110results about "Investigating material ductility" patented technology

A method for identifying a necking limit strain of a metal sheet according to the present invention includes a step (S1) of measuring the distribution of strain in a tensile orthogonal direction in a tensile deformation process of a notch root 5a for two or more types of sheet specimens 1 having a notch geometry 5 in a portion of a sheet edge 3; a step (S3) of obtaining a strain increment ratio of the notch root 5a in the tensile deformation process and a strain gradient in the tensile orthogonal direction; a step (S5) of obtaining necking limit strain at which necking occurs in the notch root 5a based on the strain increment ratio in the tensile deformation process; and a step (S7) of identifying the necking limit strain as a function of the strain gradient from the relation between the necking limit strain obtained for the two or more types of sheet specimens 1 and the strain gradient at that time.

A press forming fracture judgment method according to the present invention acquires a forming limit of a metal sheet which limit is expressed by a relationship between a maximum principal strain and a minimum principal strain of a test piece 100 bulge formed at various bending deformation degrees and a bending deformation degree (P1), and determines presence or absence of fracture generation in a press formed part based on the acquired forming limit of the metal sheet and the maximum principal strain, the minimum principal strain, and the bending deformation degree which are calculated for a press formed part (P3).

The invention discloses a post-welding adjusting and repairing method for an aluminum alloy bracket of a railway vehicle. The post-welding adjusting and repairing method comprises the steps that the first deformation amount of a deformation position is measured; preparing a plurality of first tensile samples, and performing flame heating adjustment at a preset flame heating temperature; performing a tensile test on the first tensile sample; establishing a relationship between the mechanical property and the flame heating temperature, and obtaining a target flame heating temperature; manufacturing a second tensile sample, and performing deformation treatment and mechanical adjustment treatment for preset times; performing a tensile test on the second tensile sample, establishing a relationship between the mechanical property and the times of deformation treatment and mechanical adjustment treatment, and obtaining a target mechanical adjustment time; flame heating adjustment and mechanical adjustment are conducted on the aluminum alloy bracket according to the target flame heating temperature and the target mechanical adjustment frequency; and manufacturing a fatigue sample, carrying out a fatigue test, and evaluating the safety of adjustment and repair. According to the method, flame heating adjustment and mechanical adjustment are combined, welding residual stress can be released, and deformation deviation can be accurately corrected.

The present application relates to the technical field of cotton fiber detection. A kind of intelligent beam fiber strength tester, including cabinet, industrial computer, sliding table module is provided in cabinet, sectional material frame, air cylinder, beam fiber clamping mechanism, stepper motor, lever type pull rod, force sensor, displacement sensor, resistance detection plate, A / D acquisition conversion module;The application method of the tester, steps include: under normal environmental conditions, beam fiber clamping mechanism clamps fiber sample, obtains moisture regain R by resistance moisture regain conversion program conversion;Stepper motor drives lever type pull rod to stretch sample, data is made into the tensile curve F (e) of beam fiber sample-e by industrial computer, and machine learning model predicts the corrected breaking strength value and elongation rate.The present application is simple and reasonable in structure, can realize the quick and accurate measurement of cotton beam fiber breaking strength value and breaking elongation rate under different humidity conditions in normal environment, is high in informatization degree, economic and practical, and improves the accuracy of test result.

The utility model discloses a simple device for drawing a gauge length of an aluminum alloy circular performance sample, which belongs to the technical field of gauge lengths of aluminum alloy samples, solves the problems that the operation is difficult and the marking is easy to generate errors when the gauge length of the aluminum alloy circular performance sample is manually made at present, and comprises a caliper bracket, a sample bracket and a caliper, a sliding rail is arranged on a caliper support bottom plate, vertical groove-shaped caliper support supporting rods are symmetrically arranged on the two sides of the bottom plate, spring columns are arranged at the bottoms in grooves of the caliper support supporting rods, and springs are arranged on the spring columns. A left sample holder supporting rod and a right sample holder supporting rod of the sample bracket are arranged on the slide rail in a sliding manner; the caliper is provided with a fixed measuring claw and a caliper outer measuring claw in a sliding mode, two sides of the caliper are lengthened to be provided with blank caliper bodies, and two ends of the blank caliper bodies are clamped in the caliper support supporting rod grooves in a sliding mode and abut against the tops of the springs. The marking of various scale distances is accurately realized, and the efficiency and the accuracy of marking the scale distances are greatly improved.

