used,where the first layer consisted of a pyrotechnic component,zirconium potassium perchlorate(ZPP),for sustaining the ignition by the laser beam and the second layer consisted of an insensitive explosive,cyclotetramethylene-tetranitramine(HMX),for deflagration.A plexiglass interface was used to enfold the energetic material.The focal length of the laser beam from the diode was optimized to provide a homogeneous beam profile with maximum power at the surface of the ZPP.Closed bomb experiments were conducted in an internal volume of 10 cm^(3) for evaluation of performance.Dependency of the laser driven flyer plate system output on confinement,explosive density,and laser beam power were analyzed.Measurements using a high-speed camera resulted in a flyer velocity of 670±20 m/s that renders the prototype suitable as a laser detonator in applications,where controlled employment of explosives is critical.
基金National Science Foundation(NSF)under award numbers CMMI-1826439 and CMMI-1825739。
文摘Nanodiamonds(NDs)have been widely explored for applications in drug delivery,optical bioimaging,sensors,quantum computing,and others.Room-temperature nanomanufacturing of NDs in open air using confined laser shock detonation(CLSD)emerges as a novel manufacturing strategy for ND fabrication.However,the fundamental process mechanism remains unclear.This work investigates the underlying mechanisms responsible for nanomanufacturing of NDs during CLSD with a focus on the laser-matter interaction,the role of the confining effect,and the graphite-to-diamond transition.Specifically,a first-principles model is integrated with a molecular dynamics simulation to describe the laser-induced thermo-hydrodynamic phenomena and the graphite-to-diamond phase transition during CLSD.The simulation results elucidate the confining effect in determining the material’s responses to laser irradiation in terms of the temporal and spatial evolutions of temperature,pressure,electron number density,and particle velocity.The integrated model demonstrates the capability of predicting the laser energy threshold for ND synthesis and the efficiency of ND nucleation under varying processing parameters.This research will provide significant insights into CLSD and advance this nanomanufacturing strategy for the fabrication of NDs and other high-temperature-high-pressure synthesized nanomaterials towards extensive applications.
文摘A simplified theoretic method and numerical simulations were carried out to investigate the characterization of propagation of transverse shock wave at wedge supported oblique detonation wave.After solution validation,a criterion which is associated with the ratio Φ （u 2 /u CJ） of existence or inexistence of the transverse shock wave at the region of the primary triple was deduced systematically by 38 cases.It is observed that for abrupt oblique shock wave （OSW）/oblique detonation wave （ODW） transition,a transverse shock wave is generated at the region of the primary triple when Φ 〈 1,however,such a transverse shock wave does not take place for the smooth OSW/ODW transition when Φ 〉 1.The parameter Φ can be expressed as the Mach number behind the ODW front for stable CJ detonation.When 0.9 〈 Φ 〈 1.0,the reflected shock wave can pass across the contact discontinuity and interact with transverse waves which are originating from the ODW front.When 0.8 〈 Φ 〈 0.9,the reflected shock wave can not pass across the contact discontinuity and only reflects at the contact discontinuity.The condition （0.8 〈 Φ 〈 0.9） agrees well with the ratio （D ave /D CJ） in the critical detonation.
