347 results about "Low-cycle fatigue" patented technology

The invention relates to a damage calculation method for low-cycle fatigue and high-strength impact coupling based on a local stress strain method. The damage calculation method comprises the following steps of: (1) analyzing a fatigue load spectrum, calculating nominal stress strain of each stage of multiple stages of amplitude-variable fatigue load spectra, and converting the nominal stress strain into local stress strain; (2) calculating fatigue life and damage corresponding to each stage of fatigue load local strain when a product is impacted; (3) calculating the fatigue life and the damage corresponding to each stage of the fatigue load local strain when the product is impacted and the impact is in an influence range, and considering the damage probability in a fatigue circulation unit when the product is impacted; (4) calculating impact performance influenced by fatigue accumulated damage; and (5) calculating comprehensive degree of reliability. Compared with a conventional fatigue damage calculation method, the damage calculation method has the advantages that the influence of high-strength impact on the fatigue damage, the influence of fracture failure caused by direct impact to the life of the product and the influence of the fatigue accumulated damage to the shock resistance of the product are considered, and the fatigue-impact life and the degree of reliability of the product can be well evaluated under a complex environment.

A gamma prime precipitation-strengthened nickel-base superalloy and method of forging an article from the superalloy to promote a low cycle fatigue resistance and high temperature dwell behavior of the article. The superalloy has a composition of, by weight, 16.0-22.4% cobalt, 6.6-14.3% chromium, 2.6-4.8% aluminum, 2.4-4.6% titanium, 1.4-3.5% tantalum, 0.9-3.0% niobium, 1.9-4.0% tungsten, 1.9-3.9% molybdenum, 0.0-2.5% rhenium, greater than 0.05% carbon, at least 0.1% hafnium, 0.02-0.10% boron, 0.03-0.10% zirconium, the balance nickel and incidental impurities. A billet is formed of the superalloy and worked at a temperature below the gamma prime solvus temperature of the superalloy so as to form a worked article, which is then heat treated above the gamma prime solvus temperature of the superalloy to uniformly coarsen the grains of the article, after which the article is cooled to reprecipitate gamma prime. The article has an average grain size of not coarser than ASTM 7 and is substantially free of critical grain growth.

A mounting assembly for a heat exchanger for a gas turbine engine. The heat exchanger assembly includes a plurality of arcuate manifolds each supporting an array of fins extending from a radial inner surface. A plurality of circumferentially extending spaced weld tabs is integrally formed on the radial outer surface. A bracket assembly is utilized to attach the heat exchanger to a structural member of a gas turbine engine assembly, e.g., a fan case, in such a manner as to maximize the surface area available for fin placement, and to not interfere with the cooling circuits within the manifold. The mounting system provides adequate stiffness for high cycle fatigue loads (i.e., vibrations) and allows relative slippage between the heat exchanger and the fan case to accommodate thermal expansion and contraction to address low cycle fatigue loads.

It relates to a turbine rotor low cycle fatigue durability loss on line monitoring system, featuring in its computation, application server and software, database server, outside system interface, turbine control system DEH and parameter testing point, web server and user browser that connects with the computation and application server and each end item user browser respectively, with the computation and application server connecting with the data base server which connects with the turbine control system DEH and parameter testing point through the outside system interface. It is made of two processes, with the no.1 using artificial nerve network to determine turbine rotor equivalent stress coefficient, the no.2 process being on line computation, monitoring and control of the turbine rotor cycle fatigue loss. It realizes the working times of the turbine rotor of 10000 times.

The invention discloses a titanium alloy integral bladed disc and a manufacturing method thereof, which belong to the technical field of titanium alloy material and manufacturing. The integral bladed disc consists of a rotary disc and blades which are integrated, and is characterized in that the rotary disc is made of high-strength titanium alloy and the blades is made of titanium aluminum intermetallic compound. The component transition between the rotary disc and the blades is direct transition. The invention utilizes laser to melt stacked materials layer by layer to directly prepare a near-net-shape titanium alloy integral bladed disc with inflaming retarding and high temperature strength performance without the need of the multi-step hot working process of conventional processing method, remarkably reduces processing amount and improves material utilization rate and structural efficiency; and the rotary disc has high plasticity and strength as well as low-cycle fatigue performance, and the blades have inflaming retarding performance and high temperature strength and rigidity, so as to satisfy the performance requirements of the gas compressor integral bladed disc on the rotarydisc and the blades during the using process.

