CN111413216A - An electromechanical combined loaded Hopkinson torsion bar - Google Patents

Abstract

The invention discloses an electromechanical combined loading type Hopkinson torsion bar. A guide rail is erected on a sleeper, and a center bracket is arranged on the guide rail; On the guide rail, the test piece assembly is placed between the torsional incident rod and the torsional transmission rod; the end of the guide rail near the torsional incident rod is provided with a power system, specifically: an accumulator, an axial strong docking system, rotational power loading and control The system, the rotational energy storage and release system, the circumferential fast loading system and the torsional pulse shaper are connected together in sequence, and the torsional pulse shaper is connected to the torsional incident rod. It makes up for many deficiencies of the existing pre-energy-storage separated Hopkinson torsion bar, explosive-driven Hopkinson torsion bar device, T-shaped Hopkinson torsion bar device, and flywheel type Hopkinson torsion bar device, It greatly reduces the difficulty of the experiment and greatly improves the efficiency of the experiment.

Description

An electromechanical combined loaded Hopkinson torsion bar

Technical field:

The invention belongs to the technical field of experimental equipment for dynamic mechanical properties of materials, in particular to an electromechanical combined loading type Hopkinson torsion bar.

Background technique:

The split Hopkinson rod is an effective experimental device to study the dynamic mechanical properties of materials under one-dimensional stress state. Compared with Hopkinson compression bars and tie bars, Hopkinson torsion bars are particularly suitable for studying the mechanical properties of materials in dynamic shear and pure shear states, and there is no radial inertia effect in the bar. Using the Hopkinson torsion bar dynamic torsion test is the closest to the one-dimensional stress wave assumption, and furthermore, the propagation of the torsional wave in the elastic bar does not occur dispersion. In the 1970s, T. Nicholas et al. invented the pre-energy split Hopkinson torsion bar. The so-called pre-energy split Hopkinson torsion bar divides the torsion incident bar into two parts. One end of the rod is provided with a rotating head for applying external torque (load), and the other end is connected to the specimen (this section is called the pre-torque section). At the boundary of the two sections, a gripping clamp (the main part of which is a bolt with an annular V-shaped groove in the middle) is used to clamp the rod to prevent it from rotating. A jack or other device is used to rotate the rotating head to torsional load the pre-torsion section where the torsional deformation energy is pre-stored. When the pre-stored energy value reaches the experimenter's expectation, the experimenter quickly releases the clamping mechanism, and the energy (stress, strain) of the preloaded section is transmitted to the unloaded section of the incident rod in the form of a wave to form a torsional loading wave. The main disadvantages of this approach are:

1. It is difficult for the clamping device to completely clamp the rod without rotation, and it is often necessary to continuously strengthen the clamping force (further tighten the bolt) during the loading process to prevent rotation and sliding. During this process, the bolts often break suddenly, causing the experiment to fail.

2. This kind of pre-energy torsion bar releases the clamp by twisting the bolt with the annular V-shaped groove in the middle during the experiment, and the process of twisting the bolt is very random, which seriously affects the repetition of the experimental conditions of the waveform. sex.

In 1971, Duffy et al. proposed a novel explosive loading method. Two rotating blades are fixed symmetrically (on the same diameter) on both sides of the loading end of the incident rod, and the two groups of explosive packs are symmetrically arranged on the same side of the two rotating blades. During loading, the two packs of explosives are simultaneously ignited through the parallel connection of the fuse, and the impact force generated by the explosion is equivalent to applying a pair of force couples to the loading rod, forming a torsional wave and completing the instantaneous loading of the dynamic torsional load. Compared with the pre-torque loading method, explosive impact loading can avoid the problems that the fixture pressure is not easy to control and the experiment is easy to fail, and the explosive loading is also transient, which can greatly reduce the rise of the stress wave front, but there are also obvious shortcomings. : (1) Due to the influence of unpredictable factors such as the composition and quantity of explosives being difficult to precisely control and the explosives being damp, the loading torque cannot be precisely controlled, and the experiment repeatability is poor; (2) During the explosive loading process, the specimen is actually subjected to variable strain rate loading effect, that is, it is difficult to ensure constant strain rate loading with the commonly used explosion loading method. Therefore, this method has not been widely used.

In 2013, Jiang Xiquan and others invented the T-shaped split Hopkinson torsion bar, which almost overcomes all the shortcomings of the pre-energy torsion bar. However, due to structural reasons, complex bending waves are inevitably generated in the conversion device, and such bending waves are difficult to eliminate, and will be introduced into the torsional incident rod. In addition, for a torsion bar with a large diameter (such as 1000mm), it takes a long time for the wave to propagate on the cross section of the bar, and at the same time, the wave has spread along the axial direction, so the rising edge of the torsional incident wave cannot be steep, which affects the increased experimental strain rate.