The application relates to the technical field of titanium alloy detection, and discloses a titanium alloy wire performance detection method, equipment and system. The method collects real-time force value displacement data of a tensile test and echo signal data of ultrasonic detection, obtains smooth force value displacement data and frequency spectrum characteristic parameters after processing, fuses yield strength and tensile strength with peak frequency and amplitude attenuation rate in a characteristic layer, and constructs a first multi-dimensional characteristic matrix; the method inputs a pre-trained deep confidence network model, predicts mechanical properties such as elongation and hardness value, compares with a preset threshold value, marks unqualified items, and generates a detection report. The method improves the comprehensiveness and accuracy of detection through multi-source data fusion and advanced algorithm processing, realizes efficient evaluation of titanium alloy wire performance, and is suitable for strict detection requirements of titanium alloy wire quality in the fields of aerospace, medical devices and the like.

A method for the assessment of the irradiation embrittlement in a nuclear reactor pressure vessel RPV (10) comprises the steps (a): cutting a specimen (20, 40) from an un-irradiated RPV (10); (b): measuring grain size Dg of each grain (30) on a region (21, 41) of the specimen (20, 40); (c): performing several indentation tests at a temperature on this region; (d) to (g): for each test, calculating for each grain (30) the slip band number density N / Dg from equations; (h): repeating steps (c) to (g) at different temperatures to obtain an un-irradiated curve around the ductile-brittle transition temperature DBTT; (i): submitting specimen (40) to an irradiation dose and repeating steps (b) to (g) at different temperatures to obtain an irradiated curve around the DBTT; (j) and (k): assessing the irradiation embrittlement in the RPV from the ductile-brittle transition shift between the un-irradiated and irradiated curves.

The utility model discloses a steering wheel leather piece stretching, matching and grading automation device which comprises a support. A servo motor, a ball screw, a stretching guide rail, a fixed lower clamp, a first shell and a second shell are installed on the support. A movable table top is slidably connected to the stretching guide rail and sequentially connected with a ball screw and a servo motor. The movable table top is connected with the movable lower clamp and the movable upper clamp assembly, and the movable lower clamp is located under the movable upper clamp assembly. A fixed upper clamp assembly is arranged over the fixed lower clamp and connected with the first shell. A touch screen and a gear indicator lamp are arranged on the shell I; and a warning lamp, an emergency stop knob and a start button are arranged on the shell II. According to the utility model, the elongation value of the leather grafts can be directly measured, whether products meet requirements can be directly judged, the leather grafts meeting the elongation value range are delivered as qualified products, and the leather grafts exceeding the elongation value range are screened out and discarded.

A bond test apparatus (200, 350) comprises: a test tool assembly, the test tool assembly comprising a test tool configured to contact a bond (101) during a bond test; a flexure (80, 380) coupled to the test tool assembly; a displacement sensor (220, 425); and a detectable member (110, 415). One of the detectable member and the displacement sensor is fixed relative to a first end of the flexure and the other is fixed relative to a second end of the flexure. The displacement sensor is not a strain gauge. The displacement sensor is configured to detect a displacement between the displacement sensor and the detectable member, so that the displacement sensor provides a measurement of a displacement of the first end of the flexure relative to the second end of the flexure on application of a force to the flexure. The bond test apparatus comprises a processor configured to receive a displacement signal from the displacement sensor and to determine the force on the flexure using the displacement signal. A cartridge for a bond test apparatus, a method of measuring a force in a bond test apparatus, and a method of measuring the closing force on the jaws of a bond test tool are also provided.

The application discloses a method for setting rolling parameters in a lithium battery pole piece rolling process, which comprises the following steps: based on the process standard of the pole piece appearance and the wave edge height, rolling tests are carried out on the pole piece under different compaction densities to verify the relationship between the elongation of the material area and the elongation of the tab blank area and the tab dispensing area, and the ratio relationship between the elongation of the material area and the elongation of the tab blank area and the tab dispensing area under different compaction densities is determined; different elongation roller coating layer thicknesses and different stretching force values are set on the elongation roller to carry out elongation tests on the pole piece, the relationship between the elongation roller coating layer thickness and the stretching force value and the elongation of the pole piece blank is verified, and a fitting formula and an isogram of the elongation of the pole piece blank and the elongation roller coating layer thickness and the elongation stretching force value are obtained; based on the ratio relationship and the fitting formula, the stretching force value and the elongation roller coating layer thickness under the preset compaction density of the pole piece are calculated, and the isogram is verified.

