Static and dynamic dual-mode torsion test clamp with variable mechanical limit

Abstract

The invention provides a variable mechanical limit static and dynamic dual-mode torsion test fixture, which comprises at least one fixture body, the fixture body comprises a base and a motion torsion device, the base comprises a bottom plate and two side plates, and the bottom plate and the two side plates define a test piece channel for accommodating a test piece; the motion torsion device comprises a shell, a torsion chuck and a servo motor, the torsion chuck is movably mounted in the shell and used for fixing a test piece, and the servo motor is used for driving the torsion chuck to rotate; and the motion torsion device can slide in the test piece channel. The motion torsion device is arranged in the base in a sliding manner, and the mechanical limit of the motion torsion device can be adjusted in the horizontal direction, so that the fixture adapts to slender strip-shaped test pieces with different lengths, the universality of the fixture is remarkably improved, and the application range of the fixture is remarkably widened; a plurality of independent motion torsion devices can be arranged on the base at the same time, the same or different torsion angles and cyclic loading modes can be applied to different sections of the same test piece, and the experiment function of the clamp is expanded.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of torsion test technology and material mechanics performance test technology, in particular to a static and dynamic dual-mode torsion test fixture with variable mechanical limiting for an elongated test piece. BACKGROUND

[0002] In the field of material science and structural engineering, the torsion performance test of an elongated strip-shaped material is an important means to evaluate key mechanical parameters such as torsional strength, torsional stiffness, and fatigue life. Currently, conventional torsion test fixtures are mainly divided into two categories: One category is a simple mechanical chuck. This type of chuck fixes the test piece through bolts or a pressing mechanism. Although this type of fixture is simple in structure, it has a significant defect. After applying a torsional force to the test piece, the test piece is prone to elastic rebound once the external force is removed, and it cannot maintain its torsional state for a long time and stably, which brings great inconvenience to the subsequent observation, measurement, and multi-field and multi-condition loading experiment of the test piece.

[0003] The other category is a fixture integrated with a torsion testing machine. Although this type of fixture can achieve torsional loading function, it is often complex in structure and high in cost. This type of fixture has fixed limiting and is only suitable for testing standard length torsion samples, and it is difficult to accurately and slowly control the cyclic torsional loading process. In particular, in complex experiments with external equipment of multi-field excitation, its flexibility and applicability are insufficient. Therefore, there is an urgent need for an elongated test piece fixture that can maintain the torsional state of the test piece for a long time and achieve cyclic loading. SUMMARY

[0004] In view of the above deficiencies of the prior art, the present application aims to provide a static and dynamic dual-mode torsion test fixture with variable mechanical limiting, which solves the problems of the prior art that the torsion test fixture is either complex in structure or cannot maintain the torsional state of the test piece, and provides a multifunctional and high-reliability fixture that can achieve automatic cyclic loading through a servo motor and absolute angle locking through a manual mechanical device.

[0005] To achieve the above object and other related objects, the present application provides a variable mechanical limit static and dynamic dual-mode torsion test fixture, comprising at least one fixture body, the fixture body comprising a base and a motion torsion device; the base comprises a bottom plate and two side plates, the bottom plate and the two side plates surround a test piece channel for accommodating a test piece, the inner wall of the side plate is provided with a first sliding rail along the length direction; the motion torsion device comprises a shell, a torsion chuck and a servo motor, the torsion chuck is movably installed in the shell, the torsion chuck is used for fixing the test piece, and the servo motor is used for driving the torsion chuck to rotate; the outer wall of the shell is provided with a first sliding groove for sliding connection with the first sliding rail, so that the motion torsion device can slide in the test piece channel; the motion torsion device and the base are further provided with a positioning device for controlling the relative position of the motion torsion device in the test piece channel.

[0006] As a preferred embodiment of the present application, the torsion chuck comprises an inner cylindrical body and an outer transmission ring gear, a first ring groove is arranged between the inner cylindrical body and the outer transmission ring gear, a first pressure head assembly for clamping the test piece is arranged in the inner cylindrical body, and the output end of the servo motor is provided with a power gear engaged with the outer transmission ring gear Further, a through hole is formed in the shell, the inner cylindrical body of the torsion chuck is rotatably arranged in the through hole, and the outer periphery of the through hole is provided with a second ring groove for accommodating the outer transmission ring gear; the shell is further provided with an annular cover plate at the opening surface of the second ring groove, which is used to constrain the torsion chuck in the shell so that it can only rotate.

