81 results about "Torsion fatigue" patented technology

The invention belongs to the field of prediction of fatigue failure caused by surface defects under rolling contact loads, and particularly relates to a rolling contact fatigue pitting corrosion prediction method considering crystal plasticity, a corresponding computer readable storage medium and electronic equipment. The method comprises the following steps: S1, constructing a crystal plastic constitutive model of a coupling damage accumulation theory; s2, developing the model in the step 1 into a UMAT subprogram by using Fortran, and embedding ABAQUS into the UMAT subprogram; s3, establishing a representative volume element crystal plastic finite element model; s4, applying a periodic boundary condition and a shear load, obtaining a shear stress-strain curve, carrying out a torsional fatigue test, obtaining fatigue damage parameters of the material, and determining constitutive model parameters of the material; s5, establishing a crystal plastic finite element model of the roller and raceway contact pair; s6, applying boundary conditions in two steps; and S7, observing a damage evolution path to the surface, and obtaining the rolling contact fatigue pitting corrosion life. The method can fill the blank of rolling contact fatigue pitting corrosion prediction methods at present.

The automobile part torsional fatigue test bench comprises a bench body, a driving mechanism is arranged at one end of the top surface of the bench body, a workpiece carrying structure is arranged at the other end of the top surface of the bench body, a force application structure is arranged at the position, close to the driving mechanism, of the top surface of the bench body, and the driving mechanism comprises a driving bin. The end, away from the force application structure, of the driving bin is fixedly connected with a servo motor, and the two sides of the middle of the interior of the driving bin are fixedly provided with a cycloidal-pin wheel speed reduction assembly and a planetary speed reduction assembly correspondingly. The driving mechanism is driven by the servo motor, a huge oil supply hydraulic system does not need to be used, the occupied area is small, the output torsion load can be switched through the cycloidal-pin wheel speed reduction assembly or the planetary speed reduction assembly, the load output through the planetary speed reduction assembly is low, constant loads can be repeatedly applied to a workpiece for a long time, and the working efficiency is improved. The output load of the cycloidal-pin wheel speed reduction assembly is high, destructive testing of the maximum load can be carried out, and two detection modes can be considered.

The invention belongs to the field of fatigue testing devices, and provides a microcomputer-controlled high-low temperature vertical torsional fatigue testing machine which comprises a machine base, vertical frames installed on the upper surface of the machine base, upper cross beams installed on the top walls of the two vertical frames, lifting cross beams slidably installed on the inner walls of the vertical frames, a first motor installed in an inner cavity of the machine base, and a speed reducer installed at the output end of the first motor. The clamping assembly comprises a torsion clamp and an upper clamp; the first lifting assembly controls the lifting cross beam to ascend and descend; a high-low temperature box; a high-temperature furnace; by arranging the clamping assembly, the first lifting assembly, the second lifting assembly, the high-low temperature box and the high-temperature furnace, the temperature of the torsion test covers a wide temperature range from extreme high temperature to deep cooling, and the thermal-mechanical coupling fatigue characteristics of a material in multiple scenes such as high-temperature creep and cold and hot impact can be accurately simulated.

The utility model relates to the technical field of cable processing, and belongs to a cable fatigue detection device. Comprising a workbench, the workbench is provided with a first mounting base and a second mounting base, the first mounting base is provided with a first clamping assembly, the second mounting base is provided with a torsion mechanism, the torsion mechanism comprises a torsion disc, and the torsion disc is provided with a reciprocating bending mechanism; the reciprocating bending mechanism comprises a reciprocating driving assembly and a second clamping assembly. The torsion of the to-be-tested cable can be realized through the torsion mechanism, the torsion fatigue strength of the cable can be detected, the reciprocating bending of the to-be-tested cable can be realized through the reciprocating driving assembly, the bending fatigue of the cable can be detected, multiple detections can be realized through a single device, and the detection efficiency is improved. The functionality of the device is improved, and the detection efficiency is improved.

