46 results about "Creep stress" patented technology

The invention relates to a low-cycle creep and fatigue life evaluation method under the conditions of high temperature and multiaxial spectrum load. The method comprises the following steps of reading a stress strain history in a multiaxial loading spectrum data block, working out equivalent strain, and finishing a loading history; repeatedly extracting by adopting a relative equivalent strain multi-axis counting method; working out all repeated fatigue damage by adopting a unified multiaxial fatigue damage life prediction model; accumulating the fatigue damage to work out the total fatigue damage; working out equivalent creep stress by utilizing the original loading history; working out creep damage Dc according to the equivalent creep stress and the stress history by combining a creep lasting equation; working out the total damage D caused by a multiaxial load spectrum block at the high temperature; and estimating the multiaxial creep and fatigue life. According to the method, the fatigue damage under the multiaxial stress and the creep damage under the multiaxial stress can be respectively calculated in the whole loading spectrum data block, the fatigue material constant at the room temperature is adopted in the calculation of the fatigue damage, and lasting equation material constant recommended by specification is adopted in the calculation of the creep damage; through experimental verification, the method has a good prediction effect.

The invention provides a method for manufacturing a large-curvature aluminum alloy integral wall board component. The method includes the steps that A, solution hardening is conducted on a wall board; B, the wall board obtained in the step A is arranged in a sealed environment formed by a thin film covering layer and a forming die jointly, the wall board is elastically deformed and plastically deformed in sequence under the vacuumized condition, and then the deformed wall board is obtained, wherein the temperature in the sealed environment where the wall board is located ranges from 15 DEG C to 35 DEG C, the vacuum degree ranges from -0.1 MPa to -0.05 MPa, and the treatment time ranges from 5 min to 60 min; C, in-situ creep stress relaxation aging is conducted on the deformed wall board obtained in the step B, wherein creep stress relaxation aging time is more than 2 h; D, unloading operation is conducted, and then the large-curvature aluminum alloy integral wall board component is obtained. When the method is used for manufacturing the large-curvature aluminum alloy integral wall board component, the residual stress of the product is greatly reduced, the strength of the product is improved, and the product with high forming accuracy and good performance is obtained.

The invention relates to a method for multilevel creep age forming of an Al-Zn-Mg-Cu series aluminium alloy plate. The method is characterized in that a reasonable solid solution-quenching-pretreating-multilevel creep aging system is adopted, is suitable for plates with the thickness of 2 millimeters-30millimeters and comprises the following steps that solid solution is carried out at 470-485 DEG C for 30 minutes-120 minutes, quenching is then carried out, the quenched plate is subjected to 0-10% predeformation treatment and creep aging at 120 DEG C and is thermally insulated for 24 hours, the creep return temperature is between 150 and 170 DEG C, return thermal insulation is carried out for 20-240 minutes, and another creep aging is thermally insulated at 120 DEG C for 24 hours, wherein the creep stress is between 100 and 150 mega pascals, and the forming bending radius is between 800 millimeters and 5000 millimeters. The method is utilized to treat Al-Zn-Mg-Cu series aluminium alloy, so that the alloy creep aging strengthening phase can be effectively regulated, the mechanical property of the alloy plate and the alloy creep formability are improved, the residual stress of the alloy plate is reduced, and the alloy exfoliation corrosion resistance is improved.

The invention relates to a method for creep age forming of an Al-Zn-Mg-Cu series aluminium alloy plate. The method is characterized in that a reasonable solid solution-quenching-pretreating-creep aging system is adopted, is suitable for plates with the thickness of 2 millimeters-30millimeters and comprises the following steps that solid solution is carried out at 470-485 DEG C for 30 minutes-120 minutes, quenching is then carried out, and the quenched plate is subjected to 0-10% predeformation treatment and creep aging at 120 DEG C-150 DEG C and is thermally insulated for 2-36 hours, wherein the creep stress is between 100 and 150 mega pascals, and the forming bending radius is above 1000 millimeters. The method is utilized to treat Al-Zn-Mg-Cu series aluminium alloy, so that the Al-Zn-Mg-Cu series aluminium creep formability can be effectively improved, and the residual stress of the alloy plate is reduced.