[0007] Further, the number of teeth of the transmission gear is greater than the number of teeth of the power gear.

[0008] Further, the first pressure head assembly comprises an upper trapezoidal pressure head and a lower trapezoidal pressure head, a through trapezoidal groove is formed in the inner cylindrical body, the upper trapezoidal pressure head and the lower trapezoidal pressure head are movably arranged in the trapezoidal groove, the upper inclined surface of the trapezoidal groove is matched with the wedge surface of the upper trapezoidal pressure head, and the lower inclined surface of the trapezoidal groove is matched with the wedge surface of the lower trapezoidal pressure head; the inner cylindrical body is further provided with a fastening screw for pressing the upper trapezoidal pressure head and the lower trapezoidal pressure head in the horizontal direction.

[0009] Further, one end of the trapezoidal groove with a larger opening is provided with a limiting part, a first threaded hole is formed in the limiting part, and the fastening screw is screwed into the first threaded hole.

[0010] As a preferred embodiment of the present application, the shell is further provided with a limiting device, the limiting device comprises a limiting pin which can be inserted into or withdrawn from the second ring groove; when the test piece is twisted to a set angle, the limiting pin can be clamped into the second ring groove, and the rotating state of the outer transmission ring gear is mechanically locked.

[0011] Further, the limiting device further comprises a clamping pin rotating shaft and a clamping pin control piece, the clamping pin is hinged on the shell through the clamping pin rotating shaft, and the insertion state and the withdrawal state of the clamping pin are defined by the actuation position of the clamping pin control piece.

[0012] Further, the clamping pin control piece and the clamping pin are located at two ends of the clamping pin rotating shaft respectively, and the included angle between the two is obtuse.

[0013] As a preferred embodiment of the present application, a second pressure head assembly is arranged at one end of the base for fixing one end of the test piece.

[0014] Further, the second pressure head assembly comprises a pressure head platform, one end of the base is provided with a baffle, the baffle is provided with a mounting groove matched with the pressure head platform, the pressure head platform and the mounting groove are in sliding connection, and a fastening screw is further arranged between the pressure head platform and the baffle to fix the positions of the two.

[0015] Further, second sliding rails are arranged at two sides of the pressure head platform, second sliding grooves matched with the second sliding rails are arranged at two sides of the mounting groove, and the second sliding grooves are arranged in the vertical direction.

[0016] Further, lugs protruding from two sides are arranged on the top of the pressure head platform, second threaded holes are arranged in the lugs, a corresponding third threaded hole is arranged on the top of the baffle, and the fastening screw is locked into the threaded holes in sequence to fix the positions of the pressure head platform and the baffle.

[0017] As a preferred embodiment of the present application, the positioning device is a ball screw sliding table structure, the positioning device comprises a ball screw and a ball screw nut, the ball screw is rotatably arranged on the base and arranged in the length direction, the ball screw nut is fixed in the shell, and the ball screw and the ball screw nut are in threaded connection.

[0018] Further, a handle or a motor is connected to the end of the ball screw.

[0019] Further, at least two fixing seats are fixed on the bottom plate of the base, and the ball screw is rotatably connected with the fixing seats.

[0020] As a preferred embodiment of the present application, two or more motion torsion devices are arranged in the base.

[0021] As a preferred embodiment of the present application, the variable mechanical limiting static and dynamic dual-mode torsion test clamp comprises two or more arrayed clamp bodies.

[0022] As described above, the variable mechanical limiting static and dynamic dual-mode torsion test clamp of the present application has the following beneficial effects: 1. The application can adjust the mechanical limit in the horizontal direction by sliding the motion torsion device in the base, so as to adapt to the elongated strip-shaped test piece of different lengths, thereby significantly improving the universality and application range of the clamp; and with the help of the positioning device, high-precision position control of the motion torsion device in the test piece channel can be realized, which not only can avoid the torsion of the test piece driving the motion torsion device to slip, but also can effectively improve the position adjustment accuracy.

