scholarly journals Influence of the shaper parameters on the characteristics of acceleration pulses reproduced by mechatronic shock machines

2021 ◽  
Vol 326 ◽  
pp. 00004
Author(s):  
Denis Shtreker ◽  
Mikhail Polishchuck ◽  
Arkadii Popov
Keyword(s):  
Computer Modeling ◽  
Computational Methods ◽  
Elastic Force ◽  
Shock Pulse ◽  
Pulse Shaper ◽  
Pulse Parameters ◽  
Acceleration Pulse ◽  
Peak Value

In this paper the influence of the shaper parameters on the characteristics of acceleration pulses (peak value and duration) reproduced on mechatronic shock machines is analyzed. A comparison of the acceleration pulses obtained experimentally and by computational methods is presented. Recommendations for clarifying the requirements for methodological calculations of pulse parameters are given. The dependence of the elastic force of the shock pulse shaper on its deformation is presented. The influence of this characteristic on the peak value and duration of the acceleration pulse is estimated. The influence of the height of the shaper on the parameters of the acceleration pulses is analyzed. The concept of a device that allows you to automatically change the height of the shaper to obtain a wider range of acceleration pulses is presented. The interaction of the shock table with the shaper by means of computer modeling is modelled. Conclusions about the dependences of the duration and peak value of the acceleration pulses on the parameters of the shaper (stiffness and height) are drawn. Recommendations for selecting the parameters of the shaper to obtain acceleration pulses with the desired parameters are given.

Simulation of Crystallization of Biominerals

2018 ◽  
Vol 48 (1) ◽  
pp. 327-352 ◽  
Author(s):  
Raffaella Demichelis ◽  
Alicia Schuitemaker ◽  
Natalya A. Garcia ◽  
Katarzyna B. Koziara ◽  
Marco De La Pierre ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Computer Modeling ◽  
Computational Methods ◽  
Vital Role ◽  
Biologically Active ◽  
Aqueous Environment ◽  
General Overview ◽  
Particle Stability ◽  
Forms Of Life

Biominerals are crucial materials that play a vital role in many forms of life. Understanding the various steps through which ions in aqueous environment associate to form increasingly structured particles that eventually transform into the final crystalline or amorphous poly(a)morph in the presence of biologically active molecules is therefore of great significance. In this context, computer modeling is now able to provide an accurate atomistic picture of the dynamics and thermodynamics of possible association events in solution, as well as to make predictions as to particle stability and possible alternative nucleation pathways, as a complement to experiment. This review provides a general overview of the most significant computational methods and of their achievements in this field, with a focus on calcium carbonate as the most abundant biomineral.

The Button Head Bullet Effects on the Incident Pulse of Split Hopkinson Press Bar

2015 ◽  
Vol 782 ◽  
pp. 311-315
Author(s):  
Jia Qu ◽  
Geng Chen ◽  
Guang Ping Zou
Keyword(s):  
Elastic Wave ◽  
Wave Length ◽  
Constant Strain Rate ◽  
Peak Stress ◽  
Wave Theory ◽  
Pulse Shaper ◽  
Lagrange Method ◽  
Stress Increase ◽  
Split Hopkinson ◽  
Peak Value

In order to make the specimen deformed under a constant strain rate and the stress in the specimen kept homogeneous, the wave shaper technology was adopted to modify the incidence waves of the normal Split Hopkinson Press Bar. A method of changing the shape of the bullet was suggested to be applied on the SHPB. Bullets with different length and different curvature have been researched in this paper. And the effection of the button head bullet about incidence pulse was simulated with Lagrange method by ANSYS/LS-DYNA. It is shown in the results that changing the curvature of the bullet impact the rising edge of incidence waves, and the peak stress increase with the speed of the bullet increase, the peak stress and length of incidence waves increased with the length of the button head bullet, when the peak stress reached a certain strength, increasing the bullet length could make the stress peak value lasted longer. Due to the reason that the button head bullet was based on the elastic wave theory, the wave length and the max stress of the shaped wave would be controlled conveniently and avoid the shortcoming that the analogue specimens could not be recycled in the normal pulse shaper technology.

Study of Initiator’s Shock-Resistibility Through Impact Using Hopkinson Pressure Bar

2008 ◽  
Vol 33-37 ◽  
pp. 401-406 ◽  
Author(s):  
Qiong Deng ◽  
Yu Long Li ◽  
Tao Suo ◽  
Chun Lin Chen ◽  
Xing Min Chang
Keyword(s):  
Pulse Width ◽  
Wave Theory ◽  
Hopkinson Pressure Bar ◽  
Pulse Shaper ◽  
Finite Element Program ◽  
Analog Simulation ◽  
Critical Acceleration ◽  
Acceleration Pulse ◽  
Element Program ◽  
Pressure Bar

This paper attempted to study the properties of Slapper detonator non-energetic elements through exerting impact on them by Hopkinson Pressure Bar and evaluating the acceleration that samples received in accordance with one-dimensional stress wave theory. The results showed that the velocity pulse width could be controlled and acceleration pulse width be improved by varying the pulse shaper material and strike bar length. And the critical acceleration causing the failure of the initiator was closely connected with acceleration pulse width as well as acceleration amplitude. When the strike bar length were 126 mm, 190 mm, 270 mm and 460 mm, the acceleration pulse width were 58 μs, 93 μs, 130 μs and 160 μs, respectively, and the critical acceleration causing the failure of the initiator were about 240 000 g, 130 000 g, 74 000 g and 72 000 g, respectively. The accurateness and reliability of acceleration value was accredited to the methods of changing sampling frequency, smoothing velocity and acceleration curve, and fitting curve. The FEM analog simulation was also conducted by using the LS-DYNA finite element program. Good agreements were achieved between the acceleration curve and the simulation results.

Measurement of shock pulse parameters by digital instruments

1982 ◽  
Vol 25 (7) ◽  
pp. 595-598
Author(s):  
D. A. Grechinskii ◽  
V. A. Klochko ◽  
V. G. Rygalin
Keyword(s):  
Shock Pulse ◽  
Pulse Parameters

Effect of Acceleration Pulse Shape on Damage of the Specimen under Hopkinson High-g Loading

2013 ◽  
Vol 455 ◽  
pp. 236-241
Author(s):  
Wei Liu ◽  
Rui Qi Shen ◽  
Xiao Xia Sun ◽  
Ying Hua Ye
Keyword(s):  
Axial Strain ◽  
Experimental Tests ◽  
Critical Duration ◽  
Hopkinson Pressure Bar ◽  
Pulse Shaper ◽  
Stress Increment ◽  
Time Step ◽  
Acceleration Pulse ◽  
Pressure Bar ◽  
Cylindrical Lead

Based on the free Hopkinson pressure bar high-g loading technique, the pure cylindrical lead was mounted on the end section of the incident bar as a specimen to obtain the change law of the axial strain with the shape of acceleration pulses. Both the experimental tests without using pulse shaper and numerical simulations under sine-shaped acceleration pulses were performed and axial strain of the specimen was measured. Results revealed that the shape of acceleration pulse shows highly effect on the damage of the specimen. The axial strain of the specimen arises linearly with the increasing of the acceleration peaks whose durations are all 17μs; while, due to the complexity of plastic wave propagation, 135μs is a critical duration at which axial strain reaches to the maximum under the condition of different durations. The final axial strain of the specimen is determined by both the stress level and stress increment in every time step.

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