50 results about "Tensile fatigue" patented technology

The invention provides a self-adaptive double-entropy-multi-scale Transform unsupervised cross-domain composite material damage prediction method, which comprises the following steps: preprocessing an acoustic emission signal and extracting a double-entropy feature matrix based on the acoustic emission signal acquired by a composite material test piece under a tensile-tensile fatigue load; constructing a data set based on the double-entropy feature matrix and training a damage evolution model; and inputting the double-entropy feature matrix corresponding to an acoustic emission signal into the trained damage evolution model based on the acoustic emission signal acquired by the composite material test piece under the shear fatigue load, so as to realize real-time prediction of the shear fatigue damage. According to the method, the cross-load high-reliability prediction is realized, the feature dimension redundancy is improved, the physical interpretability is improved, the supervision marking cost is reduced, and a brand new solution is provided for engineering application.

The invention discloses an air pressure-temperature-damage coupled flexible material air tightness test system and method.The test system comprises a tensile fatigue device, sample holders, a high-pressure permeation device, a fixing and supporting device and a lifting device, and the two ends of a sample are fixed through the sample holders; the method comprises the following steps: firstly, fixing a sample holder on a tensile fatigue device to carry out a cyclic tension test so as to obtain samples with different fatigue damage degrees; the circularly tensioned sample is transferred and fixed on the fixed supporting device through the lifting device, so that a central test area of the sample is positioned in a high-pressure sealing box permeation area formed by an upper box assembly and a lower box assembly in the high-pressure permeation device, and air tightness detection is performed at different temperatures and different air pressures; therefore, the gas permeability and the gas permeability coefficient of the sample are obtained, and comprehensive evaluation of the gas tightness and the fatigue resistance of the flexible material is realized.

The invention relates to the technical field of pavement material mechanical property testing, and discloses a pavement material deformation adaptability fatigue testing machine, which comprises a servo drive and control system, a mechanical transmission system and a structure support and reference system, the servo drive and control system comprises a servo motor, a PLC, a servo driver and an analog quantity output module, the PLC is electrically connected with the analog quantity output module, the analog quantity output module is electrically connected with the servo driver, and the servo driver is electrically connected with the servo motor. The load coverage range is wide, the test requirements of pavement material test pieces with different strengths are met, the requirements of various mechanical property tests on loads are met, the loading modes are flexible and diversified, single loading such as horizontal stretching, stretching containing vertical deformation and fatigue stretching circulation can be achieved, and the test efficiency is improved. The device can be combined with MMLS3 small acceleration loading equipment to realize composite loading of tire cyclic load and test piece deformation, and composite working conditions of the seamless expansion joint in actual service are accurately simulated.

The invention relates to the technical field of rubber hose detection, and particularly discloses an anti-drawing fatigue detection device and method based on rubber hose production, and the device comprises installation mechanisms which are arranged at the inner side of a frame body and are symmetrically distributed with respect to the central point of the frame body, and are used for fixing a rubber hose from the end part. According to the invention, the symmetrically arranged mounting mechanisms are arranged in the frame body, so that the two ends of the rubber hose are synchronously stretched, the internal stress distribution of the rubber hose is more uniform, and the overall tensile property of a material can be reflected more truly; and the fluid circularly flows in the rubber hose through the flow guide mechanism, so that the actual conditions such as high-temperature fluid or low-temperature fluid conveyed in the rubber hose are simulated, the anti-drawing fatigue performance of the rubber hose is detected, and the detection accuracy and authenticity are improved according to the actual application scene.

The application discloses a kind of air pressure-temperature-damage coupling's flexible material air tightness test system and method, test system includes tensile fatigue device, sample holder, high-pressure permeation device, fixed support device and holder, the two ends of sample are fixed by sample holder, first fixed in tensile fatigue device to carry out cyclic tension test with sample holder, to obtain the sample with different fatigue damage degree;Through holder, the sample after cyclic tension is transferred and fixed on fixed support device, so that the center test area of sample is located in the high-pressure sealed box permeation region formed by upper box assembly and lower box assembly in high-pressure permeation device, so as to carry out air tightness detection under different temperature and different air pressure, to obtain the gas permeation rate and gas permeation coefficient of sample, realize the overall evaluation of flexible material air tightness and fatigue resistance.

