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Liu W.,Nanjing University of Science and Technology | Sun X.-X.,Nanjing University of Science and Technology | Sun X.-X.,Liaoning North Huafeng special Chemical Ltd Company | Shen R.-Q.,Nanjing University of Science and Technology | Ye Y.-H.,Nanjing University of Science and Technology
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2014

The dispersion effect in the Hopkinson pressure bar high-g loading technique is caused by the lateral inertia motion of particle, leading to an inaccurate acceleration in peak and duration. Based on the Fast Fourier Transform (FFT) approach, the dispersion effect was corrected. Then, acceleration pulses at different locations along the pressure bar were compared to check the dispersion effect. In addition, before and after dispersion correction, the acceleration pulses on the specimen were investigated under different pulse loadings, and the errors of the peak and duration were analyzed. The results show that the acceleration pulses at different locations of the bar are different in peak and duration due to the dispersion effect, and the error of the peak acceleration on the initiator is more than 10%. The error of the acceleration duration depends on the pulse shape, but the absolute error is less than 6μs. As for the dispersive pulse, dispersion correction is a necessary procedure to obtain a more accurate acceleration pulse. Source


Sun X.-X.,Nanjing University of Science and Technology | Sun X.-X.,Liaoning North Huafeng special Chemical Ltd Company | Liu W.,Nanjing University of Science and Technology | Shen R.-Q.,Nanjing University of Science and Technology | And 2 more authors.
Hanneng Cailiao/Chinese Journal of Energetic Materials | Year: 2014

To improve the anti-overloading ability of initiating explosive device under ammunition penetration target, polytetrafluoroethylene (PTFE) materials with varied thickness were added at the bottom or the outer wall of detonators to weaken the impact stress wave and the strength of inertial overload. The standard one-leg bridge-wire electric detonators were used as strengthening object. The mechanism and effectiveness of this reinforcement method were studied by gas gun experiment and numerical simulation. Experiment and the simulation results show that the buffer layer isolates the impact stress wave and cushions the mass inertia of the detonators. With the increase of gasket thickness, the overload acceleration and overload damage of detonator decrease gradually. When the buffer layer thickness is greater than 0.9 mm, the detonator has no obvious damage. The addition of PTFE materials on the detonator has an obvious protective function. Source


Sun X.X.,Nanjing University of Science and Technology | Sun X.X.,Liaoning North Huafeng special Chemical Ltd Company | Liu W.,Nanjing University of Science and Technology | Shen R.Q.,Nanjing University of Science and Technology | And 2 more authors.
Applied Mechanics and Materials | Year: 2014

The thin-walled shell axial impact deformation of one-leg electric detonator with different density charge was studied. The impact stress was analyzed, and on the basis of kinetic theory the impact deformation model was established for the thin-walled shell filled with explosive. The experiments were verified at 60 000g, 80 000g, 100 000g and 120 000g by gas gun. The results show that shell length decreases and the plastic deformation zone diameter increases after impact. Damage deformation degree decreases with increased shell strength, reduced shell and internal charging mass summation and reduced impact velocity square. The model calculated value agrees well with the test data. The deformation model can be used to predict overload damage deformation for such detonator. © (2014) Trans Tech Publications, Switzerland. Source


Sun X.,Nanjing University of Science and Technology | Sun X.,Liaoning North Huafeng special Chemical Ltd Company | Liu W.,Nanjing University of Science and Technology | Shen R.,Nanjing University of Science and Technology | And 3 more authors.
Guti Lixue Xuebao/Acta Mechanica Solida Sinica | Year: 2014

The influences of peak acceleration, loading direction and product structure on the damage and performance of two standard bridgewire electric detonators, namely, one leg and two legs structure, were studied by gas gun at high overload of 60 000 g, 80 000 g, 100 000 g and 120 000 g. The damage laws and damage modes were obtained, which were further analyzed by dynamics theory in conjunction with the product structures. The results show that there are three types of damage modes, namely, local plastic deformation, relative displacement, and brittle damage. A careful observation indicates that a series of processes take place on damage and fracture surface, including impact end deformation, electrode plug moving inward, electrode and fuses incline, electrode plug crack, resistance increase, bridgewire break and increase of output power scattering. The total length change rate increases with the acceleration increasing under output loading mode, and the total length decrease for one leg detonator is caused by electrode plug moving inward, while the total length decrease for two legs detonator results from impact deformation. The resistance of one leg detonator changes obviously under lateral loading mode, with the bridgewire break and detonator explosion occurring occasionally. The output power scattering increases after high-g loading. Source


Sun X.,Nanjing University of Science and Technology | Sun X.,Liaoning North Huafeng special Chemical Ltd Company | Shen R.,Nanjing University of Science and Technology | Liu W.,Nanjing University of Science and Technology | And 2 more authors.
Nanjing Li Gong Daxue Xuebao/Journal of Nanjing University of Science and Technology | Year: 2013

In order to use an air gun to evaluate the anti-overload capacities of initiating explosive devices, investigate the influences of bullet structures on overload environments, obtain the structural damage characteristics of typical electric detonators under high overloads, air gun tests and numerical simulations are conducted. A one leg bridge wire electric detonator is loaded in the axial output direction, and the bullet structure of the air gun is designed. At the bullets' speed of 60 m/s, the influences of the detonator positions in the bullets and with or without a free moving filler block behind the detonators on the damages of the detonators during the processes of the bullets dynamic impact a steel target are researched by means of visual inspection, dimension and resistance measurement and internal structure non-destructive detection of a X-ray perspective instrument. The results show that the damages include electrode plug moving inward, explosive column compression, shell local deformation, shell length decrease and shell diameter increase. The change values and rates of detonator dimensions and resistances have little difference in the tests of three kinds of bullets. The change curves of detonator dimensions have similar shapes and almost equal values in the simulation of the three kinds of bullets. The simulation results agree well with the experimental results. The conditions that the detonator placed in the middle or bottom of the bullet and with or without a free moving filler block behind the detonator have no significant influence on the shock damages. Source

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