In 2015, Fang Qin et al. invented the flywheel Hopkinson torsion bar, which solved the bending wave problem caused by asymmetric loading of the T-shaped split Hopkinson torsion bar and the torsional incident wave caused by the excessive cross section of the rod (tube). The rising edge cannot be steep. However, since the contact between the flywheel and the end surface of the incident rod is through axial movement, the torque transmission requires friction between the surfaces. Since it takes a certain amount of time from the initial contact to the complete contact (there is no relative movement between the surfaces), this As a result, the rising edge of the torsion pulse generated in this way is too long to meet the requirements of the conventional Hopkinson torsion bar.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies in the prior art, the present invention provides an electromechanical combined loading Hopkinson torsion bar.

The present invention solves the technical problem by adopting the following technical solutions:

An electromechanical combined loading type Hopkinson torsion bar, comprising: a bracket part, the bracket part includes a base bracket on which a sleeper is arranged;

a guide rail, the guide rail is erected on the sleeper, and a center bracket is arranged on the guide rail;

Twist the incident rod;

Twist the transmission rod;

Wherein, the torsional incident rod and the torsional transmission rod are fixed on the guide rail through a central support provided on the guide rail, and the test piece assembly is placed between the torsional incident rod and the torsional transmission rod;

One end of the guide rail close to the torsional incident rod is provided with a power system, specifically: an accumulator, an axial strong docking system, a rotary power loading and control system, a rotary energy storage and release system, a circumferential fast loading system and a torsional pulse shaping system The torsional pulse shapers are in turn connected together, and the torsional pulse shaper is connected to the torsional incident rod.

Preferably, the axial strong docking system, the rotational power loading and control system and the rotational energy storage and release system are rigidly connected together.

Preferably, adjustment feet are provided under the base support.

Preferably, an adjustable base is provided at the bottom of the axial strong docking system, the rotary power loading and control system, the rotary energy storage and release system, and the circumferential fast loading system, and is arranged on the guide rail through the adjustable base.

Preferably, the circumferential rapid loading system includes a torsional pulse output shaft and a shaftless inner disc,

The shaftless inner collision disc is a concave disc;

One end of the torsional pulse output shaft is provided with an outwardly convex fork, and the shaft-free inner-impact disc is suspended and supported on the outer circumference of the torsion pulse output shaft. Dynamic torsion pulses are formed in the torsion pulse output shaft.

Preferably, the circumferential rapid loading system further includes a rotational residual kinetic energy absorption system.

Preferably, the torsional pulse shaper is a thin-walled cylindrical structure with flanges at both ends, and the torsional pulse in the torsional pulse output shaft is shaped into the torsional pulse required for the test.

Compared with the prior art, the present invention has the following technical effects:

In the present invention, the non-shaft internal impact disc rotates and strikes the torsional pulse output shaft, and a transient torsional (shear stress) pulse is generated in the torsional pulse output shaft. Through the pulse shaper, a required input rod end is directly applied to the incident rod end. Pulse torque makes up for many deficiencies of the existing pre-energy-storage split Hopkinson torsion bar, explosive-driven Hopkinson torsion bar device, T-shaped Hopkinson torsion bar device, and flywheel Hopkinson torsion bar device It greatly reduces the difficulty of the experiment and greatly improves the efficiency of the experiment.

Other features and advantages of the present invention will be described in detail in the detailed description which follows.

Description of drawings:

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort;

1 is a front view of an electromechanical combined loaded Hopkinson torsion bar provided by the present invention, and FIG. 2 is a sectional view of the C-C section in FIG. 1;

Description of the symbols in the figure: 1. Accumulator, 2. Axial strong docking system, 3. Rotational power loading and control system, 4. Rotational energy storage and release system, 5. Circumferential fast loading system, 5-1 Rotation remaining Kinetic energy absorption system, 5-2 torsional pulse output shaft, 5-3 shaftless inner impact disc, 6. torsional pulse shaper, 7. torsional incident rod, 8. center support, 9. specimen assembly, 10. torsion Transmission rod, 11. Guide rail, 12. Sleeper, 13. Foundation bracket, 14. Adjustable foot, 15. Adjustable base 1, 16. Adjustable base 2, 17. Adjustable base 3.

Specific implementation structure:

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments.

As shown in Figure 1-2, an electromechanical combined loading Hopkinson torsion bar includes 1. Accumulator, 2. Axial strong docking system, 3. Rotary power loading and control system, 4. Rotary energy storage and release system , 5. Circumferential fast loading system, 6. Torsion pulse shaper, 7. Torsion incident rod, 8. Center support, 9. Specimen assembly, 10. Torsion transmission rod, 11. Guide rail, 12. Sleeper, 13. Basic bracket, 14. Adjustable feet, 15. Adjustable base 1, 16. Adjustable base 2, 17. Adjustable base 3.

The circumferential fast loading system includes 5-1 rotational residual kinetic energy absorption system, 5-2 torsional pulse output shaft, 5-3 shaftless inner impact disc;

The shaftless inner collision disc is a concave disc;

One end of the torsional pulse output shaft is provided with an outwardly convex fork, and the shaft-free inner-impact disc is suspended and supported on the outer circumference of the torsion pulse output shaft. Dynamic torsion pulses are formed in the torsion pulse output shaft.