[0023] 2. The application can drive the torsion chuck to drive the test piece to reciprocate at a constant angular velocity through the external control system to accurately control the forward and reverse motion of the servo motor, so as to realize slow, programmable cyclic loading of the test piece, and is suitable for dynamic mechanical testing of material torsional fatigue performance.

[0024] 3. The application can realize the locking of the test piece torsion state by manually operating the limiting device and inserting the limiting pin into the second circular ring groove to mechanically lock the transmission gear of the torsion chuck. The locking mode is rigid constraint, which does not depend on the continuous power supply of the servo motor, and can realize long-term, stable and reliable maintenance of the test piece torsion state, and meets the needs of static observation and long-time experiment.

[0025] 4. The application combines the two locking modes of servo motor self-locking and manual mechanical limiting. In the working condition that requires absolute safety guarantee, the two locking modes can be used at the same time to form double redundant constraint, which greatly improves the reliability and safety of the torsion state maintenance, and effectively prevents the experiment failure caused by accidental power failure or motor lock loss.

[0026] 5. The application can set multiple independent motion torsion devices on the base, and can respectively apply the same or different torsion angles and cyclic loading modes to different sections of the same test piece, so as to simulate and realize complex, non-uniform and regional torsion loading working conditions, and expand the experimental function of the clamp. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a structure schematic view of the variable mechanical limiting static and dynamic dual-mode torsion test clamp disclosed in embodiment 1 of the application.

[0028] Figure 2 It is a sectional view schematic view of the variable mechanical limiting static and dynamic dual-mode torsion test clamp disclosed in embodiment 1 of the application.

[0029] Figure 3 It is a structure schematic view of the motion torsion device disclosed in embodiment 1 of the application.

[0030] Figure 4 It is a disassembly schematic view of the motion torsion device disclosed in embodiment 1 of the application.

[0031] Figure 5Structure diagram of the torsion chuck disclosed in embodiment 1 of the present application.

[0032] Figure 6 Sectional view diagram of the torsion chuck disclosed in embodiment 1 of the present application.

[0033] Figure 7 Structure diagram of the limiting device disclosed in embodiment 1 of the present application.

[0034] Figure 8 Structure diagram of the base and the second pressure head assembly disclosed in embodiment 1 of the present application.

[0035] Figure 9 Structure diagram of the variable mechanical limiting static and dynamic dual-mode torsion test fixture disclosed in embodiment 2 of the present application.

[0036] Figure 10 Structure diagram of the variable mechanical limiting static and dynamic dual-mode torsion test fixture disclosed in embodiment 3 of the present application.

[0037] Element number explanation 100, base; 110, bottom plate; 120, side plate; 121, first sliding rail; 130, test piece channel; 200, motion torsion device; 210, shell; 211, first sliding groove; 212, through hole; 213, second circular ring groove; 214, mounting cavity; 220, torsion chuck; 221, inner side cylinder; 222, outer side transmission circular ring gear; 223, first circular ring groove; 224, trapezoidal groove; 225, limiting part; 226, first threaded hole; 230, annular cover plate; 240, servo motor; 241, power gear; 250, first pressure head assembly; 251, upper trapezoidal pressure head; 252, lower trapezoidal pressure head; 300, second pressure head assembly; 310, baffle; 311, mounting groove; 312, second sliding groove; 313, third threaded hole; 320, pressure head platform; 321, second sliding rail; 322, lug; 323, second threaded hole; 400, limiting device; 410, limiting needle; 420, needle rotation shaft; 430, needle control piece; 500, positioning device; 510, ball screw; 520, handle; 530, fixed seat; 600, test piece. DETAILED DESCRIPTION

[0038] The present application will be described in greater detail by way of specific embodiments, and those skilled in the art will easily understand other advantages and effects of the present application from the contents disclosed in the specification. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0039] Embodiment 1 Please refer to Figures 1-8The embodiment provides a variable mechanical limit static and dynamic dual-mode torsion test fixture.

