127 results about "Fatigue limit" patented technology

The invention discloses a crane stress monitoring data processing method and system, and solves the technical problem that real-time online analysis of stress monitoring big data is difficult to realize due to lack of a crane intermittent stress monitoring big data processing method in the prior art. The method comprises the following steps: acquiring stress monitoring data through a crane stress monitoring system; eliminating stress abnormal values; extracting and separating trend terms of the monitoring data to obtain new monitoring data; segmenting the new monitoring data according to the time of one working cycle of the crane to obtain segmented monitoring data; calculating the difference value between the maximum stress value and the minimum stress value of the segmented monitoring data, and assuming that the fatigue limit of the material is Sf, and the threshold value of the stress amplitude Sa is 5% of Sf; and judging whether the stress monitoring data of the section needs to be stored / remotely transmitted or not. According to the method, the calculation requirement is low, whether the crane causes the fatigue accumulated damage state or not can be effectively judged, and the stress monitoring big data storage / transmission capacity is greatly reduced.

The invention discloses a method and device for predicting the fatigue life of a high-temperature alloy vacuum electron beam welding structure, and belongs to the technical field of aero-engines. The method comprises the following steps: acquiring fatigue experiment data of a target high-temperature alloy standard sample; extracting the maximum area of an initial defect, a defect shape factor and crack source position information; obtaining a stress intensity factor range considering defect morphological characteristics and a fatigue crack propagation threshold value of a material structure containing initial defects, and correcting a damage tolerance theoretical formula to obtain simulation data; fatigue test data and simulation data are fused to form an initial data set, a fatigue limit is calculated and expanded to the data set, the expanded data set serves as input, training is conducted through a support vector regression method, hyper-parameters are determined through Bayesian optimization, and a fatigue life prediction result of the high-temperature alloy vacuum electron beam welding structure is output. The method provided by the invention can well consider the influence of different morphology defects on the fatigue performance of the welded joint.

The invention provides an aero-engine blade high-cycle fatigue limit prediction method, which comprises the following steps: firstly, performing parameter measurement based on an impact-corrosion coupling damaged blade, calculating to obtain a fractal dimension and a stress concentration coefficient, and correcting equivalent stress by using the fractal dimension and the stress concentration coefficient to obtain a corrected critical distance model; and utilizing the corrected critical distance model to predict and calculate the fatigue limit of the coupling damaged blade. According to the blade high-cycle fatigue limit prediction method provided by the invention, the three-dimensional fractal dimension, the theoretical stress concentration coefficient and the stress gradient distribution function near the root of the notch are creatively integrated into the same model, and the blade fatigue limit obtained through prediction and calculation is highly consistent with the measured value of the test.

The present invention relates to a fatigue-resistant and corrosion-resistant 500 MPa-grade steel plate for marine wind power, the chemical composition of which is as follows, by mass percentage: C: 0.10%-0.12%, Si: 0.20%-0.30%, Mn: 1.20%-1.40%, P≤0.010%, S≤0.005%, Nb: 0.030%-0.040%, Ti: 0.018%-0.030%, Ni: 0.28%-0.38%, Cu: 0.35%-0.55%, Al: 0.020%-0.050%, Pcm being controlled to be ≤0.25%, and the remainder being Fe and unavoidable impurity elements. The 500 MPa-grade steel plate for marine wind power of the present invention is produced using a TMCP+tempering process, and has a thickness of 30 mm-60 mm, a yield strength of ≥500 MPa, a tensile strength of 600-760 MPa, an elongation after fracture of ≥17%, and a core impact energy of ≥120 J at -30℃. Corrosion resistance is improved by 50% or more compared with conventional 355 MPa-grade steel plate for marine wind power. After the steel plate is welded by submerged arc welding with a heat input of ≥35 kJ / cm, the tensile strength of the welded joint is ≥600 MPa, and the impact energy at -30℃ is ≥80 J; under conditions of a stress ratio of 0.5, the fatigue limit of a welded joint after 107 cycles of axial loading is ≥450 MPa. The steel has the characteristics of high strength, fatigue resistance, corrosion resistance and easy welding, and can meet the development requirements of safe service, high strength and light weight for marine wind power facilities.

