A electromechanical combined loading Hopkinson torsion bar

Abstract

The invention discloses an electromechanical combined loading Hopkinson torsion bar, wherein a guide rail is mounted on a sleeper, and a central bracket is arranged on the guide rail; the torsion incident rod and the torsion transmission rod are fixed on the guide rail through the central bracket arranged on the guide rail, and a test piece assembly is placed between the torsion incident rod and the torsion transmission rod; a power system is arranged at one end of the guide rail close to the torsion incident rod, specifically: an accumulator, an axial strong docking system, a rotational power loading and control system, a rotational energy storage and release system, a circumferential rapid loading system and a torsion pulse shaper are connected together in sequence, and the torsion pulse shaper is connected to the torsion incident rod. The invention makes up for many shortcomings of the existing pre-energy storage type separated Hopkinson torsion bar, the explosive-driven Hopkinson torsion bar device, the T-shaped Hopkinson torsion bar device, and the flywheel Hopkinson torsion bar device, greatly reduces the difficulty of the experiment, and greatly improves the efficiency of the experiment.

Description

Technical field:

[0001] The invention belongs to the technical field of material dynamic mechanical property experimental equipment, and in particular relates to an electromechanical combined loading type Hopkinson torsion bar. Background technology:

[0002] The split Hopkinson bar is an effective experimental device for studying the dynamic mechanical properties of materials under one-dimensional stress state. Compared with the Hopkinson compression bar and tension bar, the Hopkinson torsion bar is particularly suitable for studying the mechanical properties of materials under dynamic shear and pure shear state, and there is no radial inertia effect in the bar. The dynamic torsion test using the Hopkinson torsion bar is closest to the one-dimensional stress wave hypothesis. Moreover, the propagation of torsion waves in the elastic bar will not be diffused. In the 1970s, T Nicholas and others invented the pre-energy storage type split Hopkinson torsion bar. The so-called pre-energy storage type split Hopkinson torsion bar is to divide the torsion incident bar into two. One end of the bar has a rotating head for adding external torque (load), and the other end is connected to the specimen (this section is called the pre-torsion section). At the boundary between the two sections, a clamping clamp (the main part of which is a bolt with an annular V-groove in the middle) is used to clamp the bar to prevent it from rotating. The rotating head is rotated by a jack or other device to torsionally load the pre-twisted section, and torsional deformation energy is pre-stored on this section. When the pre-stored energy value reaches the experimenter's expected value, the experimenter quickly releases the clamping mechanism, and the energy (stress, strain) of the pre-loaded 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 method are:

[0003] 1. It is difficult for the clamping device to completely clamp the rod without rotation. Often, the clamping force must be continuously strengthened (the bolts must be tightened further) during the loading process to prevent rotation and sliding. In this process, the bolts often break suddenly, causing the experiment to fail.

[0004] 2. During the experiment, the pre-energy storage torsion bar releases the clamp by twisting off the bolt with an annular V-groove in the middle. However, the process of twisting off the bolt is highly random, which seriously affects the repeatability of the experimental conditions of the waveform.

[0005] In 1971, Duffy et al. proposed a novel explosive loading method. Two rotating blades were fixed symmetrically (on the same diameter) on both sides of the incident rod loading end, and two groups of explosive packs were symmetrically arranged on the same side of the two rotating blades. During loading, the two packs of explosives were ignited simultaneously through the parallel connection of the fuse. The impact force generated by the explosion was equivalent to applying a pair of force couples to the loading rod, forming a torsion wave and completing the instantaneous loading of the dynamic torsion load. Compared with the pre-torque loading method, explosive impact loading can avoid the problem of difficult control of the clamp pressure and easy failure of the experiment. In addition, explosive loading also has the characteristics of instantaneity, which can greatly reduce the rise time of the stress wave front. However, there are also obvious shortcomings: (1) Due to the influence of unpredictable factors such as the difficulty in accurately controlling the composition and quantity of the explosives and the influence of moisture on the explosives, the loading torque cannot be accurately controlled and the experimental repeatability is poor; (2) During the explosive loading process, the specimen is actually subjected to variable strain rate loading, that is, the commonly used explosive loading method is difficult to ensure constant strain rate loading. Therefore, this method has not been widely used.

