Test method for crack growth rate of linear gradient material

Abstract

The invention discloses a test method for a crack growth rate of a linear gradient material. The test method comprises the following steps: applying alternating load to a compact tension specimen through a fatigue test machine; rewriting a function relationship of parameters at a test control end; introducing a gradient correcting item for measuring crack length and a gradient correcting item for calculating load; and accurately controlling a test progress and automatically correcting, thereby acquiring test data and acquiring the crack growth rate of the gradient material. The test method provided by the invention has the advantages that the test method is fit for testing the crack growth rate of the linear gradient material, no human intervention is required in the testing period, the test is automatically performed and the precision is high.

Description

technical field [0001] The invention relates to a fatigue crack growth rate test method, in particular to an automatic test method for the crack growth rate of a linear gradient material test piece, belonging to the technical field of material performance detection. Background technique [0002] Fatigue failure under cyclic loading is the main failure mode of engineering structures, and the fatigue growth performance of materials is an important parameter for structural damage tolerance design. Crack growth rate testing of materials can determine the maintenance and service life of structures and their components cycle to ensure the safety and reliability of the structure during service. [0003] Linear gradient materials have been widely used in engineering in recent years because of their smoothest performance transition, easy processing, and excellent functional and structural integration design of gradient materials. Prerequisites for tolerance design and analysis. How...

AI Technical Summary

Problems solved by technology

Among them, the results obtained by the visual inspection method cannot be automatically fed back to the test system, and manual intervention is required. At the same time, the measurement process is greatly affected by human factors; the potential method has high requirements on the material of the test piece and is not widely used; And the crack length measurement method with high precision, this method converts the crack length into the crack opening displacement which can be directly obtained by the test system, so that the experimental test can be carried out automatically, the conversion relationship between the crack length and the opening displacement depends on the specimen itself Stiffness, while the distribution of material stiffness in gradient materials changes, the conversion formula for uniform materials given in the standard is no longer applicable

[0005] (2) There is an error in the test load control

However, affected by the stiffness of the material change, the stress distribution at the crack tip is different from that of a uniform material. Directly using the load on the uniform material load and the stress intensity factor function relationship given in the standard will cause a large error

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