The torsional pulse shaper is a thin-walled cylindrical structure with flanges at both ends, and the torsional pulse in the torsional pulse output shaft is shaped into the torsional pulse required for the test.

First, the accumulator is charged with a certain pressure of high-pressure gas, ready to be released at any time to push the 2, 3, 4 component assembly. Electricity activates the rotary power loading and control system 3, and drives the rotary energy storage and release system 4 to perform high-speed rotary motion to store a certain amount of rotational kinetic energy. Then release the high-pressure gas in the accumulator 1, push the components 2, 3, and 4 for rapid axial movement, hit and hook the shaftless inner collision disc 5-3, and drive it to rotate with the rotating energy storage and release system 4 rotate at the same speed. The shaftless inner collision disc 5-3 rotates at a certain angle and then strikes the torsion pulse output shaft 5-2, in which a dynamic torsion pulse is generated. The torsional pulse is shaped by the torsional pulse shaper 6 and then enters the torsional incident rod 7 . The shaped pulse propagates toward the end of the specimen in the incident rod, and reflects and transmits at the specimen. The reflected signal forms a reflected pulse in the incident rod and transmits to the loading end of the incident rod; the transmitted signal forms a transmitted pulse and propagates to the free end of the transmission rod. Record the incident pulse, reflected pulse and transmission pulse. According to the one-dimensional stress wave theory, the dynamic shear stress, dynamic shear strain and strain rate of the specimen 5 can be processed and obtained, and the shear stress of the specimen material at a certain strain rate can be obtained. Shear stress-strain curve.

After the torsional pulse output shaft 5-2 rotates at a certain angle, it is blocked and stops rotating. At this time, the rotary energy storage and release system 4 is disconnected from the rotary power loading and control system 3, and the rotary energy storage and release system 4 is in a forced braking state; The rotating parts in the loading and control system 3 enter a state of free rotation, and finally stop rotating slowly under the action of friction torque.

The invention makes up for many deficiencies of the existing pre-energy storage type separated Hopkinson torsion bar, explosive-driven Hopkinson torsion bar device, T-shaped Hopkinson torsion bar device and flywheel type Hopkinson torsion bar device It greatly reduces the difficulty of the experiment and greatly improves the efficiency of the experiment.

The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments, and the descriptions in the above-mentioned embodiments and the description are only to illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have Various changes and modifications fall within the scope of the claimed invention. The claimed scope of the present invention is defined by the appended claims and their equivalents.

Claims (6)

1. The utility model provides an electromechanical combination loading type hopkinson torsion bar which characterized in that: the support comprises a support part, wherein the support part comprises a basic support, and a sleeper is arranged on the basic support;

the guide rail is erected on the sleeper and is provided with a central support;

twisting the incident rod;

a torsional transmission rod;

the torsion incident rod and the torsion transmission rod are fixed on the guide rail through a central support arranged on the guide rail, and a test piece assembly is arranged between the torsion incident rod and the torsion transmission rod;

one end of the guide rail close to the torsion incident rod is provided with a power system, which specifically comprises: the energy accumulator, the axial powerful butt joint system, the rotary power loading and control system, the rotary energy storage and release system, the circumferential rapid loading system and the torsional pulse shaper are sequentially arranged along the axis, and the torsional pulse shaper is connected with the torsional incident rod.

2. An electromechanical combination loaded hopkinson torsion bar as claimed in claim 1, wherein: the axial powerful butt joint system, the rotary power loading and controlling system and the rotary energy storage and releasing system are rigidly connected together along the axis.

3. An electromechanical combination loaded hopkinson torsion bar as claimed in claim 1, wherein: and an adjusting ground foot is arranged below the basic support.

4. An electromechanical combination loaded hopkinson torsion bar as claimed in claim 1, wherein: the bottom parts of the axial powerful butt joint system, the rotary power loading and control system, the rotary energy storage and release system and the circumferential rapid loading system are provided with adjustable bases, and the adjustable bases are arranged on the guide rail.

5. An electromechanical combination loaded hopkinson torsion bar as claimed in claim 1, wherein: the circumferential rapid loading system comprises a torsional pulse output shaft and a shaftless inner collision disc;

the shaftless inner collision disc is an inwards concave disc;

one end of the torsion pulse output shaft is provided with an outward protruding shifting fork, the shaftless inward collision disc is supported on the periphery of the torsion pulse output shaft in a suspension mode, the shaftless inward collision disc rotates to circumferentially collide with the outward protruding shifting fork of the torsion pulse output shaft, and dynamic torsion pulses are formed in the torsion pulse output shaft.

6. An electromechanical combination loaded hopkinson torsion bar as claimed in claim 1, wherein: the torsion pulse shaper is of a thin-wall cylinder structure with flanges at two ends, and is used for shaping the torsion pulse in the torsion pulse output shaft into the torsion pulse required by the test.

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