Research On The Insensitivity Transformation Technology Of A Naval Gun Fuze

Based on insensitive ammunition technology,the study on desensitization of a fuze was conducted.The major dangerous situations that the fuze may confront during storage were considered,including the cook-off situation,the sympathetic detonation situation and the fragment-impact situation.It is hoped that through the modification of structure of the fuze and the replacement of original booster explosive to insensitive booster explosive within the fuze,the safety of the fuze can be effectively improved in cook-off situation.It is also hoped that through modification of packaging case of the fuze,the safety of the fuze can be improved in sympathetic detonation situation and fragment-impact situation.First of all,in order to desensitize a fuze in a cook-off situation,a modification scheme for the fuze was proposed.Using ABAQUS,numerical simulation and verification of fast cook-off and slow cook-off were conducted for different schemes that employed different explosive charges and different structures of the fuze body.The results show that the simulation was in reasonable agreement with the experiment,and no ignition reaction occurred within 1000 s.The temperature variation curve of the test sample coincided with the simulated temperature variation curve,which proves that the numerical model was reliable;changing the booster explosive within the fuze to TATB can greatly improve its safety in slow cook-off and fast cookoff;the pressure-relieving hole on the body of the fuze can effectively relieve the pressure of the explosive within the fuze,which reduces its vulnerability in slow cook-off and fast cookoff situations.Secondly,in order to desensitize the fuze with package in a sympathetic detonation situation,modification schemes were proposed.ANSYS/LS-DYNA was used to verify the numerical models with different charge types and different packaging schemes.The results show that the simulation results were in good agreement with experiment,which proves that the numerical models of sympathetic detonation were credible.In the original packaging scheme,the peak pressure of the booster explosive(PBX 9501)did not reach the critical initiation pressure,but it exceeded the allowable stress of the explosive,which should be modified.After the booster explosive of the fuze was changed to TATB,its peak pressure was significantly reduced;with the package size unchanged,a double-layer packaging tube was designed for the fuze.Among all the double-layer packaging schemes,the scheme that worked most effectively against a sympathetic detonation was the inner layer polyethylene resin,the outer layer 45 steel;with the package size unchanged,a three-layer packaging tube was designed for the same fuze.Among all three-layer packaging schemes,the scheme that worked most effectively against a sympathetic detonation was the inner layer 45 steel,the middle layer polyethylene resin,and the outer layer 45 steel;when comparing the double-layer packaging scheme with the three-layer packaging scheme,the three-layer packaging scheme had a better capability to resist sympathetic detonation.The scheme with the inner layer 45 steel,the middle layer polyethylene resin,and the outer layer 45 steel had the best effect among all schemes,including two schemes and three schemes.Thirdly,in order to desensitize the fuze with package in a fragment-impact situation,ANSYS/LS-DYNA was used to perform numerical simulations that include different impact positions,different impact velocities,and different packaging schemes for the fuze.The results show that the bottom center of the packaged fuze was the weakest position,and it should be paid extra attention;The peak pressure of the packaged fuze increased as the speed of the fragment increased,and the time to reach the pressure peak decreased as the speed of the fragment increased;The method to replace the original booster explosive from PBX 9501 to ultra-fine TATB can improve the capacity of the fuze with package to resist the impact of fragment with a velocity of 1000 m/s;Among all double-layer packaging schemes,the scheme that worked most effectively was the inner layer polyurea and the outer layer 45 steel.It can increase the protecting ability of the package to the fragment with a velocity of 1500 m/s,and in the same scheme,it took the longest time to reach the pressure peak.Among all the threelayer packaging schemes,the scheme that worked most effectively was the inner layer 45 steel,the middle layer polyethylene resin,and the outer layer 45 steel.It can increase the protecting ability of the package to the fragment with a velocity of 2000 m/s,and in the same scheme,it took the longest time to reach the pressure peak;Comparing the double-layer packaging scheme and the three-layer packaging scheme for the fuze,the three-layer packaging scheme had a better effect than the double-layer packaging scheme;Considering the cook-off situation and the fragment-impact situation overall,the packaging scheme should be a three-layer packaging scheme with the inner layer 45 steel,the middle layer polyethylene resin,and the outer layer 45 steel.In the end,the transformation scheme of a certain naval gun fuze was to replace the explosive propellant with ultra-fine TATB;a pressure relief hole is provided at the lower position of the side of the fuse body,and a tin-bismuth alloy is added to the pressure relief hole;fuze packaging chooses 45 steel for the inner layer,polyethylene resin for the interlayer,and 45 steel for the outer layer.