The invention discloses a welding wire for 780 MPa grade wheel steel and a laser-arc hybrid welding process. The welding wire comprises the following chemical components in percentage by weight: 0.06%-0.08% of C, 0.30%-0.80% of Si, 1.80%-2.0% of Mn, 1.5%-2.0% of Ni, 0.20%-0.50% of Cu, 0.20%-0.50% of Mo, 0.04%-0.07% of Nb, 0.06%-0.10% of Ti, 0.03%-0.07% of V, 0.015%-0.10% of RE, less than or equal to 0.010% of S, less than or equal to 0.010% of P and the balance of Fe and inevitable impurities. A welding joint obtained through the welding wire and the process has good mechanical performance, the strength coefficient of the joint is 1.0, the impact absorption energy at the temperature of-20 DEG C is larger than or equal to 120 J, the fatigue limit sigma 0.1b is larger than or equal to 740 MPa, and the structures of a weld zone are mainly acicular ferrite, bainite and a small amount of proeutectoid ferrite.

The invention discloses a method for predicting the ultra-high-cycle multi-axis tension-torsion composite variable-amplitude fatigue life of a titanium alloy. The method relates to data acquisition, processing and life calculation of ultra-high-cycle uniaxial fatigue tests under three different stress ratios, ultra-high-cycle multi-axial fatigue tests with different shear / axial stress ratios under symmetrical circulation and ultra-high-cycle multi-axial tension-torsion composite variable-amplitude fatigue tests. A stress ratio correction model in the ultra-high cycle field is established based on a Goodman equation, a new multi-axis parameter is introduced to replace a shear / axial stress ratio, and a shear stress influence factor is proposed to correct Mises equivalent stress which is suitable for fatigue limit equivalence. By analyzing a new multi-axis parameter, a shear stress influence factor in a fatigue limit under different shear / axial stress ratios and a relationship between an S-N curve slope and a fatigue index in a Basquin equation, actual tests verify that the calculation is simple and convenient, the accuracy is high, and the method has great practical significance.

The invention relates to a fatigue limit rapid prediction method based on infrared thermal image energy dissipation characteristics. The method comprises the steps of sample preparation and pretreatment, fatigue loading stress level upper limit determination, infrared fatigue test and temperature rise data acquisition, thermal image data processing and temperature rise feature extraction, energy dissipation model construction, fatigue limit value prediction, error analysis and method verification. The method comprises the following steps: monitoring steady-state temperature rise rates under different stresses through a thermal infrared imager, establishing a relation curve between a dissipation rate and a stress amplitude, predicting a fatigue limit based on a least square method, and comparing the fatigue limit with an S-N test result for verification. Compared with a traditional method, the method has the advantages of high prediction precision, high response sensitivity, low loss, short test period and the like, and is particularly suitable for rapid fatigue limit prediction and strengthening effect judgment of the high-temperature alloy material subjected to laser-assisted ultrasonic rolling strengthening.

The invention provides a blade high-cycle fatigue limit prediction method considering corrosion damage, which comprises the following steps: carrying out simulation modeling and processing according to a real blade to obtain a simulated blade, placing the real blade and the simulated blade in a constant-temperature corrosion solution to simulate the corrosion condition of the blade under a real working condition, obtaining blades with different corrosion durations, and carrying out high-cycle fatigue limit prediction on the blade after obtaining the blades with different corrosion durations. Performing stress-strain curve measurement and fatigue limit test on the blade, and fitting according to fatigue limit data to obtain a prediction curve of corrosion time and fatigue limit; the invention provides the method for simulating the blade corrosion condition and predicting the fatigue limit of the blade under the laboratory condition, and compared with the fatigue limit prediction of the traditional theoretical calculation and empirical formula, the fatigue limit of the blade closer to the real working condition can be obtained.

