Research On The Cause And Mechanism Of The Malfunction Of The Trigger Fuze Ballistic Explosion

In order to provide foundation for fault location of ballistic burst of point detonating fuze and its structure improvement,the effect of launching overload on moisture proof plate of the point detonating fuze,influence of electrical overload orientation on closing threshold of electrical switch is studied.Rainproof performance of cross bar rain insensitive device of M739 fuze.Anti-rain performance and dynamic response of trigger mechanism of M739 fuze which are closely related to the fuze ballistic burst problems are studied on through theoretical analysis,numerical simulation and experimental verification,The effect of launching overload on moisture proof plate of point detonating fuze is studied through simulation and the relationship between deformation of moisture proof plate and launching overload is obtained.The launching overload has limited influence on the deformation of metal moisture proof plate,and there is an approximately linear relationship between the peak of deformation and the peak of launching overload of moisture proof plates of different materials.Fuze crimping has an effect on the deformation of moisture proof plate under launching overload,the larger the length and thickness of the crimping,the smaller the deformation of the moisture proof plate.The thickness of moisture proof plate is approximately linear to its deformation.In order to provide reference for the application of inertial impact switch in electromechanical fuze and provide help for fault location of ballistic burst of this kind of switch,based on exterior ballistic mechanical environment which is closely related to inertial impact electrical switch,theoretical analysis and simulation using Adams conducted.The analysis show that the electrical overload orientation has a great influence on the closing threshold of inertial impact electrical switch.When electrical overload force and vertical axis of electrical switch parts is 35° to 45°,the electrical switch is most easily connected to electricity and the electrical overload force is about 20% smaller than the static situation.The dynamic electrical overload force of electrical switch is about 14% smaller than that of static situation.The influence of assembly orientation of electrical switch and its manufacturing error on the closing threshold of electrical switch can not be ignored.The closing threshold under the extreme size situation(i.e.the minimum contact distance between the connecting pin and the switch cap,the maximum quality of the connecting pin,and the minimum spring resistance)is about 36% smaller than that under the median size situation.In order to evaluate the rainproof performance of related mechanism of the fuze and provide reference for the ballistic burst cause search of the fuze and optimization of the rain insensitive device,a coupled smooth particle hydrodynamics the finite element numerical model is established.ANSYS/LS-DYNA is used to simulate the impact process high-speed raindrop between and cross bar rain insensitive device of M739 fuze,and the dynamic response of the fuze rain insensitive device is obtained.Simulation results show that 08 Al steel rainproof cap can reduce the energy of raindrops by about 85%.When raindrops are blocked and scattered by the rain cap and the five bars,then acts on the trigger mechanism,the impact energy of raindrops can be reduced to about 8% of the initial energy of raindrops.The rotational velocity of the projectile has a great influence on the peak impact force of the trigger mechanism,and its value decreases first and then increases with the increase of the projectile rotational velocity and the variation of peak impact force of the trigger mechanism is up to 50%.The rainproof performance of plastic rain cap is about 78% lower than that of steel rain cap.Resonance failure of the rain cap is impossible when the projectile flies in rain.The material and thickness of grid bar base have little effect on the peak impact force of raindrops acting on each grid bar,and have a great influence on the peak impact force of raindrops acting on the striking pin of the impact mechanism after raindrops are scattered by grid bars.The diameter of the cross bar has a great influence on the peak impact force of raindrops acting on the striking pin of the trigger mechanism.With the increase of the diameter of grid bar,the acting force of raindrop on the trigger mechanism decreases gradually.Compared with the force that the raindrop first acts on the steel grid bar and then acts on the striking pin of the trigger mechanism,the force that the raindrop first acts on the aluminum grid bar and then acts on the striking pin of the trigger mechanism is about 15% higher.but aluminum bar because of plastic deformation can hardly resist the secondary impact of rain.Bars materials should have higher strength and stiffness.At present,cross bar rain insensitive device of M739 fuze can ensure that raindrops with diameter of 5.6mm and speed of 1500 m /s impact without triggering the mechanism in advance.In order to evaluate the safety of the fuze trigger mechanism impacting rain,ANSYS/LS-DYNA is used to conduct numerical simulation of the high-speed raindrop impacting with trigger mechanism,and the dynamic characteristics of raindrop impacting trigger mechanism is obtained.The effects of material of striking pin and supporting cylinder material on the raindrop impact resistance of the impactor are studied.The results show that compared with raindrops of small diameter and high speed,raindrops of large diameter and low speed are more dangerous to the trigger mechanism.The material of striking pin has a great influence on the raindrop impact resistance of the trigger mechanism.Compared with aluminum alloy striking pin,the trigger mechanism of steel has about 39% higher rain impact resistance.The material of surporting cylinder also has a great influence on raindrop impact resistance of the trigger mechanism.Compared with H68 and H96 brass surporting cylinder,trigger mechanism of red copper T2 and red copper T3 has greater raindrop resistance.