The present invention relates to the technical field of aerostat load-bearing structure equipment, and discloses a carbon fiber composite material load-bearing rod and a manufacturing method thereof, wherein the carbon fiber composite material load-bearing rod comprises a base shaft and two embedded pipe joints, the outer side wall of the base shaft is provided with a first fiber bundle winding layer; the base shaft comprises a middle section and connecting sections at both ends, the embedded pipe joint is sleeved on the outside of the first fiber bundle winding layer corresponding to the connecting section, and a second fiber bundle winding layer is further provided outside the first fiber bundle winding layer corresponding to the middle section; the outer surface of the second fiber bundle winding layer and the outer surface of the embedded pipe joint are jointly covered with a third fiber bundle winding layer. The carbon fiber composite material load-bearing rod effectively converts in-plane failure stress into normal extrusion failure stress by providing a fiber winding layer and an embedded pipe joint, greatly improving the bearing strength of the load-bearing rod, and has excellent tensile, compression, torsion, fatigue and impact resistance.

The invention relates to the technical field of blade testing, and discloses a blade torsional fatigue testing system and method.The blade torsional fatigue testing system comprises a test bed foundation and at least one torsional vibration exciter, and the test bed foundation is suitable for fixing the root of a blade; the torsional vibration exciter comprises a vibration excitation unit and a blade clamp, the blade clamp is suitable for being clamped and fixed to a blade, the vibration excitation unit is fixed to the blade clamp, and the vibration excitation unit is configured to apply torsional loading to the blade. The blade root is rigidly fixed through the test bed foundation, and displacement interference in the non-torsion direction is prevented from being generated in the test process; a blade clamp of the torsion vibration exciter is clamped on a specified section of a blade, a vibration excitation unit is directly fixed on the surface of the blade clamp through a mechanical connecting piece, the vibration excitation unit generates periodically changing rotating torque during operation, the torque is transmitted to the blade through the blade clamp, and the blade is forced to generate reciprocating torsion deformation around the axis of the blade. And the torsional fatigue load under the actual working condition is simulated.

The invention relates to the technical field of torsion tests, and discloses a high-speed transmission shaft torsion fatigue strength detection device which comprises a workbench, a torsion machine base and a detection machine base arranged on the top of the workbench, and an overload disconnection protection mechanism. The output end of the torsion machine base is in butt joint with a transmission shaft a through an overload disconnection protection mechanism, and the overload disconnection protection mechanism is used for judging the state of the transmission shaft a and disconnecting torsion output when the transmission shaft a is in a torsion bending state to prevent the transmission shaft a from being broken. The overload disconnection protection mechanism is arranged on the basis of traditional detection equipment, state detection is carried out on the transmission shaft a in torsional fatigue strength detection, whether the transmission shaft a of the detection part has a breaking risk or not is predicted, and meanwhile torsion output of the equipment can be rapidly interrupted when it is judged that the transmission shaft a is in an abnormal state; and the torsion applied to the transmission shaft a is released, so that the transmission shaft a in an abnormal state is prevented from being broken due to continuous stress.

The invention discloses an intravascular stent bending torsion fatigue test device, and belongs to the technical field of fatigue test machinery. The intravascular stent bending torsional fatigue test device comprises a rack, the rack comprises a door-shaped support, a back plate and a base, the door-shaped support is provided with a bending load module, the bending load module comprises a first stepping motor, the output end of the first stepping motor penetrates through the back plate and is fixedly connected with an eccentric wheel through an extension shaft, and a pair of sliding blocks is additionally arranged; a sliding rail is arranged on the inner side of the door-shaped support, the sliding blocks are arranged on the sliding rail, a cantilever is connected between the pair of sliding blocks, the top of the cantilever is connected with the lower side of the top of the door-shaped support through a spring, a plurality of first loading connectors are arranged on the front face of the cantilever, and a torsion module is additionally arranged. The fatigue durability under bending-torsion dual loads can be tested, and the fatigue performance of the stent under the condition of blood vessel deformation during limb movement can be truly simulated.