A U-shaped bolt fatigue test device comprises bases in bilateral symmetry and plate springs supported on the bases on the two sides, bearing rollers capable of freely rotating are arranged at the two ends of each plate spring respectively, the bearing rollers at the ends are rotationally supported on the bases correspondingly, the center of each plate spring protrudes upwards, and a connecting block is fixed to each plate spring through a plurality of U-shaped bolts and nuts. And the plate spring penetrates through each U-shaped bolt. The U-shaped bolt fatigue testing device can be conveniently connected with an MTS servo testing machine, a road spectrum is applied by the servo machine when an automobile runs, and a plate spring is driven to move up and down, so that the stress state of the U-shaped bolt in actual work and the torque change of a nut are simulated, the fatigue limit value of the U-shaped bolt is further obtained, the experimental result is almost free of deviation, and the measured data are more accurate and reliable.

The invention discloses a method for cooperatively regulating and controlling the microstructure and fatigue resistance of a GH4169 alloy based on LPBF, and belongs to the field of metal additive manufacturing. Through multi-dimensional collaborative innovation such as LaZrO core-shell nano-composite strengthening phase design, dynamic energy input and intelligent regulation and control, grain boundary engineering and precipitated phase collaborative optimization and graded green post-treatment, the problems that when a GH4169 alloy part is prepared through a traditional LPBF technology, grains are coarse and large, the number of internal defects is large, and the fatigue performance is insufficient are solved. The breakthrough achievements that isometric crystals are ultra-refined (3-10 microns), the defect rate is reduced by more than 50% and the room-temperature high-cycle fatigue limit is improved by 38% are achieved, meanwhile, the green manufacturing requirement is met, and a high-performance and high-reliability complex part manufacturing solution is provided for the fields of aerospace and the like.

The invention provides an additive repair blade high-cycle fatigue limit prediction method based on random defect probability distribution, and relates to the field of aero-engine fan and compressor blade maintenance, and the method comprises the steps: obtaining the defect distribution of a real blade; establishing a prediction model based on a critical distance theory; according to the prediction model, critical distances of the multiple real blades are determined, and a first critical distance is generated; performing defect reconstruction based on the defect distribution of the real blade to generate a virtual blade; obtaining the first high-cycle fatigue strength of the virtual blade according to the defect distribution of the virtual blade, the first critical distance and the prediction model; respectively determining a plurality of defect parameters and a Pearson coefficient of the first high-cycle fatigue strength, and screening a first parameter significantly related to the first high-cycle fatigue strength; constructing a fatigue strength evaluation model; and inputting the first parameter into the trained fatigue strength evaluation model, and outputting the predicted high-cycle fatigue strength. According to the scheme, the high-cycle fatigue limit of the blade can be quickly predicted, and the prediction accuracy is improved.

The invention belongs to the technical field of titanium alloy machining, and relates to a TC4 titanium alloy bar for a high-performance blade and a preparation method of the TC4 titanium alloy bar. According to the method, all raw materials are mixed and pressed into an electrode, and qualified TC4 titanium alloy cast ingots are obtained through three times of VAR smelting; then, the TC4 titanium alloy cast ingot is subjected to multi-heating-number upsetting and drawing forging above and below the phase transformation point to form an intermediate bar blank A; rolling the intermediate bar blank A for multiple heating numbers to obtain an intermediate bar blank B; and finally, surface defects and oxide skin of the middle bar billet B are removed, and the TC4 titanium alloy finished bar for the high-performance blade is obtained. According to the TC4 titanium alloy bar prepared through the preparation method, the primary alpha phase content is larger than or equal to 65%, the average grain size of the alpha phase is smaller than or equal to 15 micrometers, and the room-temperature tensile strength, the room-temperature impact energy, the 400-DEG C high-temperature tensile strength, the 400-DEG C / 350 MPa / 100 h creep plasticity elongation and the fatigue limit that the room-temperature smooth high-cycle fatigue cycle number is larger than 1.0 * 10 < 7 > can all meet relevant standard requirements.

