Low-cycle creep and fatigue life evaluation method under conditions of high temperature and multiaxial spectrum load

Abstract

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.

Description

technical field

[0001] The invention relates to the field of fatigue strength, in particular to a multiaxial block load low-cycle creep-fatigue life evaluation method under high temperature conditions. Background technique

[0002] High-temperature creep fatigue strength design is an important part of the strength design of high-temperature components such as aero-engines and gas turbines. The load forms of parts and equipment in actual service are complex and diverse, and it is impossible to completely reproduce the actual service load history in the design stage, and the use of load spectrum blocks to simulate the load of parts has become an indispensable method for part fatigue strength design. , Creep fatigue is an important factor restricting high-temperature components such as aero-engines and gas turbines. Therefore, low-cycle multiaxial creep-fatigue damage estimation and life prediction under block loading have been widely used in the design of these high-temperatur...

Examples

Embodiment Construction

[0046] The specific embodiments of the present invention will be described with reference to the accompanying drawings and calculation examples.

[0047] The damage estimation to be performed in the present invention includes multiaxial fatigue damage estimation and creep damage estimation. According to the damage calculation result, N is the number of load history described by the block load that the part can withstand, which is the predicted fatigue life.

[0048] Step 1): Read the stress-strain history in the load block, and use the Mises criterion to find the equivalent strain ε of each point eq , disconnect the load spectrum from the maximum equivalent strain, and move the load history data before this point to the end of the load history to complete the load arrangement;

[0049] Suppose the fast load history is as follows:

[0050] Table 1 Load History Data

[0051]

[0052] According to the load history, the equivalent strain of each point can be obtained, and the...

technical field

[0001] The invention relates to the field of fatigue strength, in particular to a multiaxial block load low-cycle creep-fatigue life evaluation method under high temperature conditions. Background technique

[0002] High-temperature creep fatigue strength design is an important part of the strength design of high-temperature components such as aero-engines and gas turbines. The load forms of parts and equipment in actual service are complex and diverse, and it is impossible to completely reproduce the actual service load history in the design stage, and the use of load spectrum blocks to simulate the load of parts has become an indispensable method for part fatigue strength design. , Creep fatigue is an important factor restricting high-temperature components such as aero-engines and gas turbines. Therefore, low-cycle multiaxial creep-fatigue damage estimation and life prediction under block loading have been widely used in the design of these high-temperatur...

Examples

Embodiment Construction

[0046] The specific embodiments of the present invention will be described with reference to the accompanying drawings and calculation examples.

[0047] The damage estimation to be performed in the present invention includes multiaxial fatigue damage estimation and creep damage estimation. According to the damage calculation result, N is the number of load history described by the block load that the part can withstand, which is the predicted fatigue life.

[0048] Step 1): Read the stress-strain history in the load block, and use the Mises criterion to find the equivalent strain ε of each point eq , disconnect the load spectrum from the maximum equivalent strain, and move the load history data before this point to the end of the load history to complete the load arrangement;

[0049] Suppose the fast load history is as follows:

[0050] Table 1 Load History Data

[0051]

[0052] According to the load history, the equivalent strain of each point can be obtained, and the...

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