[0040] The base 100 is in the shape of a "V" as a whole, comprises a bottom plate 110 and two side plates 120, a test piece channel 130 for accommodating the test piece 600 is formed between the bottom plate 110 and the two side plates 120, and a first sliding rail 121 is arranged on the inner wall of each side plate 120 along the length direction of the side plate 120; the second pressure head assembly 300 is arranged at one end of the base 100 and used for fixing one end of the test piece 600; the motion torsion device 200 is slidingly arranged in the test piece channel 130 of the base 100 and used for fixing and twisting the other end of the test piece 600; the positioning device 500 is used for controlling the relative position of the motion torsion device 200 in the test piece channel 130; and the limiting device 400 is used for mechanically locking the torsion state.

[0041] Reference Figures 3-4 The motion torsion device 200 comprises a shell 210, a torsion chuck 220 and a servo motor 240; first sliding grooves 211 are formed in the two side walls of the shell 210 and used for slidingly connecting with the first sliding rails 121, so that the motion torsion device 200 can slide in the test piece channel 130, and the position of the motion torsion device 200 can be adjusted according to the length of the test piece 600. The torsion chuck 220 is rotatably installed in the shell 210, the torsion chuck 220 is used for fixing the test piece 600, and the servo motor 240 is used for driving the torsion chuck 220 to rotate.

[0042] Reference Figures 5-6 The torsion chuck 220 comprises an inner cylindrical body 221 and an outer transmission ring gear 222, a first ring groove 223 is arranged between the inner cylindrical body 221 and the outer transmission ring gear 222, a first pressure head assembly 250 for clamping the test piece 600 is arranged in the inner cylindrical body 221, a power gear 241 engaged with the outer transmission ring gear 222 is arranged at the output end of the servo motor 240, and the servo motor 240 drives the transmission gear through the power gear 241, so that the rotation of the torsion chuck 220 is realized.

[0043] Specifically, a through hole 212 is formed in the shell 210, the inner cylindrical body 221 of the torsion chuck 220 is in clearance fit with the through hole 212 and is rotatably arranged in the through hole 212, a second ring groove 213 for accommodating the outer transmission ring gear 222 is arranged on the outer periphery of the through hole 212, and a ring-shaped cover plate 230 is further arranged on the opening surface of the second ring groove 213 of the shell 210 and used for restraining the torsion chuck 220 in the shell 210, so that the torsion chuck 220 can only rotate.

[0044] Reference Figure 6In the cross-sectional view, the first pressure head assembly 250 includes an upper trapezoidal pressure head 251 and a lower trapezoidal pressure head 252, and a trapezoidal groove 224 is formed through the inner cylindrical body 221, the upper and lower surfaces of the trapezoidal groove 224 are respectively inclined surfaces; the upper trapezoidal pressure head 251 and the lower trapezoidal pressure head 252 are movably arranged in the trapezoidal groove 224, and the upper inclined surface of the trapezoidal groove 224 is matched with the wedge surface of the upper trapezoidal pressure head 251, and the lower inclined surface of the trapezoidal groove 224 is matched with the wedge surface of the lower trapezoidal pressure head 252. The smaller opening end of the trapezoidal groove 224 is directed to the direction of the second pressure head assembly 300, and the larger opening end of the trapezoidal groove 224 is directed to the outside of the base 100, and the test piece 600 passes through the trapezoidal groove 224 and is clamped between the upper and lower trapezoidal pressure heads. The larger opening end of the trapezoidal groove 224 is provided with a limiting portion 225, a first threaded hole 226 is formed in the limiting portion 225, and a fastening screw is screwed into the first threaded hole 226, which is used to tightly press the upper trapezoidal pressure head 251 and the lower trapezoidal pressure head 252, so as to realize the clamping of the test piece 600 by matching the wedge surfaces of the upper trapezoidal pressure head 251 and the lower trapezoidal pressure head 252.

[0045] Further, the number of teeth of the outer transmission ring gear 222 is about 2-8 times the number of teeth of the power gear 241. By setting the number of teeth of the outer transmission ring gear 222 to be greater than the number of teeth of the power gear 241, the rotation accuracy of the torsion chuck 220 can be improved, and the torsion speed and the torsion angle can be more accurately controlled, so as to simulate and realize more complex torsion loading conditions, and expand the experimental functions of the clamp.