The invention discloses a method for rapidly measuring the fatigue limit of a composite material through an infrared thermography method, and belongs to the technical field of composite material inspection. According to the method, the problems that an existing method lacks definite physical significance and obvious temperature rise is difficult to detect are solved, the temperature change of the surface of the composite material is captured through the thermal infrared imager, the relation between the temperature change and the stress level is analyzed, and the dissipation mechanism of the composite material in the elastic stage and the plastic stage can be effectively distinguished; the fatigue limit of the material can be quantitatively determined through linear fitting and intersection calculation by taking the elastic limit as a boundary and combining an inherent dissipation theory and a fatigue damage mechanism, so that inflection point determination has clear physical significance, and the fatigue limit can be accurately determined in a short time; in addition, by means of the non-contact characteristic of the method, physical damage to the samples is reduced, the repeatability and reliability of the experiment are improved, meanwhile, the number of the samples is reduced, the experiment time is shortened, and the experiment cost and time are reduced.

Disclosed are a wire rod and a steel wire for a spring, a spring with improved strength and fatigue limit, and a method for manufacturing the same. The disclosed wire rod for a spring with improved strength and fatigue limit according to an embodiment includes, in percent by weight (wt%): 0.6 to 0.7% of C, 2.0 to 2.5% of Si, 0.2 to 0.7% of Mn, 0.9 to 1.5% of Cr, 0.015% or less of P, 0.01% or less of S, 0.01% or less of Al, 0.01% or less of N, 0.25% or less of Mo, 0.25% or less of W, 0.05% to 0.2% of V, 0.05% or less of Nb, and the balance of Fe and unavoidable impurities, wherein Mn+Cr≤1.8% and 0.05 at%≤Mo+W≤0.15 at% may be satisfied.

The application provides an aero-engine blade high-cycle fatigue limit prediction method, first, parameters of a blade subjected to impact-corrosion coupling damage are measured, a fractal dimension and a stress concentration coefficient are calculated, the equivalent stress is corrected by using the fractal dimension and the stress concentration coefficient, a corrected critical distance model is obtained, and the fatigue limit of the blade subjected to coupling damage is predicted and calculated by using the corrected critical distance model. The blade high-cycle fatigue limit prediction method provided by the application innovatively integrates the three-dimensional fractal dimension, the theoretical stress concentration coefficient and the stress gradient distribution function near the notch root into the same model, and the blade fatigue limit obtained by the prediction calculation is highly consistent with the measured value of the test.

The application provides an aero-engine blade fatigue failure analysis method, first, the foreign object damage morphology data of the real blade is collected to form a real blade database, then the design parameters of the simulation blade are obtained according to the morphology and stress distribution of the real blade, and then the finite element model of the simulation blade is established, the modal calculation is carried out, whether the inherent frequency of each order mode meets the set requirement is verified, if the set requirement is met, the foreign object damage simulation of the finite element model of the simulation blade is carried out, the simulation result is obtained, and the consistency verification is carried out with the real blade database, finally, the real model of the simulation blade is made, the FOD test and the HCF test are continuously carried out on the real model of the simulation blade, and the fatigue limit of the real model of the simulation blade after damage is obtained. The method takes the foreign object damage morphology data of the real blade as the reference, realizes the high-cycle fatigue limit test of the foreign object damage simulation blade which is closer to the real working condition, has low cost, high controllability of parameters, and good interpretability.

The present invention discloses a method for predicting the life of a roll based on the hardness of a roll, comprising: establishing a mathematical relationship between the hardness of a roll and the life of a roll; obtaining the fatigue limit N1 of the roll under an alternating stress P1 when the roll has an initial Shore hardness Hs0 according to the mathematical relationship; and obtaining the Shore hardness Hs1 of the roll used for n1 times according to the fatigue damage accumulation hypothesis and the mathematical relationship; and obtaining the Shore hardness Hs2 of the roll under an alternating stress P1 by analogy. k Next and loop using n k The Shore hardness of the roller after the rolling process is Hs k ; Finally, the mathematical relationship between the Shore hardness of the roller and different alternating stresses and the number of cycles is derived. The method of the present invention studies the relationship between the Shore hardness of the roller and the fatigue life of the roller, thereby extending the life of the roller by improving the hardness of the roller, thereby reducing the production cost of the enterprise; the prediction result of the prediction method of the present invention is less different from the actual result, which proves that the prediction method of the present invention has a good prediction effect.