The invention discloses a method for improving the tensile fatigue performance of a thin-wall Ti6Al4V titanium alloy, and belongs to the technical field of metal material processing, and the method comprises the following steps: S1, determining femtosecond laser shock peening parameters based on material performance parameters; s2, setting a laser processing path through a laser processing system control end; according to the method, the ultrahigh pressure shock waves generated by the femtosecond laser shock peening technology initiate strong plastic deformation on the surface layer of the material, the plastic deformation forms a dislocation structure with higher density by inducing dislocation motion and proliferation, the strength and hardness of the material are further improved, in addition, the plastic deformation can cause the surface layer of the material to generate compressive residual stress, and the mechanical property of the material is improved. According to the invention, due to the existence of the residual stress, the external tensile stress is effectively resisted, the damage accumulation of the material in high-cycle fatigue is delayed, and the proliferation and slippage of dislocation are delayed, so that the fatigue resistance of the material is further improved.

The utility model belongs to the technical field of tensile fatigue testing, and particularly relates to tensile fatigue testing equipment which comprises a frame body, a testing table, a first tensile seat, a second tensile seat and a driving assembly, the testing table is connected with the frame body, the first tensile seat and the second tensile seat are both connected with the testing table, and the driving assembly is connected with the first tensile seat and the second tensile seat. The first stretching seat is provided with a first locking structure, the first locking structure is used for locking one end of a headband on the first stretching seat, the second stretching seat is provided with a second locking structure, the second locking structure is used for locking the other end of the headband on the second stretching seat, and the driving assembly is connected with the test board. The driving assembly can drive the first stretching base to move in the direction close to or away from the second stretching base. The driving assembly can accurately adjust the distance between the first stretching seat and the second stretching seat according to design requirements, the stretching distance of each time can be accurately controlled, and the accuracy of the measured stretching frequency limit is improved.

The utility model relates to a wire tensile fatigue strength detection device, which comprises a mounting platform, a fastening end, a moving end, a tension output part and an operation and display panel, the fastening end and the moving end are each provided with an annular clamping structure, and the operation and display panel is electrically connected with the fastening end, the moving end and the tension output part. According to the device provided by the utility model, the wire rod is clamped by the clamping structure through operation on the operation and display panel, and then the tension output part pulls the movable end to move along the axis direction of the wire rod, so that a tensile test is carried out on the wire rod, and the tension output part transmits a tension output value of the tension output part to the operation and display panel for display; the clamping structure is simple in structure and convenient for experimenters to observe numerical value changes and record test data, the clamping structure in the embodiment can adapt to wire rods with different diameters, meanwhile, after the wire rods are clamped, the wire rods are not prone to falling off in the test process, the test can be conducted for a long time, more accurate test results can be obtained, and the test efficiency is improved. And the door of the mounting platform can protect the safety of experimenters.

The invention belongs to the technical field of metallurgy, and particularly relates to a 420 MPa-grade wind power steel welded joint with the fatigue grade of DC112 and a preparation method. According to the 420 MPa grade wind power steel welded joint, under the tension-tension fatigue test condition that the stress ratio R is equal to 0.5, after 2 * 106 times of cyclic loading, the fatigue strength of the 420 MPa grade wind power steel welded joint reaches 112 MPa, and the strict requirement for the DC112 grade fatigue grade in the international standard DNV-ST-0126 is completely met. The performance index is obviously superior to the prior art level, and key technical support is provided for high-reliability design and light-weight manufacturing of a wind power tower tube structure.

