A Method of Obtaining Material Strain-Life Curve by Small Punch Fatigue Test

Abstract

The invention discloses a method for obtaining a material strain-life curve through a small punch fatigue test, which relates to the technical field of material fatigue performance testing, and specifically includes: obtaining the maximum load-fatigue life curve of a material; obtaining material mixed hardening model parameters; establishing a small The finite element model of the punch fatigue test; determine the critical surface of the small punch fatigue sample and obtain the stress-strain history on the critical surface; determine the material energy-life formula; determine the material strain-life curve of uniaxial fatigue. The beneficial effect of the present invention is that the strain-life curve of the material is obtained through the small punch fatigue test, the single uniaxial fatigue test and the finite element analysis; then the fatigue performance of the material can be accurately tested, and the in-service equipment material, local micro-area can be evaluated The fatigue performance of materials and new materials can also save a lot of materials, which is of great significance to the fatigue performance testing of in-service equipment materials, new materials and local micro-regions.

Description

Technical field [0001] The present invention relates to the field of material fatigue performance testing techniques, in particular to a method of obtaining a material strain - life curve for a small punch fatigue test. Background [0002] Many equipment or mechanical components used in petrochemical, electric power, aerospace and other fields have long been in service under high temperature, high pressure, corrosion and fatigue conditions, and the problem of mechanical properties degradation of materials inevitably occurs. With the accumulation of service time, these equipment or mechanical parts are facing serious problems such as overdue service and replacement: on the one hand, it is necessary to evaluate the mechanical properties of these equipment or mechanical components to prove whether they have the ability to extend life; on the other hand, due to the needs of economic development, the devices in various industries are developing in the direction of compact, ultra-large...

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Problems solved by technology

However, there are very few researches on the small punch fatigue test at home and abroad. The existing research only proves that the material in the small punch fatigue test belongs to fatigue failure, but does not prove whether the fatigue performance of the material obtained by the small punch fatigue test is reliable, that is, Uniaxial fatigue test results for materials not available from small punch fatigue tests

The existing problems are mainly: the relationship between the small punch fatigue test results and the uniaxial fatigue test results is not clear, and the uniaxial fatigue test results of the material cannot be obtained through the small punch fatigue test

Due to the complex stress state of the small punch fatigue specimen, which belongs to the category of multiaxial fatigue, it is very difficult to correlate the test results of small punch fatigue and uniaxial fatigue

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