The invention provides a method for calculating the fatigue limit of an aluminum alloy by utilizing defects and yield strength, which comprises the following steps: S1, obtaining the yield strength of the aluminum alloy by utilizing a tensile test; s2, a fatigue test is utilized, a large load is loaded, the sample is broken within 2 hours, and a fatigue fracture is obtained; s3, observing a fatigue crack source, and measuring the defect area and the like of the crack source; s4, according to the results of the steps S1 and S3, calculating the fatigue limit by using a mathematical relationship between the yield strength, the defect area and the like and the fatigue limit to obtain a first fatigue strength value; s5, repeating the steps S2, S3 and S4 to obtain a second fatigue strength value; repeating the steps S2, S3 and S4 again to obtain a third fatigue strength value; and by parity of reasoning, after three or more fatigue strength values are obtained, an average value, namely the fatigue limit, is obtained. The method has the beneficial effects that the defect and the yield strength are comprehensively considered, the accuracy of the calculated fatigue limit is higher, and time, manpower and material resources are saved.

This invention provides a novel vibration fatigue testing method for gas turbine blades. Addressing the problems of large specimen wear, long testing time, and limited results associated with traditional step-and-step stress loading methods for obtaining blade fatigue limits, this invention excites blade resonance on an electromagnetic vibration table using novel step-and-step stress loading techniques on identical blade specimens. While retaining the step-and-step matching standard, when limited test data cannot meet the matching requirements, a stress "concession" method is rationally applied based on the turbine blade structure and fatigue strength level to eliminate test data with significant stress deviations, thereby obtaining the median fatigue strength of blades from the same batch. This invention makes stress matching faster and more flexible, requiring only 2-3 stress levels to achieve a test fitting result with a confidence level of over 95%, demonstrating high accuracy. This method is applicable to fatigue limit tests of all gas turbine blades.

The invention provides a magnesium alloy with low cost and high service performance and a preparation method. The preparation method comprises the following steps: uniformly mixing Ti powder and BN powder as well as Nb powder and B4C powder in different proportions to obtain two types of mixtures, and uniformly mixing the two types of mixtures with Al powder in different proportions to obtain a nano precursor; placing the nano precursor in an aluminum tube and a stainless steel tube layer by layer according to a certain mass ratio, and sealing to obtain an aluminum-coated wire and a stainless steel-coated wire; the stainless steel wrapped wire is subjected to induction heating reaction and then the stainless steel skin is stripped to obtain the nano reinforcing agent wire; in the smelting process of the magnesium alloy, an aluminum-coated wire and a nano reinforcing agent wire are added at the same time according to a certain mass ratio, then homogenization, hot extrusion and annealing treatment are conducted, and finally the magnesium alloy with the low cost and the high service performance is obtained. The ultimate fatigue strength of the magnesium alloy is larger than or equal to 130 MPa and is improved by 25% or above compared with that of commercial magnesium alloy, and the fatigue life is prolonged by 12 times or above.

A needle for a warp knitting machine, manufactured by means of an amorphous alloy injection molding process and comprising the following components: in parts by weight, 57.5-65.5 parts of zirconium, 11-16 parts of copper, 7-13 parts of nickel, 5-10 parts of titanium, 1-7 parts of aluminum, 1-7 parts of beryllium and 0.3-2 parts of yttrium. A method for manufacturing a needle for a warp knitting machine by means of an amorphous alloy injection molding process, comprising the following steps: (1) material mixing and smelting for manufacture into small blocks; (2) injection molding; (3) alloy opening removal; (4) thickness machining; (5) slotting; (6) polishing; and (7) electroplating. Beryllium and yttrium are added into amorphous alloy zirconium-based metal; beryllium can improve the toughness of a latch needle product, and has high fatigue limit and high wear resistance; yttrium powder can improve the strength, toughness and wear resistance of a latch needle blank.