[0006] In 2013, Jiang Xiquan and others invented the T-shaped split Hopkinson torsion bar, which almost overcomes all the disadvantages of the pre-energy storage torsion bar. However, due to structural reasons, complex bending waves are inevitably generated in the conversion device, which are difficult to eliminate and will be transmitted to the torsion incident rod. In addition, for torsion bars with large diameters (such as 1000mm), it takes a long time for the wave to propagate on the cross section of the rod. At the same time, the wave has spread along the axial direction, resulting in the fact that the rising edge of the torsion incident wave cannot be steep, which affects the improvement of the experimental strain rate.

[0007] In 2015, Fang Qin and others 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 problem that the rising edge of the torsion incident wave cannot be steep due to the large cross section of the rod (tube). However, since the flywheel contacts the end face of the incident rod through axial movement, the torque transmission requires friction between the surfaces. Since it takes a certain amount of time from the beginning of contact to full contact (no relative movement between the surfaces), the rising edge of the torsion pulse generated by this method is too long and cannot meet the requirements of the conventional Hopkinson torsion bar. Summary of the invention:

[0008] In order to overcome the deficiencies in the prior art, the present invention provides an electromechanical combined loading type Hopkinson torsion bar.

[0009] The present invention solves the technical problem by adopting the following technical solution:

[0010] An electromechanical combined loading Hopkinson torsion bar comprises: a support part, the support part comprises a base support, and a sleeper is arranged on the base support;

[0011] A guide rail, wherein the guide rail is mounted on a sleeper and a central bracket is provided on the guide rail;

[0012] Twist the incident rod;

[0013] Twist the transmission rod;

[0014] Wherein, the torsion incident rod and the torsion transmission rod are fixed on the guide rail through a central bracket arranged on the guide rail, and a test piece assembly is placed between the torsion incident rod and the torsion transmission rod;

[0015] A power system is provided at one end of the guide rail close to the torsion incident rod, specifically: an accumulator, an axial strong force docking system, a rotational power loading and control system, a rotational energy storage and release system, a circumferential rapid loading system and a torsion pulse shaper are connected together in sequence, and the torsion pulse shaper is connected to the torsion incident rod.

[0016] Preferably, the axial strong force docking system, the rotational power loading and control system and the rotational energy storage and release system are rigidly connected together.

[0017] Preferably, adjustment feet are provided under the base support.

[0018] Preferably, the axial strong docking 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 at the bottom, and are arranged on the guide rails through the adjustable bases.

[0019] Preferably, the circumferential rapid loading system comprises a torsion pulse output shaft and a shaftless inner disc,

[0020] The shaftless inner collision disc is a concave disc;

[0021] One end of the torsional pulse output shaft is provided with an externally protruding fork, and a shaftless internal collision disc is suspended and supported on the outer periphery of the torsional pulse output shaft. The shaftless internal collision disc rotates to circumferentially collide with the externally protruding fork of the torsional pulse output shaft, thereby forming a dynamic torsional pulse in the torsional pulse output shaft.

[0022] Preferably, the circumferential rapid loading system also includes a rotational residual kinetic energy absorption system.

[0023] Preferably, the torsional pulse shaper is a thin-walled cylindrical structure with flanges at both ends, which shapes the torsional pulse in the torsional pulse output shaft into the torsional pulse required for the test.

[0024] Compared with the prior art, the present invention has the following technical effects:

[0025] In the present invention, the shaftless inner impact disk rotates and impacts the torsion pulse output shaft, generating a transient torsion (shear stress) pulse in the torsion pulse output shaft, and directly applies a required pulse torque to the incident rod end through a pulse shaper, thereby making up for many shortcomings 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 Hopkinson torsion bar device, greatly reducing the experimental difficulty and greatly improving the experimental efficiency.