The invention discloses a high-temperature fatigue test system and a high-temperature fatigue test method for a composite casing mounting seat, and belongs to the technical field of fatigue test of casing mounting seats. The system comprises a biaxial fatigue test device, a test piece, a heating device, a data acquisition assembly and a controller, the test piece is installed on the biaxial fatigue test device, and the heating device and the data acquisition assembly are both connected with the test piece. The controller is electrically connected with the biaxial fatigue test device, the heating device and the data acquisition assembly. The heating device is used for heating the test piece to simulate the high-temperature working condition of the test piece, the biaxial fatigue test device is used for performing biaxial loading on the test piece, and the data acquisition component is used for acquiring strain data of the test piece in the test process, so that the biaxial tensile fatigue test on the composite casing mounting seat is realized. Therefore, the high-temperature fatigue performance of the composite material outer culvert casing mounting seat under the dual effects of the internal pressure and the axial force can be verified.

The invention belongs to the field of fatigue strength testing of metal materials, and particularly relates to a clamping device suitable for tension-tension fatigue performance testing of a linear material and a testing method. A fatigue machine connecting piece is fixed to a fatigue machine, and the load is reset; the long-rod bolt, the springs and the sample upper clamp are assembled, so that the resultant force of the pre-pressure of the two springs is the amplitude of the fatigue load, and the pre-pressure of the springs is reserved; fixing two ends of the linear material by using a winding clamp, and loading to an average value of a fatigue load; mounting the assembled long-rod bolt, spring and sample upper clamp on the sample, and connecting with a fatigue machine connecting sheet; loading to the maximum value of the fatigue load; a sample lower clamp is hung on the sample; the distance between the linear material and the fatigue machine stand column is measured, a tensioner and a U-shaped bolt baffle assembly are installed, and it is ensured that the distance between the linear material and the fatigue machine stand column is not changed; and unloading until the wire rod is bent, clearing the load, and then starting a fatigue test. According to the invention, effective tension-tension fatigue test can be carried out on the linear material, and accurate wire fatigue performance data can be obtained.

To predict a fatigue life of a thermoplastic resin capable of improving prediction accuracy in a range where a stress ratio R is 0 to 1.SOLUTION: A fatigue life prediction method comprising a step of creating a fatigue life prediction diagram of a thermoplastic resin having a stress ratio R of 0 to 1 based on the following formula (1). Where σ a is a stress amplitude, σ m is a mean stress, σ B is a value based on a rupture strength calculated from a result of a tensile test with a stress ratio R of 1, an index x is a value of more than 0 and less than 1.0, and σ w is an intercept obtained by substituting, into the above formula (1), a stress amplitude and a mean stress calculated from a result of a pulsating tensile fatigue test with a stress ratio R of 0 as σ a and σ m, respectively, a value based on the rupture strength as σ B, and a value of more than 0 and less than 1.0 as x. ) SELECTED DRAWING: Figure 2

The utility model relates to a kind of metal composite material high-frequency fatigue test device, including support frame, testing device, protective cover and fixing device, testing device is installed on the support frame, the testing device is used to further test the tensile fatigue strength of metal by constantly increasing the force of stretching;The protective cover is installed on the testing device outside;The fixing device is installed on the testing device, and the fixing device is used to fix the metal to be tested.By the closed transmission chain of motor-reducer-screw integrated in test support, cooperate with the symmetrical limiting rod in displacement groove and displacement block limiting hole, the loading axis and the sample center line always keep high-precision coaxial, avoid eccentric error;Motor support supports reducer independently, suppresses bending deformation and resonance, improves long-term stability;Fixing device realizes sample trace eccentricity compensation, quick plug-in clamping and double-groove limiting positioning with the laminated structure of fixed block-adjusting disc-clamping block-mounting block, and different size samples can be replaced by a person.