The invention discloses a device, a method and equipment for evaluating the torsion resistance of a wind power generation cable, and belongs to the technical field of electric power facilities. The device comprises a cable sample acquisition module used for acquiring a cable sample of a wind power generation cable; the simulation control module is used for adopting a mechanical device with a multi-axis torsion function to respectively carry out torsion simulation control for simulating fan yaw torsion, tower torsion and cable laying shape torsion on the cable sample; and the detection module is used for carrying out torsional fatigue detection and electrical performance detection on the cable sample, and determining torsional performance evaluation information of the cable sample of the wind power generation cable according to a detection result. According to the technical scheme, the torsion resistance of the wind power generation cable can be accurately evaluated, the stable operation of the wind power generation cable is ensured, the energy conversion efficiency is prevented from being influenced by the reduction of the torsion resistance of the wind power generation cable, the time and material resource loss caused by subsequent maintenance and fault inspection is avoided, and the operation stability of a wind generating set is improved.

The invention relates to the technical field of cable manufacturing, and discloses a preparation method of a high-torsion-resistance special cable, which comprises the following steps of: when a cable insulating layer is in a critical plastic state, synchronously applying a circumferential shear force field and cooling through a dynamic unit so as to construct and lock a macromolecular chain microstructure oriented along the circumferential direction on line, and simultaneously forming a high-torsion-resistance special cable. A dynamic unit is used as a sensor to monitor the dielectric property in the phase change process of the insulating layer in real time, and process parameters are adjusted in a closed-loop feedback mode on the basis of the monitoring result, the micromorphology of the insulating layer is actively reconstructed on line, and a molecular chain disordered freezing structure caused by traditional rapid cooling is changed into an unordered freezing structure. According to the invention, the tensile strength of the cable is changed into an ordered toughness system which is arranged along the circumferential direction and can dissipate stress energy through internal slippage, so that the torsional fatigue resistance mechanism of the cable is qualitatively changed, and the closed-loop regulation and control of the microstructure forming process ensure the production consistency of the high performance of the product under different batches of raw materials.

This utility model relates to the technical field of torsional fatigue testing devices, specifically a shaft-type torsional fatigue testing device, including a first support and a second support. The first and second supports are rotatably connected to a first rotating shaft and a second rotating shaft arranged coaxially. A flange is fixedly connected to one end of the first and second rotating shafts that are close to each other. A rocker arm is fixedly connected to the first rotating shaft. The middle of a balance arm is fixedly connected to the second rotating shaft. Measuring arms are hinged to both ends of the balance arm, and a fixed seat is hinged to the end of the measuring arm away from the balance arm. A load sensor is fixedly connected to the middle of the measuring arm. This utility model uses a balance arm, a rocker arm, and a load sensor to measure torque instead of a torque sensor. When the torque is large, the length of the balance arm is increased to increase the length of the lever arm, reducing the force measured by the load sensor, so that the force value is within the range of the load sensor, thus completing the torsional test.

The invention belongs to the field of shaft testing, and particularly relates to automobile transmission shaft assembly torsional fatigue testing equipment which comprises a testing seat, a driving table used for controlling a to-be-tested shaft to rotate is arranged in the middle of the testing seat, and a moving table connected with the to-be-tested shaft is arranged on the top face of the testing seat. The movable table can change the resistance between the movable table and the test seat, a center seat is arranged in the middle of the test seat, an adjusting column is fixedly connected to the top of the center seat, and multiple monitoring modules used for monitoring fatigue data of a to-be-tested shaft are arranged in the test seat. The real bending moment and radial force brought by revolution are closer to the real stress state of wheel rolling, so that the authenticity of detection data is improved; meanwhile, due to scene simulation during detection, multiple detection data indexes are added, more detection data can be obtained, and a more accurate measurement result can be obtained through the data.