The invention discloses a life prediction method used for a nickel-base superalloy blade under a thermal mechanical fatigue load. The problems of life prediction and joint representation of low cyclefatigue damage, creep damage and oxidation environment damage of the nickel-base superalloy blade under the TMF load are effectively solved; according to isothermal low cycle fatigue life data of nickel-base alloy under the condition of not causing high-temperature effects of creep, oxidation and the like, fitting is performed to obtain a strain life equation; in combination with a fatigue damagelinear accumulation theory, a fatigue damage model is obtained; a creep damage model is represented as temperature, stress and time functions; the oxidation environment damage is modeled based on an oxidation-cracking mechanism with a continuous oxidation layer at a crack tip; a continuous damage accumulation mechanism is adopted for the three models; and by virtue of stress, strain and temperature data of dangerous position points of the blade, accurate and reliable unified representation of fatigue, creep and oxidation interactive damage, and life prediction of a combined damage model to a nickel-base superalloy member under the thermal mechanical fatigue load is realized.

The invention relates to a titanium alloy integral blade disc with composite performance and a fabricating method thereof. A hub and a spoke of the blade disc are made of titanium alloy, a rim and a blade are made of titanium-base composite materials (or the whole disk is made of titanium alloy, and the blade is made of titanium-base composite materials), and the point of the blade also contains one or more of Cr, V, Mo with higher content so as to have properties of resisting temperature, abrasion and combustion. The hub and the spoke as well as the rim and the blade are sequentially prepared by piling layer by layer through adopting titanium alloy powder, one or more of titanium powder, TiC, B4C, and Cr3C2, and mixture powder of particles of one or more of Cr, V and Mo, which are synchronously conveyed and molten and deposited by adopting laser, so as to obtain the near net-shape titanium alloy integral blade disc with composite performance. The rim and the blade of the blade disc are integer, the hub and the spoke of the disc have high room temperature plasticity and strength as well as low cycle fatigue property, and the rim and the blade have high high-temperature fracture toughness property and high creep resistance.

A rotor assembly for a gas turbine engine, having a rotor member with axially spaced-apart front and rear end portions. A thermal shield is located axially downstream of the rear end portion of the rotor for thermally shielding the same from the hot surrounding environment. The thermal shield includes a rear coverplate and an axial gap between the rear coverplate and the rear end portion of the rotor member.

The invention relates to a device for online monitoring and controlling low cycle fatigue life consumption of components of a steam turbine and a method, belonging to the technical field of the steam turbine. The invention is characterized in that the device consists of a compute server, a database server, a web server, a user browser and a plant supervisory information device; the web server is connected with the user browser, the database server and the compute server respectively; the compute server is connected with the database server which is connected with a digital electric-hydraulic control device of the steam turbine by the plant supervisory information device. The invention has the advantages of being capable of realizing online computing and controlling of transient low cycle fatigue life consumption of a plurality of components of the steam turbine.

The invention relates to a method for predicting the high-low-cycle composite fatigue crack growth life of a turbine joggle structure, and the method comprises the steps: (1), building a crack growth model giving consideration to a crack closure effect; (2), determining a high-cycle load stress intensity factor model; (3), determining a low-cycle load stress intensity factor model; (4), judging whether a current cycle is a high-cycle load or not: executing step (5) if the current cycle is the high-cycle load, or else executing step (6); (5), calculating a composite fatigue lower crack increment, judging whether a next cycle is a low-cycle fatigue load or not: obtaining the maximum crack tip opening displacement of the current cycle if the next cycle is the low-cycle fatigue load, and executing step (7), or else executing step (8); (6), calculating the variance of the low-cycle load lower crack tip opening displacement; (7), calculating the residual crack tip opening displacement and crack increment according to the results inputted at steps (5) and (6); (8), updating the crack length, repeatedly carrying out the steps (4)-(7) if the maximum stress intensity factor is less than the fracture toughness, or else completing the calculation, and obtaining the crack growth life.

A method to estimate the fatigue life of a component operable under cyclic stress is provided. A system including testing means for performing a strain controlled test of a component or a representative specimen of the component, to obtain therefrom a first set of data samples including measured stress amplitude values for varying applied strain levels, and a second set of data samples including measured number of cycles to crack initiation for varying applied strain levels is also provided. The system further includes a modeling means for fitting a first low cycle fatigue material curve on the first set of data samples and a second low cycle fatigue material curve on the second set of data samples.