The invention discloses a wave-resistant structure for an oil tank in the field of wave resistance of oil tanks. The N supporting assemblies are distributed at intervals in the length direction of the oil tank and fixed in the oil tank; each wave-proof plate is arranged between every two adjacent supporting assemblies and can move up and down in the height direction of the supporting assemblies; the supporting assembly comprises a hollow stand column, a perforated plate is arranged in the stand column and divides the interior of the stand column into an upper cavity and a lower cavity, a plurality of liquid inlets corresponding to the lower cavity are formed in the periphery of the stand column, a floating piece capable of moving up and down along with the oil surface is arranged in the upper cavity, and the floating piece is connected with the wave-proof plate into a whole through a connecting piece. The periphery of the stand column is provided with a limiting groove corresponding to the upper cavity and allowing the connecting piece to penetrate through. Through the three core advantages of replacing material dependence with hydraulic damping, eliminating tensile fatigue through rigid linkage and preventing clamping stagnation through accurate guiding, the reliability problem caused by material aging, repeated stretching and motion instability in a comparison structure is solved.

The invention discloses a stud tensile fatigue test fixture and an assembly method, and relates to the technical field of test fixtures, the stud tensile fatigue test fixture comprises a first fixture and a second fixture which are symmetrically arranged at the two ends of a test bolt, the second fixture and the first fixture each comprise a fixture body, and the bottom of each fixture body is penetrated by the test bolt; a centering assembly is arranged between the test bolt and the clamp body; a fixing assembly is arranged at the end, penetrating through the clamp body, of the testing bolt. By adopting the stud tensile fatigue test fixture and the assembly method, automatic centering of the test bolt and the fixture can be realized, and the accuracy of a test result is improved.

The utility model discloses a clamp structure and a tensile fatigue testing device, and relates to the technical field of material performance tests.The clamp structure comprises a mounting seat, and a groove structure is arranged on the mounting seat; the two clamping pieces are symmetrically arranged in the groove structure; the driving structure comprises a first connecting piece and a second connecting piece, the first connecting piece is rotationally arranged on the mounting base, the second connecting piece is arranged in the groove structure, the second connecting piece can slide from one end of the groove structure to the other end of the groove structure, the second connecting piece is movably connected with the clamping piece, and the first connecting piece and the second connecting piece are connected through a first transmission structure; the first transmission structure is used for converting rotation of the first connecting piece into linear motion of the second connecting piece, and in the process that the two clamping pieces move along with the second connecting piece, the groove structure can make the two clamping pieces close to each other oppositely. The whole clamp structure is humanized in design and convenient to operate, the two clamping pieces can be close to each other in the opposite direction only by rotating the first connecting piece, and the to-be-tested piece is rapidly clamped and fixed.

The application discloses a high-temperature tensile-tensile fatigue test system and method, and designs a clamping device which can adapt to thickness change of a sample and ensure accurate centering of the sample based on a cold clamping mode; a movable thermocouple device is also designed, the thermocouple contacts the sample in the heating and heat preservation stage, and the thermocouple is slid to a position 3-6 mm away from the surface of the sample when the fatigue loading is formally started; and a silica aerogel composite material is selected to make a heat insulation felt which is arranged at the upper opening of a high-temperature furnace to block the hot air flow continuously rising from the high-temperature furnace, eliminate the risk of overheating of the chuck and the sensor system above the testing machine in a long-time fatigue test, and improve the stability and uniformity of the temperature field of the high-temperature furnace. The application makes technical innovations from three aspects of the clamping device, temperature measurement and control and heat insulation of the high-temperature furnace, effectively solves the technical problems of the high-temperature tensile-tensile fatigue test, and improves the technical level of the high-temperature tensile-tensile fatigue test of SiC-based composite materials.

The invention relates to the field of material testing, and discloses a notch cantilever beam-based small sample bending fatigue testing method, which is characterized by comprising the following steps: S1, applying a low-frequency bending symmetric cyclic loading test to the tail end of a beam to obtain a tail end load-displacement curve; s2, establishing a corresponding relation between load-displacement and the true strain amplitude epsilon m and stress amplitude sigma m of the fatigue source RVE through an energy method; s3, a fatigue life estimation model is established according to epsilon m and sigma m, and the fatigue performance of the material is obtained. The Manson-Coffin fatigue life prediction is completed by establishing the relation between epsilon eq (average strain amplitude)-epsilon m (real stress amplitude) and epsilon eq (average strain amplitude)-sigma m (stress amplitude), the traditional experience method that the bending fatigue performance is equivalently replaced by tensile fatigue is overcome, and the test method for detecting the bending fatigue performance of the material is further provided.