The application discloses a passenger car four-channel chassis component durability test device and relates to the field of durability tests, which comprises a test frame main body, a tractor one installed at the bottom of the test frame main body, a tractor two installed at the left side of the test frame main body, a tractor three installed at the right side of the test frame main body and a control module installed on the front of the test frame main body, wherein the tractor one, the tractor two and the tractor three are used for fixing the tested components and conducting horizontal, vertical and torsional fatigue tests; a prediction model is constructed, the test state of a future period is predicted and obtained based on the test data of the current test project, the mapping relationship between the initial period damage state of the test component and the future period fission and deformation state is analyzed, and then the long-term test performance of the tested object can be quickly obtained through short-term actual tests.

The present invention relates to an electric resistance welded steel pipe having excellent workability and torsional fatigue resistance and a method for manufacturing the same. The electric resistance welded steel pipe 1 comprises a weld region 3, which is an area within ±10 degrees in the pipe circumferential direction from an electric resistance weld seam 2 formed along the pipe length, and a base material region 6 outside the weld region 3. The pipe has an r value of 1.0 or greater in the pipe length direction, and a minimum wall thickness Ts of the weld region 3. (MIN) (mm) and the average wall thickness Tb of the base material area 6 (Ave) (mm) difference (T b(Ave) ‑Ts (MIN) ) and the arc length W (mm) of the inner surface of the pipe in the weld area 3 satisfy the following formula (1), the maximum wall thickness Ts of the weld area 3 (MAX) (mm) and Tb (Ave) (mm) satisfies the following formula (2). H / W≤0.10…Formula (1) Ts (MAX) / Tb (Ave) ≤1.05…Formula (2).

The utility model discloses a coal mine sampling device, which relates to the technical field of sampling devices, and comprises a sampling barrel, a sampling pipe, a sampling pipe and a sampling pipe, the spiral shaft is rotationally mounted in the sampling barrel, and a gap is reserved between the spiral shaft and the inner wall of the sampling barrel; the discharge hole is formed in one end, far away from the sampling hole, of the sampling barrel; the power source is mounted at one end of the sampling barrel and is in transmission connection with the spiral shaft; the at least one reinforcing rib is fixed to the edge position of the spiral shaft in the axial direction, and the reinforcing rib extends into the gap in the rotating direction of the spiral shaft; by means of the reinforcing ribs fixed to the edge of the spiral shaft in the axial direction, the overall rigidity and torsional strength of the spiral shaft are improved, the spiral shaft is effectively prevented from deforming or being subjected to torsional fatigue due to the action of torque and bending moment in the long-distance conveying process, and therefore the service life of the spiral shaft is remarkably prolonged.

The invention belongs to the technical field of brake fatigue performance test, and particularly relates to a double-channel torsional fatigue test device. The device comprises a double-channel driving mechanism and transmission systems which are symmetrically arranged, the double-channel driving mechanism comprises a base, a bidirectional driver, a motor and a driving shaft, each transmission system comprises a frame, a power shaft, an electric control clutch, a protection cylinder and a rotating cylinder, and the power shafts and the rotating cylinders are coaxially arranged; and the front end of the rotary drum is provided with an extension drum and is respectively provided with a brake disc mounting seat and a brake mounting seat. Swing arms are arranged on the two sides of the rotary drum, the swing arm on one side is connected with tension and compression sensors arranged up and down through a push-pull rod and used for detecting bidirectional torque generated in the braking process, and the swing arm on the other side limits the swing angle of the rotary drum through a limiting pull rod. Selective connection or separation of the transmission systems on the left side and the right side is achieved through the electric control clutch, and the other side can still be tested independently when one side breaks down.