[0026] Other features and advantages of the present invention will be described in detail in the following detailed description. Description of the drawings:

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 A front view of the electromechanical combined loading Hopkinson torsion bar provided by the present invention, Figure 2 for Figure 1 Sectional view of the CC section;

[0029] Explanation of the numbers in the figure: 1. Accumulator, 2. Axial strong force docking system, 3. Rotational power loading and control system, 4. Rotational energy storage and release system, 5. Circumferential rapid loading system, 5-1 Rotational residual kinetic energy absorption system, 5-2 Torsion pulse output shaft, 5-3 Shaftless internal collision disk, 6. Torsion pulse shaper, 7. Torsion incident rod, 8. Center bracket, 9. Test piece assembly, 10. Torsion transmission rod, 11. Guide rail, 12. Sleeper, 13. Foundation bracket, 14. Adjustment foot, 15. Adjustable base 1, 16. Adjustable base 2, 17. Adjustable base 3.

[0030] Specific implementation structure:

[0031] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0032] like Figure 1-2A mechatronic combined loading Hopkinson torsion bar comprises 1. an accumulator, 2. an axial strong docking system, 3. a rotational power loading and control system, 4. a rotational energy storage and release system, 5. a circumferential rapid loading system, 6. a torsional pulse shaper, 7. a torsional incident rod, 8. a central support, 9. a specimen assembly, 10. a torsional transmission rod, 11. a guide rail, 12. a sleeper, 13. a basic support, 14. an adjustment foot, 15. an adjustable base 1, 16. an adjustable base 2, 17. an adjustable base 3.

[0033] The circumferential rapid loading system comprises 5-1 a rotational residual kinetic energy absorption system, 5-2 a torsional pulse output shaft, and 5-3 a shaftless inner collision disc;

[0034] The shaftless inner collision disc is a concave disc;

[0035] One end of the torsional pulse output shaft is provided with an externally protruding fork, and a shaftless internal collision disc is suspended and supported on the outer periphery of the torsional pulse output shaft. The shaftless internal collision disc rotates to circumferentially collide with the externally protruding fork of the torsional pulse output shaft, thereby forming a dynamic torsional pulse in the torsional pulse output shaft.

[0036] The torsional pulse shaper is a thin-walled cylindrical structure with flanges at both ends, which shapes the torsional pulse in the torsional pulse output shaft into the torsional pulse required for the test.

[0037] First, a certain pressure of high-pressure gas is filled in the accumulator, ready to be released at any time to push the assembly of components 2, 3, and 4. Electricity starts the rotary power loading and control system 3, and drives the rotary energy storage and release system 4 to rotate at high speed to store a certain amount of rotational kinetic energy. Then the high-pressure gas in the accumulator 1 is released to push the assembly of components 2, 3, and 4 to move rapidly axially, hit and hook the shaftless inner collision disc 5-3, and drive it to rotate at the same speed as the rotary energy storage and release system 4. After the shaftless inner collision disc 5-3 rotates a certain angle, it hits the torsional pulse output shaft 5-2, generating a dynamic torsional pulse in the latter. The torsional pulse is shaped by the torsional pulse shaper 6 and enters the torsional incident rod 7. The shaped pulse propagates in the incident rod toward the end where the specimen is located, and reflection and transmission occur at the specimen. The reflected signal forms a reflected pulse in the incident rod and propagates 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. The incident pulse, reflected pulse and transmitted pulse are recorded, and the dynamic shear stress, dynamic shear strain and strain rate of the specimen 5 can be obtained according to the one-dimensional stress wave theory, and the shear stress-strain curve of the specimen material at a certain strain rate can be obtained.

[0038] The torsional pulse output shaft 5-2 is blocked and stops rotating after rotating a certain angle. At this time, the rotational energy storage and release system 4 is disengaged from the rotational power loading and control system 3, and the rotational energy storage and release system 4 is in a forced braking state; the rotating parts in the rotational power loading and control system 3 enter a free rotation state, and finally slowly stop rotating under the action of the friction torque.