The present invention provides a technology that enables easy and accurate acquisition of material properties that affect the dimensional accuracy of presses, even within a press line.The method for acquiring material properties of a metal plate for press working involves performing a stretching process on the metal plate, measuring the forming load and die stroke during the stretching process, and measuring the thickness of the metal plate, and then determining the yield stress of the metal plate from the measured forming load, die stroke, and thickness.

To provide a molding limit decision method for metal plate, a molding limit decision system for metal plate and a molding limit decision program for metal plate that can conduct a molding test on a test piece of a metal plate to precisely decide the molding limit of the metal plate.SOLUTION: A molding limit decision method for metal plate includes: constructing a database by molding a metal plate while consecutively photographing a surface of a test piece 101 and measuring strains generated on the surface of the test piece 101 from the start of the molding until fracture and three-dimensional coordinates on the surface of the test piece 101 (S10); setting an evaluation point array along a fracture orthogonal direction orthogonal to a fracture part 103 generated in the test piece 101 and extracting strains or three-dimensional coordinates of the evaluation point array from the database (S20); and calculating a fracture orthogonal-directional gradient of the strains or three-dimensional coordinates of the evaluation point array to decide a molding limit (S30).SELECTED DRAWING: Figure 1

The utility model provides macromolecule waterproof roll ductility detection equipment, and belongs to the technical field of waterproof roll ductility detection. The high polymer waterproof roll ductility detection equipment comprises a processing table, the top of the processing table is provided with a fixed seat, the fixed seat is internally provided with a mounting frame, the mounting frame is internally provided with a hydraulic cylinder, the bottom of the hydraulic cylinder is provided with a limiting plate, a displacement sensor is arranged above the processing table, and the displacement sensor is connected with the hydraulic cylinder. The waterproof roll body, the limiting plate, the limiting fence, the threaded rod, the electric push rod, the pressing block, the hydraulic cylinder and the displacement sensor are matched with one another, the electric push rod is started to drive the pressing block to move downwards, the waterproof roll body can be preliminarily limited, the hydraulic cylinder is started to drive the limiting plate to move downwards, and therefore the waterproof roll body can be fixed. And the displacement sensor is started, so that the waterproof coiled material main body can extend, the waterproof coiled material main body can be prevented from sliding off, and the detection effect is improved.

In a metal plate molding limit determination method according to the present invention: a surface of a test piece 101 is molded while being sequentially images, and a strain on the surface of the test piece 101, which is generated from the start of molding to a point at which fracture occurs, as well as three-dimensional coordinates of the surface of the test piece 101, are measured to construct a database (S10); an evaluation point string is set along a fracture orthogonal direction that is orthogonal to a fractured section 103 generated in the test piece 101, and strain or three-dimensional coordinates in the evaluation point string are extracted from the database (S20); and a fracture orthogonal direction gradient of the strain or the three-dimensional coordinates in the evaluation point string is calculated, and a molding limit is determined (S30).

The invention belongs to the technical field of steel product quality management, and particularly relates to a method and a system for realizing automatic conversion of percentage elongation after fracture of a steel product, which are characterized in that the method is a material test item conversion subprogram in an existing manufacturing system quality management program. Firstly, automatic comparison of sample size codes in a tensile test item is carried out, and when the sample size codes of materials actually subjected to a tensile test are inconsistent with the sample size codes required by a contract, automatic conversion of after-fracture elongation values can be carried out after confirmation of technicians. The method has the beneficial effects that the existing quality system processing logic is perfected by taking the national standard GBT-17600.1 as the benchmark, the automatic conversion of the percentage elongation after fracture as required is realized, the method for automatically judging the quality of a real object and printing a quality guarantee book according to the converted data can be completed, and the occupation of test resources and the material waiting time are greatly reduced.