The utility model discloses a torsional fatigue test system after corrosion of a steel sheet pile, which comprises a corrosion device and a torsion device, the corrosion device comprises a corrosion assembly and a liquid storage tank, the steel sheet pile is inserted in the corrosion assembly, the corrosion assembly and the liquid storage tank are connected through a circulation assembly, and a blowing assembly is arranged on the corrosion assembly; the torsion device comprises a support, clamping assemblies are rotationally arranged at the upper end and the lower end of the support, gear rings are fixedly arranged on the clamping assemblies, teeth are arranged on the outer circle faces of the gear rings, a motor is fixedly arranged on the support, the motor is in transmission connection with a gear, and the gear is meshed with the gear rings. According to the utility model, the steel sheet pile is inserted into the corrosion device for corrosion environment simulation, so that the steel sheet pile is corroded in a simulated use state, and then the steel sheet pile is put into the torsion device for torsion fatigue test until the steel sheet pile is broken, thereby obtaining torsion fatigue data of the steel sheet pile after corrosion. The method is used for judging reuse times of the steel sheet pile.

The invention discloses a dynamic torsional fatigue test device and method for an automobile transmission shaft intermediate support assembly, and relates to the technical field of transmission shaft test devices.The dynamic torsional fatigue test device comprises an experiment table, an output motor is fixedly connected to the top of the experiment table, an output shaft of the output motor is connected with a transmission shaft through a universal joint, and the dynamic torsional fatigue test device further comprises a connecting shaft connected with the transmission shaft; one end of the connecting shaft is rotationally sleeved with a connecting sleeve, and an adjusting assembly used for angle adjustment is arranged on the outer side of the connecting sleeve. The angle between the connecting shaft and the transmission shaft is adjusted through the adjusting assembly, the variable-angle working state of the transmission shaft caused by suspension jumping or installation errors in the vehicle running process can be simulated, the torsional fatigue test is closer to the actual driving working condition, and therefore the authenticity and reliability of test data are improved.

The present invention provides a tension-compression test fixture and a fatigue test method for bolt-connected thin-walled plate members. The tension-compression test fixture includes upper and lower clamping arms installed on a tension-torsion fatigue testing machine. The two clamping arms have the same structure and are arranged oppositely in an upper and lower staggered manner. Each clamping arm respectively includes a cross beam, a fastening slider, and a clamping rod. The upper three-jaw chuck of the tension-torsion fatigue testing machine clamps the clamping rod provided on the upper clamping arm; the lower three-jaw chuck of the tension-torsion fatigue testing machine clamps the clamping rod provided on the lower clamping arm. The test fixture provided by the present invention can effectively clamp bolt-connected thin-walled plate members of different specifications, making it difficult for the bolt-connected thin-walled plate members to slip, and ensuring that the bolt-connected thin-walled plate members undergo fatigue fracture in the connection weak area. The fatigue test method provided by the present invention can accurately obtain the load-life curve, and then predict the fatigue life of the specimen to ensure the service safety of the bolt-connected thin-walled plate members, and its simulation effect of the test is good.

This invention discloses a multidimensional mechanical fatigue testing system based on high-temperature environments, specifically relating to the field of testing machine technology. The system includes: a torsional fatigue testing module, a tensile-compressive fatigue testing module, a high-temperature environment control module, a servo-hydraulic control module, and a temperature influence correction unit. This multidimensional mechanical fatigue testing system based on high-temperature environments integrates torsional fatigue testing and tensile-compressive fatigue testing modules, enabling the simultaneous application of multidimensional alternating loads such as torsion and tension / compression. Simultaneously, the high-temperature environment control module dynamically adjusts the temperature, and combined with the temperature influence correction unit and a series of accuracy correction formulas, effectively eliminates the interference of high temperatures on material properties and sensor accuracy. It avoids data distortion caused by the lack of a systematic temperature correction mechanism, making the test results closer to actual service conditions and providing more reliable performance data for engineering applications.