The invention discloses a casting molding method for an aluminum piston side drainage runner of a large combustion chamber of an engine, and relates to the technical field of engine piston manufacturing. According to the casting forming method for the aluminum piston side drainage runner of the large combustion chamber of the engine, silicon is added to form an eutectic silicon network, the liquidity of molten aluminum is improved, the grain size is refined, copper and magnesium are added to improve the tensile strength, nickel is matched to inhibit high-temperature creep, the casting speed and the casting pressure are controlled at different casting stages, and the casting quality is guaranteed; in the casting process, ultrasonic vibration is carried out, grains are further refined, semi-solid feeding is promoted, a rotating magnetic field drives casting liquid to carry out spiral mold filling, the gas entrapment tendency is reduced, axial flowing of the casting liquid is promoted, turbulent flow is reduced, the grain size is refined in cooperation with a pulsed electric field, the microshrinkage porosity of the root of a runner is reduced, and the fatigue limit of the root of the runner is improved; the heat resistance, wear resistance and thermal fatigue resistance of the piston are improved, so that the performance of the piston is optimized to prolong the service life of the piston.

The invention relates to the technical field of fatigue testing, and discloses a fatigue experiment device for axle production, which comprises two racks, an annular chain conveying piece is arranged between the two racks, lifting cushion tables are arranged on the surface of the annular chain conveying piece in an array manner, a supporting assembly is slidably connected to the racks, and the supporting assembly is provided with a plurality of clamping grooves. An intermittent rotating assembly is fixedly installed at the right end of the annular chain conveying piece, a reciprocating moving assembly is arranged between the left side of the intermittent rotating assembly and the supporting assembly, an arch-shaped frame is fixedly installed between the tops of the two racks, and two axle suspension assemblies are fixedly installed on the top wall of the arch-shaped frame. The sliding frame is stably supported through the wave part, the cushion platform body is prevented from falling during wheel collision, a firm bumpy road surface is simulated, and therefore the chain body rotates anticlockwise, the relative positions of the wave part and the axle are continuously switched, the bumpy road surface is continuously simulated, long-time detection of the axle is facilitated, and the fatigue limit of the axle is conveniently measured.

The present invention belongs to the field of aeroengines, and relates to a technique for evaluating the strength of a lock piece in a rotor balancing screw. A method and system for evaluating the strength of a lock piece in a rotor connection structure are disclosed, and the method includes: performing an elastic-plastic analysis on an initial lock piece finite element model constructed, and correcting the initial lock piece finite element model according to the result of the elastic-plastic analysis to obtain a lock piece finite element model; constructing a non-warping finite element model and a warping finite element model of a rotor connection structure through the lock piece finite element model, a screw and a matrix, and obtaining the stress of the bending part of the positioning claw in the non-warping finite element model and the stress of the lock piece at the root of the screw pressing in the warping finite element model under working conditions; and evaluating the strength reserve of the lock piece according to the measured tensile properties of the lock piece, the fatigue limit of the lock piece, the results of the elastic-plastic analysis, the stress of the bending part of the positioning claw and the stress of the lock piece at the root of the screw pressing. The present invention can realize accurate evaluation of the risk of the lock piece under working conditions, and provide data guidance for the reasonable design of the lock piece.

The present invention provides a method for preparing a high-modulus, high-strength, and high-fatigue-resistant aluminum-based composite sheet. The method comprises subjecting an in-situ ceramic particle-reinforced aluminum-based composite material to a sequential semi-continuous casting, hot rolling, cold rolling, solution treatment, cold rolling, and aging treatment. The method for preparing the aluminum-based composite sheet provided by the present invention features a simple and rational process. The non-uniform distribution of in-situ ceramic particles forms a two-stage heterogeneous structure with a non-uniform grain distribution, achieving a multi-layered reinforcement structure and a microstructure that inhibits fatigue crack propagation. This method simultaneously improves the elastic modulus, tensile strength, fatigue limit strength, and fatigue crack propagation resistance of the aluminum-based composite sheet, and can be industrially produced using existing industrial equipment.

