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Evaluation method of blunt notch fatigue strength loss coefficient of titanium alloy based on cycle life

A technology of cycle life and fatigue strength, applied in the direction of strength characteristics, the use of repetitive force/pulsation force to test the strength of materials, instruments, etc., can solve the problem of inapplicable fatigue strength loss coefficient and so on

Active Publication Date: 2020-07-07
FOSHAN UNIVERSITY
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  • Application Information

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Problems solved by technology

None of the current evaluation methods are suitable for the evaluation of high-cycle and ultra-high-cycle fatigue strength loss coefficients

Method used

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  • Evaluation method of blunt notch fatigue strength loss coefficient of titanium alloy based on cycle life
  • Evaluation method of blunt notch fatigue strength loss coefficient of titanium alloy based on cycle life
  • Evaluation method of blunt notch fatigue strength loss coefficient of titanium alloy based on cycle life

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Embodiment 1

[0020] Taking TA15 titanium alloy as an example, the specific steps of blunt notch fatigue strength evaluation are as follows:

[0021] (1) Take the smooth TA15 titanium alloy specimen and mark it as specimen 1, conduct ultra-high cycle fatigue test on specimen 1 by ultrasonic fatigue method, test frequency 20kHz, obtain the fatigue strength-life data of specimen 1, and draw the specimen 1's fatigue Se-Ne curve, and mark this curve as fatigue life curve 1, according to fatigue life curve 1, it is obtained that specimen 1 is at 10 9 Fatigue strength σ of fatigue strength at cycles e = Fatigue limit value S of 424MPa specimen 1 e ;

[0022] (2) The σ of specimen 1 obtained in step (1) e =424MPa into the formula The intrinsic dimension a of the titanium alloy is obtained m =0.044mm, where σ e For specimen 1 in 10 9 Fatigue strength at cycles, Y is shape factor, Y=1.12, △K th It is the threshold value of fatigue crack growth and its value is 5.6MPa·m 1 / 2 ;

[0023] (3) ...

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Abstract

The invention discloses a titanium alloy obtuse notch fatigue strength loss coefficient evaluation method based on a cycle life. The method comprises the following steps: on the basis of super high-cycle fatigue testing results and a mathematic model, establishing obtuse material notch criterions, introducing cycle life factors, and establishing a set of obtuse notch fatigue strength evaluation models based on a cycle life; rapidly judging whether a notch is an obtuse notch or not rapidly by using the models, and estimating root sizes of different notches, different theoretic stress concentration factors kt and different cycle lives. According to the method, the phenomenon that fatigue strength of a notch is simply evaluated according to the root size of the notch is avoided.

Description

technical field [0001] The invention belongs to the field of nonferrous metal manufacturing and relates to a method for evaluating the fatigue notch strength of titanium alloys based on cycle life. Background technique [0002] Titanium alloys have the advantages of light weight, high strength, corrosion resistance, and moldability, and are widely used in aerospace, steam turbines and other fields. However, titanium alloys have significant notch sensitivity, and titanium alloys inevitably have processing gaps or structural gaps in the engineering manufacturing process. There are stress concentration in these notches, and the fatigue failure crack initiation position. The notches of structural parts can be divided into: sharp notches and blunt notches. Sharp notches can usually be treated as cracks, while the fatigue strength of blunt notches is affected by the size of the notch root and the theoretical stress concentration factor Kt. The evaluation of its fatigue strength ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N3/32G01N3/06G01N29/04
CPCG01N3/06G01N3/32G01N29/04G01N2203/0073G01N2203/0658
Inventor 聂宝华陈东初蒙宇吕锦源赵子华张峥孙海波刘抒
Owner FOSHAN UNIVERSITY