[0046] Reference Figure 4 And 7 The housing 210 is further provided with a limiting device 400, the limiting device 400 includes a limiting pin 410, a pin rotating shaft 420 and a pin control piece 430, the limiting pin 410 and the pin control piece 430 are respectively located at two ends of the pin rotating shaft 420, the housing 210 is provided with a mounting cavity 214 communicating with the second ring groove 213, and the limiting pin 410 is hinged in the mounting cavity 214 through the pin rotating shaft 420; the limiting pin 410 can be inserted into or withdrawn from the second ring groove 213 by rotating the limiting pin 410, and the insertion state and the withdrawal state of the limiting pin 410 are limited by the position of the pin control piece 430. When the test piece 600 is twisted to a set angle, the limiting pin 410 can be clamped into the second ring groove 213, and the rotation state of the outer transmission ring gear 222 is mechanically locked. The included angle between the pin control piece 430 and the limiting pin 410 is obtuse.

[0047] Reference Figure 8The second pressure head assembly 300 comprises a pressure head platform 320, and two second sliding rails 321 are arranged on two sides of the pressure head platform 320. One end of the base 100 is provided with a baffle 310, the baffle 310 is provided with a mounting groove 311 matched with the pressure head platform 320, and two second sliding grooves 312 matched with the second sliding rails 321 are arranged on two sides of the mounting groove 311 and arranged in the vertical direction. The pressure head platform 320 and the mounting groove 311 are connected through the sliding rail and the sliding groove, the test piece 600 is placed in the mounting groove 311, and the test piece 600 is pressed tightly through the pressure head platform 320. The pressure head platform 320 and the baffle 310 are further provided with a fastening screw for fixing the positions of the pressure head platform 320 and the baffle 310.

[0048] Specifically, the top of the pressure head platform 320 is provided with protruding lugs 322 on two sides, the lugs 322 are provided with second threaded holes 323, the top of the baffle 310 is provided with corresponding third threaded holes 313, and the fastening screw is locked into the two threaded holes in sequence to fix the positions of the pressure head platform 320 and the baffle 310, so as to clamp the test piece 600.

[0049] Further, the bottom surface of the pressure head platform 320 is an arc surface protruding downward.

[0050] Reference Figure 1 The positioning device 500 is a ball screw sliding table structure, and comprises a ball screw 510 and a screw nut. The ball screw 510 is rotationally arranged on the base 100 and arranged in the length direction, the screw nut is fixed in the shell 210, and the ball screw 510 is threadedly matched with the screw nut. The end of the ball screw 510 is connected with a handle 520 or a motor, the ball screw 510 can be driven to rotate, the screw nut and the shell 210 fixedly connected with the screw nut can move axially along the ball screw 510, so as to realize the position adjustment of the motion and torsion device 200. When the test piece 600 is twisted, the cooperation of the ball screw 510 and the screw nut can avoid the sliding of the motion and torsion device 200 caused by the twisting of the test piece 600.

[0051] Further, at least two fixing seats 530 are fixed on the bottom plate 110 of the base 100, and the two ends of the ball screw 510 are rotationally connected with the corresponding fixing seats 530. The fixing seat 530 provides stable support for the ball screw 510, ensures the coaxiality and stability of the ball screw 510 during rotation, and avoids the influence of the position accuracy of the motion and torsion device 200 caused by the shaking of the ball screw 510.

[0052] Embodiment 2 Reference Figure 9 The embodiment provides a static and dynamic dual-mode torsion test clamp with variable mechanical limiting, and compared with the embodiment 1, the difference is that three clamp bodies are arranged side by side, and the structure of each clamp body is consistent with that in the embodiment 1.

[0053] Embodiment 3 Please refer to Figure 10 The embodiment provides a variable mechanical limit static and dynamic dual-mode torsion test fixture, which comprises a fixture body, and compared with embodiment 1, the difference only lies in that at least two motion torsion devices 200 are arranged in the base 100.

[0054] Embodiment 4 Static holding of fixed torsion angle, this mode is used for experiments that need to maintain a specific torsion angle of a test piece for a long time, and the operation process is as follows: Clamping test piece: the elongated test piece 600 is horizontally clamped through the test piece channel 130, one end of the test piece 600 is fixed in the second pressure head assembly 300, and the other end or a specified position of the test piece 600 is arranged in the torsion chuck 220 of the motion torsion device 200, and the test piece 600 is clamped in the axial direction by driving the upper and lower trapezoidal pressure heads by tightening the fastening screws, so that the test piece 600 is prevented from slipping during the torsion process.