There is provided a method for fabricating a dual alloy structure that may in turn be machined to fabricate a rotary component for use in a gas turbine engine. The method provides a powder metal (PM) nickel based superalloy and a nickel aluminide intermetallic based alloy. The powder metal (PM) nickel based superalloy displays characteristics, such as improved strength, low cycle fatigue resistance, fracture toughness, and crack growth resistance. The nickel aluminide intermetallic based alloy displays characteristics, such as high temperature creep and oxidation resistance, suitable for use in the outer radial area of an impeller. A bore sub-element is fabricated from the powder metal (PM) nickel based superalloy. A body sub-element is fabricated from the nickel aluminide intermetallic based alloy. The bore sub-element and body sub-element are joined by inertia welding or diffusion bonding at a common mating surface.

Embodiments of the present disclosure relate to nickel-base alloys and methods of direct aging nickel-base alloys. More specifically, certain embodiments of the present disclosure relate to methods of direct aging 718Plus< TM > nickel-base alloy to impart improved mechanical properties, such as, but not limited to, tensile strength, yield strength, low cycle fatigue, fatigue crack growth, and creep and rupture life to the alloys. Other embodiments of the present disclosure relate to direct aged 718Plus< TM >nickel-base alloy, and articles of manufacture made therefrom, having improved mechanical properties, such as, but not limited to, tensile strength, yield strength, low cycle fatigue, fatigue crack growth, and creep and rupture life.

The invention discloses a rhenium-free low-density high-performance nickel-based monocrystalline high-temperature alloy and a heat treatment technology thereof, and belongs to the field of nickel-based monocrystalline high-temperature alloys. The alloy comprises 6.0-8.0wt% of Cr, 8.0-10.0wt% of Co, 6.0-9.0wt% of W, 1.0-3.0wt% of Mo, 0-2wt% of Nb, 3.0-6.0wt% of Al, 1.0-3.0wt% of Ti, 1.0-5.0wt% of Ta, 0.02-0.06wt% of C, 0.001-0.003wt% of B, 0-0.02wt% of Ce, 0-0.01wt% of Y and the balance Ni. The alloy has excellent low-temperature, middle-temperature and high-temperature strength and antioxidation performances, has lasting and low-cycle fatigue behavior the same to that of a second monocrystalline high temperature alloy CMSX-4 with Re content of 3wt%, does not contain a noble element Re, reduces an alloy cost by 70% or more and reduces alloy density by about 3%.

The invention discloses a characterization method of material fatigue, creep, and fatigue-creep interaction service life, and belongs to the field of service life prediction of aero-engine critical materials. The characterization method is used for solving service life characterization and prediction problems of materials under low cycle fatigue, creep, and fatigue-creep interaction conditions. According to the principles, a power function form service life prediction method non-linear behavior characterization capacity is established via fatigue-creep interaction, low cycle fatigue, and creeptests of materials at different holding time, and obtaining of effective holding time and normalization dimensionless service life via normalization calculation method. The characterization method iscapable of realizing accurate characterization of service life of materials under low cycle fatigue and fatigue-creep interaction conditions, and especially, consideration and accurate prediction ofcreep service life can be realized. The advantages of the characterization method are that consideration of both physical mechanisms and model implementation convenience is realized, and material lowcycle fatigue, creep, and fatigue-creep interaction service life characterization and prediction problems are solved effectively.

The invention relates to an online calculation-control method on the equivalent stress of the high-middle-pressure rotor of turbine, wherein if said factor is over preset value, it can online control the temperature change rate of main steam, and the load change rate to improve equivalent stress and prolong the service life. If the factor reaches the alarm value, it will alarm, and stop in preset time to control the equivalent stress and prolong the service life.

A rotating machine, has a rotary component, which includes a memory device for storing data relating to the past use of the component. The data are associated with rotational speed and ambient temperature, which are detected by detectors either on or off the rotary component. The stored data may be the raw temperature and speed data as sampled over time, which are then used to derive values of low-cycle fatigue and creep damage. These fatigue and creep values are, in turn, correlated with the load profiles of the component to arrive at a value of elapsed lifespan for the component. Alternatively, the stored data may be the fatigue and creep values and/or, preferably, values of elapsed and remaining lifespan of the component. In a second embodiment the detectors are located on the machine casing along with an evaluation unit.