The invention provides a coupler torsional fatigue test device, which comprises a base, a movable seat and a fixed seat, and is characterized in that the movable seat comprises a fixed column and a shaft sleeve and is rotationally connected with the fixed column; the fixed bearing seat is coaxially and rotatably connected with the shaft sleeve; the synchronous clamping mechanism comprises a clamping block which is in sliding connection with the shaft sleeve; the first spring is located on the side, away from the fixed bearing seat, of the clamping block. The driving block is fixedly connected with the clamping block and is positioned at one end part of the fixed bearing seat; the coaxial driving mechanism is located on the base, comprises a driving motor, is coaxially arranged with the fixed bearing seat and is in sliding connection with the base; and the synchronous driving unit is coaxially connected to the end part of the driving motor and is used for extruding the driving block to drive the clamping block to be separated from the clamping groove and clamping the fixed bearing seat to synchronously drive the fixed bearing seat to rotate. According to the technical scheme, the power switching of the fixed bearing seat is realized, so that the torsional fatigue test of the coupler has different functions.

The invention provides a bending-torsional fatigue testing device, relates to the technical field of bending-torsional fatigue testing, and is used for solving the technical problem that a rotary bending fatigue testing device is complex in structure. The bending-torsional fatigue testing device comprises a base, two loading assemblies and a tested piece, and the base is provided with two arc-shaped rails; the two arc-shaped rails are symmetrically arranged on the base in the first direction. The two loading assemblies are movably connected with the two arc-shaped rails respectively, and one loading assembly is connected with one arc-shaped rail; each loading assembly comprises two loading pieces, and the two loading pieces move along the corresponding arc-shaped rails in the direction close to each other or away from each other; the tested piece is located between the two loading assemblies, and each loading piece is in direct contact with the tested piece. The testing device is used for detecting and evaluating the bending-torsional fatigue life of the tested piece, and the testing device is simple in structure.

The invention discloses a device, a method and equipment for evaluating the torsion resistance of a wind power generation cable, and belongs to the technical field of electric power facilities. The device comprises a sample acquisition module used for acquiring a cable sample of a wind power generation cable; the torsion simulation module is used for twisting the cable sample through a multi-axis torsion mechanical device so as to simulate multi-direction torsion stress applied to the wind power generation cable; and the detection and evaluation module is used for carrying out torsional fatigue detection and electrical performance detection on the cable sample so as to identify whether the cable sample has insulation damage abnormity and / or electrical performance abnormity, and a torsional performance evaluation result of the wind power generation cable is obtained. According to the technical scheme, the cable sample is twisted through the multi-axis torsion mechanical device to simulate the multi-direction torsion stress applied to the wind power generation cable, the cable sample is detected, the actual working condition of the wind power generation cable can be comprehensively considered, and comprehensive, accurate and innovative torsion resistance evaluation of the wind power generation cable is achieved.

A method for predicting a multiaxial fatigue life. The method includes: obtaining a first temperature rise value of a to-be-tested material in a first cycle; determining first inherent dissipation energy of the to-be-tested material in the first cycle according to the first temperature rise value and a time constant; and determining the multiaxial fatigue life of the to-be-tested material according to a first proportional value, the first inherent dissipated energy, axial fatigue test parameters and torsional fatigue test parameters; the first proportional value is a ratio of an axial strain amplitude to a torsional strain amplitude of a multiaxial fatigue test, the axial fatigue test parameters are configured to represent an axial fatigue resistance of the to-be-tested material, and the torsional fatigue test parameters are configured to represent a torsional fatigue resistance of the to-be-tested material.

1. The name of the design product: torsional fatigue test platform. 2. The use of the design product: to perform torsional fatigue test of materials. 3. The design points of the design product: in shape. 4. The picture or photo that best shows the design points: perspective view.

The embodiment of the invention discloses a wind power generation cable torsion resistance evaluation method and system based on a mechanical electromagnetic coupling model, and the method comprises the steps: obtaining the mechanical electromagnetic coupling feature information of a wind power generation cable in an actual use process, performing model construction based on the mechanical electromagnetic coupling feature information to obtain a mechanical electromagnetic coupling model, performing simulation action on the to-be-evaluated wind power generation cable based on the mechanical electromagnetic coupling model and the preset action period parameter data, and after a preset number of action periods, performing evaluation on the to-be-evaluated wind power generation cable. And obtaining torsion resistance test data and torsion fatigue resistance data of the to-be-evaluated wind power generation cable output by the mechanical electromagnetic coupling model, and determining a torsion resistance evaluation result of the to-be-evaluated wind power generation cable according to the torsion resistance test data and the torsion fatigue resistance data. According to the scheme, the torsion resistance data of the cable is predicted and evaluated through the mechanical electromagnetic coupling model, and comprehensive, accurate and intelligent evaluation of the torsion resistance of the wind power generation cable can be realized.