The application provides a full-electric instrumented tensile impact fatigue test system, and mainly solves the problems of stress wave pulse transmission in a rod back and forth, non-repeated cyclic loading test and automatic test. The application uses a Hopkinson rod system, a stress wave riveting gun module, a screw drive and a comprehensive detection and controller to realize single repeated impact loading of a test piece, control of the emission and recovery of a projectile body, and closed-loop control of loading force. The application realizes the single loading impact fatigue function of the test piece by energy absorption and a stopper and a screw drive, and realizes instrumented and full-automatic impact tensile fatigue test.

The invention discloses a high-tensile fatigue-resistant adhesive tape material and a preparation method thereof. The core of the high-tensile fatigue-resistant adhesive tape material is to construct a dynamic ionic bond and bio-based coordination bond dual-crosslinking adhesive layer system. The adhesive layer is prepared by taking modified polylactic acid-cellulose nanocrystals as a bio-based matrix, matching with an ionic liquid modifier, introducing modified tea polyphenol and zinc acetate to form a bio-based coordination bond according to a molar ratio of 1: 3-1: 5 through solvent-free melt blending. The bio-based content of the adhesive tape is 50%-70%, the tensile strength is 15-18 MPa, the self-repairing efficiency is 85%-95% at the room temperature for 10-15 min, the 50% strain cycle fatigue resistance frequency is 10000-15000, the problem that the strength and self-repairing of an existing bio-based adhesive cannot be achieved at the same time is solved, and the adhesive tape is suitable for medical and flexible electronic scenes.

The invention discloses a spot welding cross-shaped structural member tensile fatigue test tool, which comprises a first adapter plate and a second adapter plate, five groups of first angle adjusting holes and second angle adjusting holes are respectively arranged on the first adapter plate and the second adapter plate at 0-degree, 30-degree, 45-degree, 60-degree and 90-degree positions, and the adjusting holes at the corresponding positions are combined in pairs for use. The spot welding device is used for spot welding rotation of the cross-shaped structural part at the positions of 0 degree, 30 degrees, 45 degrees, 60 degrees and 90 degrees. The first adapter plate is detachably connected with the first structural part connecting support through a first angle adjusting hole, and the second adapter plate is detachably connected with the second structural part connecting support through a second angle adjusting hole. The two longitudinal ends of the spot welding cross-shaped structural part are in threaded connection with the first structural part connecting support through bolts, and the two transverse ends of the spot welding cross-shaped structural part are in threaded connection with the second structural part connecting support through bolts. The clamping device has the technical effects of being flexible in angle adjustment, stable and reliable in clamping, high in adaptability, high in efficiency and high in safety.

The invention discloses a tensile fatigue testing device and method, and relates to the technical field of fatigue testing equipment, and the tensile fatigue testing device comprises a first fixing part which is used for connecting a first end of a to-be-tested part; the second fixing piece is movably arranged relative to the first fixing piece, and the second fixing piece is used for being connected with the second end of the to-be-tested piece; the periphery of the first fixing piece and the periphery of the second fixing piece are both provided with the locking assemblies, and the locking assemblies are used for abutting against the end face of the first end of the to-be-tested piece or the end face of the second end of the to-be-tested piece so that the first fixing piece and the second fixing piece can be reinforced relative to the to-be-tested piece; the moving assembly is connected to the second fixing member or the first fixing member and is used for driving the to-be-tested member to move for testing. The end faces of the two ends of the to-be-tested piece are tightly jacked through the locking assembly so as to be matched with the first fixing piece and the second fixing piece to fix the to-be-tested piece, reliable jacking of the to-be-tested piece is further guaranteed, reinforcing of the to-be-tested piece is achieved, and it is guaranteed that the to-be-tested piece is reliable and stable during testing.