The invention discloses a method of computing reinforced concrete creep stress which obtains constraint factors reflecting the actual constraint status of a reinforced concrete structure according to the rebar stress actually measured by a rebar stressometer and further finding the relationship between the reinforced concrete creep stress and the rebar stress. Compared with the method of obtaining the concrete stress through complicated mathematic changes by using buried complicated strainometer and non-stressometer in the prior art, the invention has the advantages of higher accuracy and economy. The invention provides powerful reference for reflecting the status of the internal force of the composite material reinforced concrete and evaluating the safety of the reinforced concrete structure.

The invention relates to a method for designing a salt rock stratum irregular-shaped sleeve. According to different salt rock stratum creep stress states, by changing the inner diameter or outer diameter of the irregular-shaped sleeve, the sleeve cross section shape suitable for a crustal stress level condition is determined. The irregular-shaped sleeve has the following two forms: an inner wall of the sleeve is circular, and an outer wall of the sleeve is oval; and an inner wall of the sleeve is oval, and an outer wall of the sleeve is circular. When the irregular-shaped sleeve is put into a shaft, the position with the maximum wall thickness and the direction of the maximum horizontal crustal stress are uniform. By means of the method, effective stress of a sleeve body under an uneven horizontal crustal stress state can be effectively reduced, the sleeve can be prevented from being damaged, and the technical problem that the strength of the sleeve with the existing wall thickness under the uneven horizontal crustal stress state is not enough and the sleeve can not be kept well in the follow-up production process is solved.

The invention discloses a creep aging forming method for an Al-Cu-Mg series alloy sheet material. The creep aging forming method relates to a heat treatment method for reducing creep aging anisotropy of the Al-Cu-Mg alloy sheet material and improving an alloy performance. The method comprises the following steps of: water quenching after adopting solid-solution treatment at 490-505 DEG C for 30-70 minutes, carrying out 2-10% of predeformation processing on a quenched sheet material, and then carrying out creep aging, wherein a creep temperature is 150-200 DEG C; creep time is 0-12 hours; creep stress is 150-300 MPa, and predeformation processing time is controlled within 4 hours. By adopting the creep aging forming method to process an Al-Cu-Mg alloy, a mechanical property of the alloy sheet material can be improved and a degree of anisotropy of the sheet material can be reduced by controlling precipitation of an alloy creep aging strengthening phase. Compared with common thermal treatment, tensile strength of a room temperature is improved by at least 10%, and the anisotropy is reduced by at least 10% by adopting the creep aging forming method to process the Al-Cu-Mg alloy. The technique is simple in operation, and remarkable in effect. Compared with improvement of alloy microstructure components by a microalloying manner, cost is saved; the method is easy to achieve in industrial production, and comprehensive benefit is obviously higher than that of a reported processing method.

Present invention refers to a method for overcoming salt rock layer creepage utilizing drilling fluid density and chlorides concentration relationship concentration relationship. It contains 1, to make hole boring with sampling and test sample processing, 2, taking four experiment test samples, to proceed creep test to each test sample, taking multiple level temperature and multiple level loading compound experiment mode to obtain creep test straining and timetable, 3, establishing salt rock creepage constitutive relation equation i.e. creep stress-rate of strain relation equation through curve matching method, 4, establishing well bore necked-in rate and drilling fluid density relation equation,5, taking the rest of four test samples, to proceed salting in experiment, corresponded salting in dissolution rate and chlorides pH indicator relation curve, establishing salting in rate and chlorides pH indicator relational model through nonlinear regression, 6, establishing drilling fluid density, temperature and chlorides pH indicator graph of relation edition, determining rational drilling fluid density and chlorides concentration to overcame salt bed creepage according to steps 6 graph of relation edition to salt bed well drilling in same zone block with experiment well core.

The invention provides a concrete support stress monitoring data processing and optimization method; the method can better represent concrete support stress values, can better comply with engineering real conditions, and can provide more reliable construction basis for construction personnel. The method uses a stress correction value [sigma] to determine whether the concrete support is safe or not; the method considers an elastic modulus E changing with time, a contraction stress microstrain [Epsilon]2 formed by the contraction stress, and a creep stress microstrain [Epsilon]3 formed by the creep stress, thus better reflecting the concrete support truly received stress conditions, and providing more reliable construction basis for the construction personnel.