[0039] The invention makes up for many shortcomings of the existing pre-energy storage type separated Hopkinson torsion bar, the explosive driven Hopkinson torsion bar device, the T-shaped Hopkinson torsion bar device and the flywheel type Hopkinson torsion bar device, greatly reduces the experimental difficulty and greatly improves the experimental efficiency.

[0040] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An electromechanical combined loading Hopkinson torsion bar, characterized in that: It comprises a support part, wherein the support part comprises a basic support, and a sleeper is arranged on the basic support; A guide rail, wherein the guide rail is mounted on a sleeper and a central bracket is provided on the guide rail; Twist the incident rod; Twist the transmission rod; Wherein, the torsion incident rod and the torsion transmission rod are fixed on the guide rail through a central bracket arranged on the guide rail, and a test piece assembly is placed between the torsion incident rod and the torsion transmission rod; The end of the guide rail close to the torsion incident rod is provided with a power system, specifically: an accumulator, an axial strong docking system, a rotational power loading and control system, a rotational energy storage and release system, a circumferential rapid loading system and a torsion pulse shaper, which are arranged in sequence along the axis, and the torsion pulse shaper is connected to the torsion incident rod; The axial strong docking system, the rotary power loading and control system and the rotary energy storage and release system are rigidly connected together along the axis; The circumferential rapid loading system comprises a torsion pulse output shaft and a shaftless inner collision disc; The shaftless inner collision disc is a concave disc; One end of the torsion pulse output shaft has an externally protruding fork, and the shaftless inner-collision disc is suspended and supported on the outer periphery of the torsion pulse output shaft. The shaftless inner-collision disc rotates to circumferentially collide with the externally protruding fork of the torsion pulse output shaft, thereby forming a dynamic torsion pulse in the torsion pulse output shaft; The torsional pulse shaper is a thin-walled cylindrical structure with flanges at both ends, which shapes the torsional pulse in the torsional pulse output shaft into the torsional pulse required for the test; First, a certain pressure of high-pressure gas is charged in the accumulator, which is ready to be released at any time to promote the axial strong docking system, the rotary power loading and control system and the circumferential rapid loading system. The rotary power loading and control system is electrically started, and the rotary energy storage and release system is driven to perform high-speed rotational motion to store a certain amount of rotational kinetic energy. Then, the high-pressure gas in the accumulator is released to promote the axial strong docking system, the rotary power loading and control system and the circumferential rapid loading system to perform rapid axial movement, impact and hook the shaftless inner collision disc, and drive it to rotate at the same speed as the rotary energy storage and release system. After the shaftless inner collision disc rotates a certain angle, The torsion pulse output shaft is impacted to generate a dynamic torsion pulse in the latter. The torsion pulse is shaped by the torsion pulse shaper and enters the torsion incident rod. The shaped pulse propagates in the incident rod toward the end where the specimen is located, and is reflected and transmitted at the specimen. The reflected signal forms a reflected pulse in the incident rod and propagates toward the loading end of the incident rod; the transmitted signal forms a transmitted pulse and propagates toward the free end of the transmission rod. The incident pulse, reflected pulse and transmitted pulse are recorded, and the dynamic shear stress, dynamic shear strain and strain rate of the specimen are obtained according to the one-dimensional stress wave theory, and the shear stress-strain curve of the specimen material at a certain strain rate is obtained; The torsional pulse output shaft is blocked and stops rotating after rotating a certain angle. At this time, the rotational energy storage and release system is disengaged from the rotational power loading and control system, and the rotational energy storage and release system is in a forced braking state; the rotating parts in the rotational power loading and control system enter a free rotation state, and finally slowly stop rotating under the action of the friction torque.

2. According to the electromechanical combined loading Hopkinson torsion bar as claimed in claim 1, characterized in that: Adjustment feet are arranged under the basic support.

3. According to the electromechanical combined loading Hopkinson torsion bar as claimed in claim 1, it is characterized by: The axial strong docking 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 at the bottom, and are arranged on the guide rails through the adjustable bases.

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