The utility model belongs to the technical field of metal material tensile fatigue testing, and particularly relates to a metal material tensile fatigue testing device which comprises a supporting table, an air cylinder, a sliding plate, a fixing plate and guide rails, the two guide rails are fixedly installed on the top of the supporting table, and the fixing plate is fixedly installed on the tops of the two guide rails. The outer sides of the two guide rails are slidably connected with a sliding plate, an air cylinder is fixedly installed on the outer side of the supporting table, the telescopic end of the air cylinder is fixedly connected with the sliding plate, the air cylinder is used for driving the sliding plate to move along the outer sides of the two guide rails, and a clamping assembly is arranged at the position, located between the two guide rails, of the top of the supporting table. According to the utility model, the square groove and the circular groove are formed in the clamp I and the clamp II, so that not only can metal sheets or plates such as automobile damping sheets with fixed shapes be fixed, but also circular pipe fittings or metal columnar materials can be fixed, the detection requirements of common test articles are met, and the use limitation of the device is eliminated.

The utility model relates to the field of sample clamps, and discloses a tension fatigue clamp suitable for round-link chain samples of different specifications, which comprises a protective shell and a chain ring I. The front end of the protective shell is provided with a protective plate, the front end of the protective plate is provided with a grip, and the inner wall of the protective shell is provided with a fixing assembly. A threaded hole is formed in the top end of the protective shell, the fixing assembly comprises a supporting plate, the supporting plate is installed on the inner wall of the protective shell, a left baffle is installed at the front end of the supporting plate, a fixing groove is formed in the front end of the left baffle, a pulling plate is inserted into the inner wall of the fixing groove, and the outer wall of the pulling plate is sleeved with the first chain ring. A fixing plate is installed at the front end of the left baffle. According to the circular chain ring fatigue clamp, the tension fatigue test can be carried out on circular chain samples of different specifications by replacing part of parts, and meanwhile, the whole device is simple in structure, low in cost and high in safety, so that the production and manufacturing cost of the circular chain ring fatigue clamp is reduced.

The present application relates to the field of metal composite plate explosion welding, and provides a sample, a tool and a method for Z-direction fatigue test of an explosion composite joint, the sample comprising at least a top layer and a bottom layer, and the sample comprising at least one interface, the sample comprising: a circumferential boss part composed of an upper part of the top layer; a central column part arranged below the circumferential boss part, the central column part comprising at least a lower part of the top layer and the bottom layer; a tapered transition part arranged between the circumferential boss part and the central column part; an upper central through hole opened downward from the top of the sample and extending to below the interface to be tested by more than 1mm; and a lower central through hole in communication with the upper central through hole. The sample for Z-direction fatigue test of the explosion composite joint, one, controls the fatigue failure surface at the interface, and realizes accurate determination of the Z-direction fatigue performance of the explosion composite joint; two, does not easily cause interface fracture during installation; and three, can satisfy tensile-tensile fatigue, tensile-compressive fatigue and compressive-compressive fatigue tests.

The present application relates to the field of material science and fracture mechanics, in particular to a technical method for characterizing fracture microstructure. Specifically, the present application provides a characterization method for directly obtaining the orientation of cleavage surface of fracture by EBSD technology, which can be used for orientation analysis of smooth cleavage surface or quasi-cleavage surface on the fracture of tensile, fatigue or impact samples. The method realizes direct characterization of cleavage surface by EBSD (electron backscatter diffraction) technology combined with three-dimensional orientation characterization method of fracture, thereby improving the characterization accuracy of micro features of fracture surface, greatly reducing the characterization cost, and realizing visual characterization of the spatial orientation information of the facet by crystallographic calculation.