The application discloses a valve box processing method, comprising the following steps: S1, rough machining of a pressure pump valve box forge blank; S2, normalizing treatment; S3, first tempering treatment; S4, carbonitriding treatment; S5, precooling quenching treatment; S6, second tempering treatment; and S7, packaging. The application simultaneously permeates carbon and nitrogen into the workpiece in the form of carbonitriding to form a carbonitriding layer, on the one hand, carbon atoms enter the metal surface and combine with metal atoms to form carbide, thereby improving the hardness and wear resistance of the workpiece surface, and wear and scratches on the metal surface can be effectively prevented; on the other hand, the permeation of nitrogen forms a dense nitride layer on the workpiece surface, improves the corrosion resistance, and enables the workpiece to be applicable to a harsh environment during oil exploitation; and on the third aspect, the residual compressive stress of the carbonitriding layer can improve the fatigue limit of the workpiece, thereby improving the fatigue strength of the workpiece and reducing brittleness.

The present invention relates to a step cyclic loading rejuvenation method for bulk metallic glasses, comprising the following steps: 1) processing the metallic glass into a specimen capable of cyclic loading treatment; 2) installing the specimen on a cyclic loading device and performing step cyclic loading treatment with an alternating load. The step cyclic loading treatment starts from an initial stress amplitude lower than the fatigue limit, and after a certain number of cyclic loading times, the step stress amplitude is increased for cyclic loading until before the specimen fractures. Compared with the prior art, the method of the present invention has high efficiency, simple process and strong universality, and has good application prospects for regulating the energy state and properties of the structure of metallic glasses.

The invention provides a gas turbine compressor blade service life evaluation method based on high-cycle fatigue characteristics, and aims to solve the problem that fatigue tests under pure simulation and laboratory conditions cannot be effectively combined to meet the requirement of gas turbine blade type core component service life evaluation. According to the method, the strength condition and the vibration condition of the blade are determined through finite element analysis, then the stable attenuation law of the fatigue strength of the blade is obtained by actually measuring the vibration stress and the fatigue limit values of the blade in different use time periods, and the service life of the gas turbine compressor blade is comprehensively evaluated by taking the high-cycle vibration fatigue reserve as the standard. The method is not limited to a ship gas turbine compressor, is also suitable for effective evaluation of the service life of the moving blades of an industrial gas turbine and an aero-engine compressor, and can provide a fatigue reliability design direction for a new model.

The invention discloses a high-fatigue TC4 titanium alloy fine-grain bar for a blade and a preparation method of the high-fatigue TC4 titanium alloy fine-grain bar, and belongs to the technical field of titanium alloy machining. According to the method, firstly, a qualified TC4 titanium alloy cast ingot is obtained through three times of VAR smelting; secondly, the cast ingot is subjected to upsetting and drawing forging at the upper and lower heating numbers at the phase transformation point to obtain a middle bar blank A; then the intermediate bar blank A is subjected to short-time-space water boiling cold and heat treatment above the phase transformation point, and an intermediate bar blank B is obtained; performing low-temperature rolling on the intermediate bar billet B to obtain an intermediate bar billet C; then carrying out medium-high temperature finish machining on the intermediate bar billet C to obtain a target bar billet D; and finally, surface defects and oxide skin of the target bar blank D are removed, the high-fatigue TC4 titanium alloy fine-grain bar for the blade is obtained, and the bar has high-temperature strength and heat stability while the excellent fatigue performance (the room-temperature smooth high-cycle fatigue cycle number is larger than 1.0 * 10 < 7 > times, and the fatigue limit is larger than or equal to 600 MPa) is guaranteed.

The present invention provides a vibration fatigue resistance design method for a helicopter secondary load-bearing structure, the method comprising: applying a vertical unit acceleration excitation to an installation platform to obtain a stress frequency response curve of a secondary load-bearing structure member; based on the frequency response curve, determining a first resonance main peak and a first frequency value corresponding to the first resonance main peak, and determining a dangerous part based on the first frequency value; based on an S-N curve of a structural material at the dangerous part, determining a fatigue limit value of the structural material; based on the fatigue limit value and a helicopter vibration environment spectrum, obtaining a maximum allowable transfer function; the present invention proposes a vibration fatigue resistance design process and method for a helicopter secondary load-bearing structure, analyzing the vibration fatigue strength of the secondary load-bearing member under a vibration environment and optimizing the structure to ensure that the structure meets strength and use requirements.