Methods for determining surface loads, deformations on forming machines and / or the quality of a formed workpiece, in which with at least one forming tool (1) which is force-fitted to a force transmission element (3) of a forming machine or to a table of a forming machine, a mechanical forming force is applied to a workpiece to be processed during a forming process, which causes a surface load and / or a deformation on at least one contact surface (5) between the at least one forming tool (1) and the force transmission element (3) or between the at least one forming tool (1) and the table, and with at least one sensor (4) designed to detect a physical quantity and attached in or on the tool clamping element (2) at a defined position, detects at least one physical quantity in or on the tool clamping element (2) and transmits measurement data of the at least one physical quantity to an electronic evaluation device, and in the electronic evaluation device the surface load on the at least one contact surface (5) and / or the deformation of the at least one contact surface (5) is determined depending on the respective position and the measurement data of the at least one sensor (4) and / or the quality of a workpiece formed in the process is determined; wherein the surface load and / or deformation of the contact surface (5) is / are determined with an evaluation model with which the measurement data of the at least one sensor (4) for a known position of the at least one sensor (4) in or on the tool clamping element (2) is mathematically mapped to the surface load and / or deformation of the contact surface (5) or the quality is determined by the course of at least one recorded physical quantity as a function of time or of the distance traveled during the forming process of at least one forming tool (1).

A fracture determination method in a press forming analysis according to the present invention determines a fracture of a blank in the press forming analysis on the basis of a forming limit diagram, and includes: measuring a distance between each of shell elements of the blank and each of an upper die and a lower die at a tool position where fracture determination is performed (S1); setting a shorter one of the distances to the upper die and the lower die as a tool distance of each of the shell elements (S3); determining that the shell element in which the tool distance is 1 / 2 or less of a sheet thickness is in contact with the tool (S5); and determining presence or absence of the fracture for each of the shell elements by using the forming limit diagram acquired by the Nakajima test for the shell element determined to be in contact with the tool and using the forming limit diagram acquired by the Marciniak test for the shell element not determined to be in contact with the tool (S7).

The invention relates to a testing machine and a testing machine sample chamber (12) for installation in a testing machine (10) for carrying out a material test of a material sample (18) comprising: a sample chamber body (48), a sample holding device (24) for holding the material sample (18) with a first side (26) and a second side (28), a receiving device (32) with a transparent material disc (30), an inlet device (22) for a fluid medium, wherein a sample chamber interior (20) is formed between the material sample (18) and the transparent material disc (30), which can be filled with the fluid. The invention further relates to a testing method for carrying out a material test of a material sample (18), a computer program, a machine learning model and a data processing device for controlling and / or regulating a testing machine (10).

The utility model discloses a PE film thermal ductility detection device, which comprises a rack and an infrared lamp tube, a back plate is arranged above the rear side of the rack, one side of the back plate is rotatably connected with a screw rod and a guide rod which are parallel to each other, a movable block is arranged outside the screw rod and the guide rod, the movable block is in threaded connection with the screw rod and is in sliding connection with the guide rod, and the infrared lamp tube is arranged on the back side of the rack. A first rolling rod is installed on the front side of the back plate, a second rolling rod is installed on the front side of the movable block, notches are formed in the first rolling rod and the second rolling rod, and a pair of clamping pieces is symmetrically installed in the notches through a plurality of sets of springs and used for clamping the movable end of a PE film. After the movable end of the PE film is inserted into the pair of clamping pieces of the rolling bar, the movable end of the PE film is wound for several circles with the rolling bar as the axis, the whole face of the PE film can be bound to the rolling bar, fixation is firmer, the PE film is not prone to falling off in the pulling process, when the two rolling bars are far away from each other and pulled, the whole face of the PE film is stressed more evenly, and the service life of the PE film is prolonged. And the condition of severe local deformation is not easy to cause.

This invention discloses a chemical fiber filament strength testing device and its testing process, comprising a base, a winding unit disposed on one side of the base, and a stretching unit disposed on the other side of the base; the winding unit includes a motor, a winding frame, and a pusher slidably disposed on the winding frame; the stretching unit includes a positioning frame and a sliding frame, and the base is provided with a linear module for driving the sliding frame to move relative to the positioning frame; the motor includes an output shaft cooperating with the winding frame and a lead screw connected to the output shaft, a one-way bearing is provided between the winding frame and the output shaft, and a nut cooperating with the lead screw is provided on the pusher; the output shaft can switch between forward and reverse rotation to realize synchronous rotation of the winding frame and the pusher or to allow the pusher to move laterally relative to the winding frame to push the filament roll onto the stretching unit; this invention mainly solves the problems of dangerous manual operation, inaccurate winding coil count, and low efficiency caused by process separation in the prior art.