To provide a torsional fatigue evaluation method that can evaluate the torsional fatigue of a metal using an electromagnetic acoustic wave.SOLUTION: A torsional fatigue evaluation method according to the present invention is a method for evaluating the torsional fatigue of a metal to be evaluated, and comprises: measurement steps S1 and S3 for measuring a sound velocity (or a resonance frequency) of an ultrasonic wave of an axisymmetric SH wave propagating in the evaluation target; and evaluation steps S4, S5 for evaluating the torsional fatigue of the evaluation target based on the sound velocity (or the resonance frequency) measured in the measurement steps S1 and S3.SELECTED DRAWING: Figure 7

The utility model relates to the technical field of torsion tests, and discloses a torsion fatigue test device which comprises a shell, the top end of the shell is connected with a protective cover in a sliding mode, the left end and the right end of the shell are fixedly connected with connecting shells, the left end and the right end of the protective cover are fixedly connected with inserting blocks, and the interiors of the connecting shells are fixedly connected with fixing shells. An inner shell is fixedly connected to the interior of the fixing shell, a limiting ring is slidably connected to the interior of the inner shell, a thrust spring is fixedly connected to the end, away from the connecting shell, of the limiting ring, and a mounting column is fixedly connected to the interior of the limiting ring. According to the utility model, the inserting block is inserted into the connecting shell, so that the thrust spring pushes the mounting column to move towards the connecting shell, the mounting column slides into the connecting shell, a plurality of bolts do not need to be screwed, the maintenance and repair process of equipment is facilitated, the downtime is reduced, the working efficiency is improved, and meanwhile, when the protective shell is damaged, the protective shell can be replaced in time.

The invention discloses a torsion rod spring torsional fatigue life prediction method considering residual stress gradient evolution, and the method comprises the steps: carrying out the pre-torsion processing of a torsion rod spring test piece at different pre-torsion angles, and obtaining a torque-torsion angle curve at different pre-torsion angles; obtaining a relation curve of the torsion residual shear stress and the torsion angle; obtaining a relation curve of the torsion residual shear stress and the radius of the test piece based on a plane hypothesis theory; obtaining the magnitude and distribution curve of the residual stress after evolution of different fatigue cycles through analog simulation; fitting the evolved residual stress gradient curve to obtain a comprehensive parameter reflecting the residual stress gradient distribution; and establishing a fatigue life prediction model to predict the fatigue life of the test piece under different pre-torsion angles. According to the method, the residual stress evolution law of the pre-twisted torsion rod spring test piece is taken as a research object, the fatigue life of the torsion rod spring test piece under different pre-torsion angles can be predicted and evaluated, and the method has relatively good prediction precision.

The application discloses a metal material torsional fatigue life prediction method based on M-integral, and comprises the following steps: selecting a far-field closed integral path C surrounding a defect in a material, calculating three-dimensional M-integral and equivalent damage volume V of the defect D , judging damage degree of the material according to the size of V D ; defining a fatigue damage evolution rate as dV D / dN, defining a fatigue driving force as AM / A P , and establishing a metal material torsional fatigue model based on M-integral; a torsional fatigue experiment evaluation is conducted on a DD6 nickel-based alloy, and effectiveness of the fatigue model is verified. The torsional fatigue model provided in the application can uniformly describe damage processes under torsional fatigue load, including formation of a plastic zone, initiation of a micro crack and expansion of a macro crack, a standard for evaluating damage degree and predicting fatigue life of a metal material or structure under torsional fatigue load is provided, and the application has important significance for metal material damage and life prediction analysis.