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SHPB device for acquiring half sinusoids at different loading rates and use method thereof

A technology of half sine wave and loading rate, which is applied in the direction of measuring devices, testing material strength and instruments using one-time impact force, which can solve the problems of placement of loading shapers, gaps in bonding surfaces, low repeatability, etc., and achieve cost saving. Positive timing, improved accuracy, and small dispersion effects

Inactive Publication Date: 2017-10-03
NORTHEASTERN UNIV LIAONING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in the current SHPB test, the same pendulum is carried out at different impact velocities, such as Figure 4 As shown, the rise time of the stress wave obtained at different impact speeds of the same pendulum decreases with the increase of the impact speed, which means that although an impact can obtain a half-sine wave at a specific speed, However, as the impact velocity changes, the shape of the waveform will also change, from the original half-sine wave to a non-half-sine wave
In this way, it cannot be guaranteed that the deformation obtained at all speeds is not diffused during the test, so it will affect the accuracy of the test results obtained
[0004] Therefore, it is necessary to adjust the waveform at different speeds. Generally, the waveform shaping is achieved by combining single-layer or multi-layer shapers of different materials. However, since the shaper and the impact rod are bonded by vaseline and other adhesives, the bonding surface There are gaps, deviations in the placement of the loading shaper, etc., and this method has the disadvantage of low repeatability

Method used

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  • SHPB device for acquiring half sinusoids at different loading rates and use method thereof
  • SHPB device for acquiring half sinusoids at different loading rates and use method thereof
  • SHPB device for acquiring half sinusoids at different loading rates and use method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0048] Preset the incident stress wave duration T = 300μs, impact velocity v = 3.0m / s.

[0049] (1) Fitting of the relationship between the duration of the incident stress wave and the weight of the hammer head: choose hammer heads with a weight of 2.0kg, 3.0kg, 4.0kg and 5.0kg for the impact test, record the data of the duration of the incident stress wave, and compare the duration of the incident stress wave with The data of the weight of the hammer head is fitted, and the corresponding relationship T=45.77W+132 is obtained, such as Figure 5 shown

[0050] (2) Fitting of the relationship between the rising edge time and the radius of curvature: select hammer heads with a radius of curvature of 40mm, 70mm, 100mm, 130mm and 160mm to conduct impact tests under the condition of impact velocity v=3.0m / s, and test the rising edge Fit the time and the curvature radius data to obtain the corresponding relationship between the rising edge time t and the curvature radius SR at this ...

Embodiment 2-4

[0056] The duration of the incident stress wave is preset as T=300 μs, the impact velocity v is set to 2.5 m / s, 3.5 m / s, and 4.0 m / s respectively, and other conditions are the same as those in Example 1. The relevant data are shown in Table 1.

[0057] Table 1

[0058]

[0059] Figure 10 It is the half-sine wave waveform generated under different loading rates of the present invention. As shown in the figure, the present invention respectively obtains incident stress waves with loading rates of 0.514MPa / μs, 0.629MPa / μs, 0.908MPa / μs and 1.245MPa / μs. The duration T of the four incident stress waves is 300μs, and the actual rising edge times t are 143μs, 142μs, 141μs and 143μs, respectively, which are within 1% error range and are close to half-sine waves. It can be seen that the method of the present invention can obtain half-sine waves close to standard half-sine waves at different loading rates.

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Abstract

The invention belongs to the technical field of impact dynamics and discloses a SHPB device for acquiring half sinusoids at different loading rates and a use method thereof. The device comprises a pendulum bob support, a pendulum bob, a cross laser calibration bearing base, an entrance rod and a transmission rod. The top of the pendulum bob support is provided with a dial and a pointer. The pendulum bob comprises a bob bar and a bob head. The bob bar can drive the pointer to carry out circling motion around the axle. The impact end surfaces of the bob head are cambered surfaces and have different curvature radiuses. One side of the pendulum bob support is provided with the cross laser calibration bearing base. The cross laser calibration bearing base is provided with the entrance rod and the transmission rod moving along the axial direction. The entrance rod and the transmission rod are respectively provided with strain gages. The strain gages are connected to an oscilloscope recorder, an exchanger and a computer through a signal preamplifier. The device can acquire half-sine incident stress wave having small dispersivity and good repeatability at different incident stress wave time and different loading rates and improve test accuracy.

Description

technical field [0001] The invention relates to the technical field of shock dynamics, in particular to a SHPB device for obtaining half-sine waves at different loading rates and a method for using the same. Background technique [0002] When the half sine wave propagates in the SHPB (separated Hopkinson pressure bar) device, it will not have a large waveform dispersion phenomenon like a rectangular wave, and it can better satisfy the one-dimensional stress wave propagation theory, and the obtained test results are also It will be more accurate accordingly, and can provide reliable test conditions for studying the dynamic mechanical properties of concrete and rock materials with larger particles. Therefore, for the large-diameter SHPB device, it is a necessary condition to ensure the success of the test to use the half-sine wave for the rock impact test. [0003] In the SHPB test, different loading rates are mainly obtained by adjusting the impact velocity of the pendulum. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/30G01N3/02
CPCG01N3/30G01N3/02G01N2203/0039
Inventor 朱万成李少华牛雷雷魏晨慧代风于淼
Owner NORTHEASTERN UNIV LIAONING
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