The utility model discloses an indirect tensile fatigue test clamp. The indirect tensile fatigue test fixture comprises a base for supporting and placing a to-be-tested piece; a guide post is arranged on the base; the measuring table is sleeved on the guide column and moves up and down along the guide column; an opening penetrating up and down is formed in the measuring table, limiting guide rails are arranged on two opposite sides in the opening, and a displacement sensor adjusting structure is arranged on the measuring table above the opening; the pressing block is arranged on the guide column in a sleeving manner, and the pressing block is driven by external force to downwards apply pressure to the to-be-tested piece along the guide column; in the testing process, the displacement sensor adjusting structure makes contact with the to-be-tested piece in the direction perpendicular to the pressure of the pressing block and senses the displacement change of the to-be-tested piece in the direction. The indirect tensile fatigue test clamp has the functions of displacement sensor fixing and test piece guiding, the problems that a traditional displacement sensor fixed to a test piece is tedious in operation and inaccurate in data acquisition are solved, and the test piece can be conveniently guided to be damaged in the loading process.

The utility model relates to the technical field of cable tensile fatigue test, and discloses a cable tensile fatigue test device, which comprises a supporting bottom plate and an adjusting box, fixing sheets are fixed at the top of the supporting bottom plate close to two sides of the adjusting box, and buffer cotton is filled in a buffer pad. The fixing pieces are fixedly installed above the supporting bottom plate, the second installation holes are formed in the fixing pieces, the connecting plates are fixed to the lower portions of the two sides of the protective cover, and the first hook-and-loop fasteners are fixed to the two sides, the front portion and the rear portion of the inner wall of the protective cover. The first hook-and-loop fastener and the second hook-and-loop fastener are matched to complete assembly of the buffer pad in advance, the shaping plate plays a role in shaping the joint, and the buffer pad is filled with the buffer cotton, so that when the broken cable is damaged and fractured, if the cable flies, the protective cover can form protection, and the service life of the cable is prolonged. And through the assembly of the buffer pad, the problem of damage caused by the cable hitting the inner wall of the protective cover is reduced, and the overall safety is improved.

The application discloses a method for predicting the fatigue fracture times of wind turbine blade composite materials, comprising the following steps: preparing a plurality of wind turbine blade composite material samples, each sample being prepared with two parallel test samples; taking one parallel test sample of each sample to perform a creep performance test under preset test conditions; taking another parallel test sample of each sample to perform a fatigue performance test; fitting the relationship between the creep strain and the fatigue fracture times; for the wind turbine blade composite material to be tested, performing a creep performance test under the same test conditions to obtain the creep strain, and according to the obtained relationship, obtaining the predicted fatigue fracture times of the wind turbine blade composite material. The method can complete the fatigue performance test and evaluation in a short time, establish a linear correlation model of creep and fatigue, calculate the fatigue fracture data by testing the creep strain data, and experimental results show that the theoretical calculation data is very close to the data obtained by the tensile fatigue performance test.

The invention discloses a seamless steel tube for a high-strength steering pull rod and a manufacturing method of the seamless steel tube. The seamless steel tube comprises the following components in percentage by weight: 0.12-0.35% of C; 0.1 to 1.0 percent of Si; 0.8 to 1.8 percent of Mn; 0.05 to 0.6 percent of Ni; 0.2 to 0.6 percent of Cr; 0.05 to 0.6 percent of Mo; 0.015% to 0.060% of Al; 0.02 to 0.25 percent of V; 0.015%-0.35% of Nb; the steel comprises the following components in percentage by weight: 0.2-0.8% of Ti, 0.015-0.1% of N, less than or equal to 0.025% of P, less than or equal to 0.015% of S and the balance of Fe and other inevitable impurities, and the elements also need to meet the condition that Ti / N is more than or equal to 2 and less than 0.6 < = (Mn + Cr) / 10 (V + Nb) < = 1.4. The tensile strength of the obtained seamless steel pipe is larger than or equal to 900 MPa, the yield strength is larger than or equal to 750 MPa, the ductility is larger than or equal to 30%, the-60 DEG C low-temperature impact energy is larger than or equal to 100 J, and the number of times of tensile fatigue resistance of cyclic tensile stress between 100 MPa and 500 MPa is larger than or equal to 1 million.