To provide a cruciform tensile specimen with slits, when a biaxial tensile test is performed, capable of preventing fracture by reinforcing arms, and manufacturing method of the cruciform tensile specimen with the slits.SOLUTION: A cruciform tensile specimen 1 with slits comprising a square measurement part 3, and arms 5 extending from four sides of the measurement part 3 in a direction of applying a tensile load to the measurement part 3 and including a plurality of slits 7 formed parallel to the extending direction, is used for a biaxial tensile test for applying the tensile load in two orthogonal directions to the measurement part 3 via the four arms 5 to acquire a stress-strain relation under biaxial stress. The cruciform tensile specimen 1 with the slits comprises reinforcing materials 11 joined to cover the respective arms 5 and reinforcing the arms 5, where the reinforcing materials 11 are longer than at least the slits 7 in the direction applying the tensile load in the arms 5, and formed not to close the slits 7 by covering the arms 5.SELECTED DRAWING: Figure 1

The utility model discloses a carbon fiber ductility stretching detector, belongs to the technical field of carbon fiber detection, and aims to solve the problems that a tension detector needs to be driven by a threaded lead screw to move in the vertical direction, so that repeated stretching tests on carbon fibers in a short time are inconvenient, and the detection efficiency is high. The device comprises a base, a tension meter arranged at one end of the base and an adjustable stretching mechanism used for testing the to-be-tested carbon fiber textile, and the adjustable stretching mechanism comprises a vertical movement assembly and a position adjusting assembly; the vertical movement assembly comprises a disc arranged at one end of the tension meter and a motor fixed to the surface of the end, away from the tension meter, of the base. According to the device, the repeated stretching test process is convenient and rapid, so that the efficiency of the detection operation of the carbon fiber textile to be detected is improved, and the applicability of the device is improved.

The utility model belongs to the technical field of asphalt ductility tests, and particularly relates to a constant-temperature tensile test tank of an asphalt ductility instrument, which comprises a main body, a bottom plate, a control device arranged on the main body, a glass cover arranged at the top of the main body, a motor arranged on the outer side of the main body, a test mold arranged on the bottom plate, a side mold arranged on the side surface of the test mold and a lower water tank arranged in the main body, an upper water tank is arranged in the lower water tank, sliding rails are arranged on the two sides of the top of the upper water tank, sliding assemblies are arranged in the sliding rails, and the lower water tank comprises a first interlayer, aerogel, a second interlayer, a third interlayer, a bottom cavity and a heating pipe. Through the first interlayer, the aerogel, the second interlayer, the third interlayer, the bottom cavity and the heating pipe, temperature loss is effectively reduced, the starting frequency of the heating pipe is reduced, the energy-saving effect is achieved, through the sliding rail, the sliding plate, the sliding assembly and the balls, the moving smoothness of the sliding plate on the sliding rail by means of the sliding assembly is improved, the snapping time of an asphalt test piece is more accurate, and the working efficiency is improved. And the accuracy of actual experimental data is ensured.

A method for acquiring a forming limit of a metal sheet according to the present invention comprises: forming a test piece 100 of a metal sheet using a plurality of molding dies 11 having different shapes so as to generate various forces in the sheet thickness direction; and determining, as indices of the forming limit of the metal sheet, the forces in the sheet thickness direction generated in the formed test piece 100, and the maximum principal strain and the minimum principal strain of the test piece 100 formed so as to generate the forces in the sheet thickness direction.

The application relates to the technical field of batteries, and discloses a system and a method for monitoring elongation, which comprises a roller for rolling an electrode sheet, the electrode sheet moving along a tape running direction, an encoder for triggering a pulse when the electrode sheet moves, a first detection module for collecting a pre-rolling image of the electrode sheet in response to the pulse, a second detection module for collecting a post-rolling image of the electrode sheet in response to the pulse, and a control module for aligning the pre-rolling image and the post-rolling image, and calculating a first elongation of the electrode sheet in a direction perpendicular to the tape running direction according to the aligned images. The application ensures that the two detection modules are synchronously detected through the pulse triggered by the encoder when the electrode sheet moves, and ensures that the pre-rolling and post-rolling states of the same region of the electrode sheet are shot through image frame alignment, so that the first elongation of the electrode sheet can be calculated without marking the electrode sheet, the first elongation monitoring cost is reduced, and the electrode sheet is not damaged.