The invention discloses a lever-based slow tensile stress corrosion experimental device. The device comprises a lever balance system, a corrosion test system and a feedback adjustment system; the lever balance system comprises a lever and a lever bracket for supporting the lever; the left end of the lever is connected with the corrosion test system; the right end of the lever is provided with a weight device; the corrosion test system includes an electrochemical corrosion tank; the electrochemical corrosion tank is used for simulating a corrosive environment and fixing a sample; the electrochemical corrosion tank is connected with the left end of the lever; the feedback adjustment system is connected between the lever balance system and the corrosion test system; and the feedback adjustment system is used for adjusting the balance of the lever. According to the lever-based slow tensile stress corrosion experimental device of the invention, the load of the weight can be amplified by thelever structure, and therefore, additional stress on a rod can be reduced; before an experiment is performed, different loads can be loaded or the position of the weight can be moved, and therefore,a variety of creep stress stretching conditions can be provided. The device has the advantages of simplicity and accurate measurement. With the device adopted, the real-time monitoring of creep stressand displacement under a constant force can be realized.

A system and methods for the condition based lifing of a gas turbine engine component is disclosed. The system and methods determine the stress and caused by fatigue and creep for each load cycle of the gas turbine engine, and use a ductility exhaustion method to combine the fatigue and creep strain rates determined from the fatigue and creep stresses to determine the remaining useful of the gas turbine engine component.

The invention discloses a shaft torsional multi-axis variable-amplitude thermo-mechanical fatigue life prediction method based on material critical surface damage. The invention relates to the field of multi-axis thermo-mechanical fatigue strength theories. The method includes calculation of a multi-axis mechanical load cycle count, the critical surface angle of each load cycle, the critical surface pure fatigue damage of each load cycle, the total pure fatigue damage of the critical surfaces, stress on the critical surface of the material, an average differential critical surface load history, the critical surface equivalent creep stress of each section, the critical surface creep damage of each section, total creep damage of all critical surfaces, total non-pure fatigue damage of all critical surfaces, total damage of the critical surfaces and predicted service life. The proposed life prediction method can well predict the fatigue life of the alloy material under the shaft torsionalmulti-axis variable-amplitude thermo-mechanical loading.

The invention relates to a method for reducing longitudinal shrinkage joints of an underground comprehensive pipe gallery. The method is characterized in that the stress change of the pipe gallery section is controlled, specifically, the stress making the underground comprehensive pipe gallery generate cracks is reduced through control over shrinkage stress, temperature stress and creep stress, and therefore, occurrence of the shrinkage joints is reduced; when sigma <ck>- sigma <pc> is smaller than or equal to f<tk>, the longitudinal shrinkage joints can be reduced, the sigma <ck> represents anti-crack edge concrete normal stress, and the sigma <pc> represents anti-crack edge concrete pre-pressure stress; through control over the shrinkage stress and the temperature stress in the construction stage, the purpose of reducing stress is achieved, and therefore, occurrence of the cracks is reduced; and through control over intelligent tensioning and by the adoption of cohesive pre-stressed concrete plates in the long-term maintenance stage, occurrence of the creep stress is reduced, and therefore, occurrence of the cracks is reduced.

The invention discloses a steel bundle tensioning connector and a bridge structure of a simply-supported transformed continuous bridge with a negative bending moment. The steel bundle tensioning connector is directly embedded in the T-beam along the longitudinal direction of the T-beam and tensioned in the wet joint area between the T-beams so that the existing pier top negative bending moment area of the curve steel bundle into a straight bundle, reduce the pipe friction caused by the loss of prestress. On the one hand, it avoids the steel bar breaking in the T-beam, and greatly reduces the influence of the reserved tension groove on the bearing capacity of T-beam, while the tension groove transfers from the top of the precast T-beam wing to the wet joint area. On the other hand, the agedifference of concrete in and around the reserved tensioning groove is greatly shortened, and the shrinkage and creep stress of concrete due to age difference is greatly reduced. From the view of construction process, the construction procedure of tensioning steel bundle is adjusted from tensioning before anchoring to anchoring before tensioning, which eliminates the prestress loss caused by the retraction of anchorage.

The invention discloses a digitalized construction site concrete prediction type anti-cracking method which comprises the following steps: firstly, arranging a temperature and stress sensor at a concrete sensitive position, then endowing concrete with a thermal parameter initial value, and then feeding back and analyzing a concrete thermodynamic parameter based on a particle swarm algorithm; calculating internal temperature predicted value and a stress predicted value in future 4-7 days according to a control equation of a three-dimensional unstable temperature field and a control equation ofa creep stress field; and finally, taking anti-cracking measures on the mass concrete according to the solved stress prediction value. According to the method provided by the invention, the calculation result is more accurate, and the concrete anti-cracking measure is adjusted according to the predicted future concrete temperature and stress development trend, so that the anti-cracking effect is the best.