[0055] Applying torsion: the servo motor 240 is started, the torsion chuck 220 is rotated by program control, and the test piece 600 is twisted to a specific angle required.

[0056] Mechanical locking: when the angle reaches the set value, the operator manually drives the needle control piece 430, drives the limiting needle 410 to rotate around the needle rotating shaft 420, inserts the head of the limiting needle 410 into the second circular groove 213, prevents the rotation of the outer transmission circular gear 222, and mechanically locks the torsion state of the test piece 600.

[0057] Long-term holding: in this state, the power supply of the servo motor 240 can be safely turned off, and long-term static experiments can be carried out. Since it is mechanically locked, the torsion angle will not be lost due to power failure or servo motor 240 lock loss.

[0058] Embodiment 5 Torsion cyclic loading, this mode is used for simulating the fatigue performance test of materials under alternating torsion load, and the operation process is as follows: Clamping test piece: same as embodiment 4.

[0059] Setting cycle program: the servo motor is programmed through an external control system, and parameters such as clockwise torsion angle (θ+), counterclockwise torsion angle (θ-), angular velocity (ω), cycle number (N) and pause time (t) are set.

[0060] Performing cyclic loading: start the servo motor, which will automatically reciprocate according to the preset program. For example, rotate clockwise at a constant angular velocity ω to +θ degrees, pause for t seconds, rotate counterclockwise at the same angular velocity to -θ degrees, pause for t seconds, and so on for N times. During the entire process, the limit pin is in the withdrawn state and does not interfere with the free rotation of the torsion chuck.

[0061] End of loading: after the completion of cyclic loading, the servo motor stops working, and the test piece returns to the initial state or stays at the final angle.

[0062] Example 6 This embodiment provides a variable mechanical limit static and dynamic dual-mode torsion test fixture. Compared with example 1, the difference is only that a torque sensor is arranged on the servo motor or the torsion chuck, which is used to measure the torque (T) of the test piece. The torque sensor is selected from the existing torque sensors on the market, including contact and non-contact torque sensors.

[0063] Example 7 This embodiment provides a variable mechanical limit static and dynamic dual-mode torsion test fixture. Compared with example 6, the difference is only that an angle sensor is arranged on the servo motor or the torsion chuck, which is used to measure the torque angle (φ) of the test piece.

[0064] According to the collected torque (T), as well as the torsion angle (φ) and the test piece parameters (such as the effective length L, the polar moment of inertia Ip), the shear modulus (G), the torsional strength and other material properties can be calculated, which is convenient for analyzing the material elastic stage, the yield stage and the ultimate bearing performance.

[0065] In summary, the motion torsion device is slidably arranged in the base, the mechanical limit can be adjusted in the horizontal direction, so as to adapt to the elongated strip-shaped test piece of different lengths, thereby significantly improving the universality and application range of the fixture. Multiple independent motion torsion devices can be arranged on the base at the same time, different sections of the same test piece can be subjected to the same or different torsion angles and cyclic loading modes, thereby simulating and realizing complex and non-uniform regional torsion loading conditions, and expanding the experimental function of the fixture. Therefore, the present application effectively overcomes the shortcomings of the prior art and has high industrial utilization value.

[0066] In the specification, the terms such as "up", "down", "left", "right", "front", "back", "middle" and "one" are only for the convenience of clear description, and are not used to limit the scope of the application. The change or adjustment of the relative relationship is also considered as the implementation scope of the application without substantial change in technical content.

[0067] The above embodiments merely illustrate the principles of the application and its efficacy, and are not intended to limit the application. All equivalent modifications or changes made by those with ordinary knowledge in the art without departing from the spirit and technical ideas disclosed in the application shall be covered by the claims of the application.