The utility model discloses a carbon fiber drapability testing device which comprises a fixed workbench, a guide wheel is rotatably assembled on one side of the fixed workbench, a fixed module is slidably assembled on one side, deviating from the guide wheel, of the fixed workbench, and the fixed module is arranged above the fixed workbench. A bearing workbench is arranged on the side, away from the guide wheel, of the fixed workbench, a cutting-off blade is slidably assembled on the side, close to the fixed workbench, of the bearing workbench, the cutting-off blade is arranged above the bearing workbench, and an imaging plate is fixedly assembled between the fixed workbench and the bearing workbench. A fluorescent lamp is fixedly assembled on the side, away from the imaging plate, of the fixed workbench. According to the carbon fiber drapability testing device disclosed by the utility model, a mode of measuring light imaging is adopted, so that the shaking of a fiber end point caused by direct measurement is reduced, the measurement error of the horizontal distance between the fiber end point and a vertical line is reduced, and the accuracy of carrying out drapability testing on the carbon fiber is improved.

The utility model relates to a hydraulic underwater mechanical structure pipe clamp, including main part (1), annular top tight device (2), hydraulic open and close support (3), hoist device (4), bolt sleeve (5), bottom fixed device (6), annular sealing rubber (8), axial sealing rubber (9), axial fastening bolt (10), sacrifice anode (11), pressure test hole (12), T type bolt (13), dust ring (14), pressure sensor (16), pressure test washer (17), annular fastening bolt (21), hydraulic cylinder (22), the main part includes two semicircular housings of symmetrical settings, the top hinged connection of two semicircular housings, annular top tight device sets up in the left and right two end parts of two semicircular housings, pressure sensor sets up on pressure test hole of one semicircular housing.

The invention discloses a cable thermal extension automatic test device, and belongs to the technical field of thermal extension tests. Comprising a case, a driving push rod, a test rack, a calibration group rack, an upper chuck assembly, a clamp assembly, a release mechanism and an image acquisition unit, an inner container box body and a slidable sample drawer are arranged in the case; the driving push rod drives the drawer to enter and exit; the releasing mechanism is arranged above the box body and used for driving the upper chuck assembly to release the clamp assembly. According to the invention, the release mechanism presses down the upper chuck assembly to trigger the internal mechanism to push out a sample, a guide chute is utilized to guide the clamp assembly to slide down and turn over, and the buffer locking assembly is matched to absorb impact and implement mechanical locking, so that automatic load release is realized, non-contact measurement is carried out in combination with the image acquisition unit, full-process automation of the test is realized, and the test efficiency is improved. Manual reading errors are avoided, and the detection accuracy and efficiency are improved.

The invention relates to the technical field of fine copper wire stretching devices, and discloses a fine copper wire stretching device and method for tensile strength and elongation analysis, the fine copper wire stretching device comprises a base, and further comprises a testing part mounted on the base; the tension adjusting part is arranged on the base; the number of the stretching parts is two, and the two stretching parts are both installed on the base; the testing part comprises a fixing assembly, and the fixing assembly is installed on the base; the testing assembly is arranged on the base, and the testing assembly comprises a grating ruler and a tension sensor. By arranging the testing part, the problems that in the using process of an existing copper wire stretching device, tensile strength and elongation analysis on a copper wire is inconvenient, so that the finished copper wire needs to be tested independently, additional procedures and testing cost are increased, the production period is prolonged, and the production efficiency is reduced are solved.

A mechanical extension experiment demonstration device belongs to the technical field of mechanical experiment equipment, and comprises an experiment table and a rope, the experiment table is provided with a demonstration mechanism and is used for carrying out an extension experiment on the rope, and the demonstration mechanism comprises an execution assembly which is arranged on the experiment table and is used for applying a pulling force to the rope; the fixing assembly is arranged on the experiment table and used for fixing the two ends of the rope; the anti-disengaging assembly comprises a barrel shell arranged on the fixing assembly, a packing head placed in the barrel shell, a plurality of open grooves formed in the packing head and distributed in the circumference, a packing sleeve placed in the barrel shell, the packing sleeve is arranged on the packing head in a sleeving mode, and a plug sleeve is installed at the lower end of the barrel shell in a threaded mode; the fixing assembly comprises vertical frames fixed to the two sides of the top of the experiment table and four-jaw chucks installed on the inner walls of the upper ends of the vertical frames. When the rope accidentally falls off in the stretching process, the end of the rope can be limited to be separated from the fixing assembly through the anti-falling assembly, and therefore accidents are avoided.