The invention discloses a high-temperature-resistant and high-pressure-resistant creep die-casting magnesium alloy and a preparation method thereof and belongs to the technical field of magnesium alloys. The problem that the creep resistance of the magnesium alloy in the prior art cannot completely meet the use requirement in the environment at the temperature of 200 DEG C or above is solved. The magnesium alloy comprises the following components including by weight, 1% to 6% of Zn, 0.5% to 4% of La, 0.5% to 6% of Y, 0% to 0.5% of Zr, 0% to 0.5% of Mn and the balance magnesium and inevitable impurity elements. The magnesium alloy contains Zn, La and Y, the Zn, the La and the Y form a continuous net-shaped second-phase structure in three-dimensional space distribution after being melted, a second phase has multiple structures, dislocation slippage and twin crystal formation can be effectively hindered under the high-temperature condition, the high-temperature creep resistance of the alloy is improved, it is verified that at the temperature of 250 DEG C, the creep stress of the alloy is 80 MPa, the lasting creep life is longer than 300 h, and the steady-state creep rate is less than 6*10<-9>/s.

The invention provides a turbine rotor creep damage real-time calculation method based on a finite element model. The turbine rotor creep damage real-time calculation method comprises the steps that atemperature field and a stress field of a rotor are calculated through finite element analysis software; Extracting temperature and stress data of the key part; Performing normalization processing ontemperature, pressure, rotating speed and stress data related to creep damage calculation; Establishing a creep stress real-time calculation model by adopting a multivariate regression method; Analyzing and fitting stress; Calculating a damage function relationship, and calculating creep damage in real time; And establishing a creep damage real-time calculation system structure. The problem of real-time calculation of rotor creep damage in the prior art can be solved, and the method has high precision.

The invention discloses a cement-based material axial pressure creep testing device capable of regulating and controlling temperature, humidity and load. The cement-based material axial pressure creep testing device comprises: an integral testing framework, wherein the integral testing framework consists of a fixed steel frame, a bearing support column, a bearing lever, a protecting device, a stabilizing device, bolts and the like; an axial pressure load regulation and control system composed of a slidable connecting device, a dead load counterweight device and a force transmission device; a test condition control system consisting of a temperature regulation and control device and a humidity regulation and control device; and a creep data acquisition and recording system consisting of a cement-based material sample, an axial pressure deformation measuring device and a data transmission and acquisition device. According to the invention, after a test piece and a deformation testing device are installed, the position of a bearing support column is adjusted, a counterweightblock matched with creep stress needed for testing is placed on a bearing tray, the needed temperature and humidity are set, and finally the temperature and humidity change is checked regularly and the creep degree progress is recorded; and the whole axial pressure creep testing device and method are simple and easy to implement, and the deformation characteristics of the cement-based material under various temperature and humidity and different creep stresses can be obtained.

The invention relates to the technical field of rock physical and mechanical property testing, and discloses a rock long-term strength determination method based on dominant acoustic emission seismic source energy characteristics, which comprises the following steps: carrying out longitudinal wave velocity testing on a standard rock test piece, arranging an acoustic emission sensor on the standard rock test piece; carrying out graded creep failure acoustic emission seismic source positioning test on the standard rock test piece, calculating P wave arrival time and initial motion amplitude corresponding to each acoustic emission seismic source, solving a moment tensor corresponding to each acoustic emission seismic source, classifying the acoustic emission seismic sources according to moment tensor characteristic values, and determining dominant acoustic emission seismic sources; picking up absolute energy of each stage of dominant acoustic emission source, calculating an absolute energy average value of each stage of creep dominant acoustic emission source, and drawing an absolute energy average value-creep stress curve; and taking a creep stress average value corresponding to the lowest point on the absolute energy-creep stress curve and a first data point after the lowest point as a rock average value being long-term strength sigma infinity.

The invention provides a method for testing the creep property of metal. The method comprises the following steps: after loading initial axial stress to a sample, sequentially increasing the axial stress which is the same as the initial axial stress at the same time interval until the sample is broken; then, collecting stress and strain data in real time through a weighing sensor and a linear variable differential transformer, transmitting the data to a computer, processing the data through software, and drawing a creep curve of the sample; obtaining the minimum creep rate by utilizing the obtained creep curve, and drawing a minimum creep rate creep stress logarithm diagram according to a power law formula to obtain a creep index. According to the test method provided by the invention, the problems of more samples and long test time used for testing the metal creep property can be solved.