Claims

1. A variable mechanically limited static-dynamic dual mode torsion test fixture, characterized in that, The device comprises at least one clamp body, which comprises a base and a motion twisting device, The base comprises a bottom plate and two side plates, which enclose a specimen channel for accommodating a specimen, and the inner wall of the side plate is provided with a first sliding rail along the length direction thereof; The motion twisting device comprises a shell, a twisting chuck and a servo motor, the twisting chuck is movably installed in the shell, the twisting chuck is used for fixing the specimen, and the servo motor is used for driving the twisting chuck to rotate; The outer wall of the shell is provided with a first sliding groove for sliding connection with the first sliding rail, so that the motion twisting device can slide in the specimen channel.

2. The variable mechanically limited static-dynamic bimodular torsion test fixture of claim 1, wherein, The twisting chuck comprises an inner side cylinder and an outer side transmission ring gear, a first ring groove is arranged between the inner side cylinder and the outer side transmission ring gear, a first pressure head assembly for clamping the specimen is arranged in the inner side cylinder, and the output end of the servo motor is provided with a power gear engaged with the outer side transmission ring gear; The shell is internally provided with a through hole, the inner side cylinder of the twisting chuck is rotationally arranged in the through hole, and the outer periphery of the through hole is provided with a second ring groove for accommodating the outer side transmission ring gear; the shell is further provided with an annular cover plate at the opening surface of the second ring groove, for constraining the twisting chuck in the shell.

3. The variable mechanically limited static-dynamic bimodular torsion test fixture of claim 2, wherein, The first pressure head assembly comprises an upper trapezoidal pressure head and a lower trapezoidal pressure head, a trapezoidal groove is arranged in the inner side cylinder, the upper trapezoidal pressure head and the lower trapezoidal pressure head are movably arranged in the trapezoidal groove, the upper inclined surface of the trapezoidal groove is matched with the wedge surface of the upper trapezoidal pressure head, and the lower inclined surface of the trapezoidal groove is matched with the wedge surface of the lower trapezoidal pressure head; the inner side cylinder is further provided with a fastening screw for tightly pressing the upper trapezoidal pressure head and the lower trapezoidal pressure head.

4. The variable mechanically limited static-dynamic bimodular torsion test fixture of claim 2, wherein, The shell is further provided with a limiting device, the limiting device comprises a limiting pin which can be inserted into or withdrawn from the second ring groove; when the specimen is twisted to a set angle, the limiting pin can be clamped into the second ring groove, and the rotation state of the outer side transmission ring gear is mechanically locked.

5. The variable mechanically limited static-dynamic bimodular torsion test fixture of claim 4, wherein, The limiting device further comprises a pin rotation shaft and a pin control piece, the pin control piece and the limiting pin are respectively located at two ends of the pin rotation shaft, the limiting pin is hinged to the shell through the pin rotation shaft, and the insertion state and the withdrawal state of the limiting pin are defined by the actuation position of the pin control piece.

6. The variable mechanically limited static-dynamic bimodular torsion test fixture of claim 1, wherein, A second pressure head assembly is arranged at one end of the base, for fixing one end of the specimen; the second pressure head assembly comprises a pressure head platform, one end of the base is provided with a baffle, the baffle is provided with a mounting groove matched with the pressure head platform, the pressure head platform and the mounting groove are in sliding connection, and a fastening screw is further arranged between the pressure head platform and the baffle to fix the positions of the two.

7. The variable mechanically limited static-dynamic bimodular torsion test fixture of claim 6, wherein, The two sides of the pressure head platform are provided with second sliding rails, the two sides of the mounting groove are provided with second sliding grooves matched with the second sliding rails, and the second sliding grooves are arranged in the vertical direction.

8. The variable mechanically limited static-dynamic bimodular torsion test fixture of claim 6, wherein, The top of the pressure head platform is provided with protruding lugs on two sides, the lugs are provided with second threaded holes, the top of the baffle is provided with corresponding third threaded holes, and the fastening screw is sequentially locked into the threaded holes to fix the positions of the pressure head platform and the baffle.

9. The variable mechanically limited static-dynamic bimodulus torsion test fixture of any of claims 1-8, wherein, The positioning device is a lead screw sliding table structure, comprising a ball screw and a screw nut.

10. The variable mechanically limited static-dynamic bimodular torsion test fixture of claim 9, wherein, The ball screw is rotationally arranged on the base along the length direction, and the screw nut is fixed in the shell, and the ball screw and the screw nut are in threaded cooperation.

Images