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Damage calculation method for low-cycle fatigue and high-strength impact coupling based on local stress strain method

A technology of local stress and low cycle fatigue, which is applied in the direction of applying repeated force/pulsation force to test the strength of materials, and can solve the problems of inapplicable low cycle fatigue and high-strength impact

Inactive Publication Date: 2013-10-09
BEIHANG UNIV
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Problems solved by technology

Nominal stress method was previously used to analyze high cycle fatigue and low strength, but not for low cycle fatigue and high strength impact

Method used

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  • Damage calculation method for low-cycle fatigue and high-strength impact coupling based on local stress strain method
  • Damage calculation method for low-cycle fatigue and high-strength impact coupling based on local stress strain method
  • Damage calculation method for low-cycle fatigue and high-strength impact coupling based on local stress strain method

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Embodiment Construction

[0143] The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

[0144] The following examples are as follows figure 1 The process shown is implemented, and the case selects an actuator joint as the fatigue-shock analysis object, which mainly includes the conversion of local stress and strain, the calculation of fatigue life before and after impact, the calculation of fracture toughness under fatigue damage, and the comprehensive reliability of establishment.

[0145] The invention provides a damage calculation based on local stress-strain low-cycle fatigue and high-strength impact coupling. The specific steps of the method are as follows:

[0146] Step 1: Analyze the fatigue load spectrum, and calculate the nominal stress-strain (S 1 ,e 1 ),(S 2 ,e 2 ),...,(S m ,e m ), and converted into local stress-strain (σ 1 ,ε 1 ),...,(σ m ,ε m ).

[0147] The fatigue cyclic unit load spectrum of an actuat...

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Abstract

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.

Description

technical field [0001] The invention provides a low-cycle fatigue and high-strength impact coupling damage calculation method based on a local stress-strain method, which belongs to the technical field of life modeling and reliability evaluation. Background technique [0002] Products with a fatigue failure mechanism are threatened by impact loads in addition to complex fatigue loads. Both impact load and fatigue load are dynamic loads, which will cause cracks in the product from the perspective of macroscopic damage, and finally the cracks will be unstable and fracture. However, the loading rate of impact load is much larger than that of general fatigue load, and the Properties tend to change, and the corresponding damage characteristics are also quite different from low loading rates, so impact damage and fatigue damage have similarities and differences. [0003] Each fatigue load will lead to fatigue damage, and when the damage accumulates to a certain value, the product...

Claims

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Application Information

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IPC IPC(8): G01N3/32
Inventor 陈云霞陈红霞康锐
Owner BEIHANG UNIV
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