Method and system for testing three-dimensional stress of residual stress of material by utilizing nanoindentation method

Abstract

The invention discloses a method and a system for testing three-dimensional stress of residual stress of a material by utilizing a nanoindentation method, and relates to the technical field of residual stress testing, and the method comprises the following steps: carrying out nanoindentation testing on a to-be-detected sample to obtain a relationship between a load and a press-in depth; obtainingthe hardness of the to-be-detected sample material and the indentation projection area of the to-be-detected sample according to the relationship between the load and the press-in depth; calculating athree-dimensional stress proportion by adopting a finite element analysis method according to the isomerism of the to-be-detected sample material; and according to the three-dimensional stress proportion, the hardness of the to-be-detected sample material and the indentation projection area of the to-be-detected sample, obtaining three-dimensional stress in an unstressed state and three-dimensional stress in a tensile stress state. The method and the system provided by the invention can realize the detection of the three-way residual stress of a test micro area.

Description

technical field [0001] The invention relates to the technical field of residual stress testing, in particular to a method and a system for testing the three-dimensional stress of material residual stress by using a nano-indentation method. Background technique [0002] In high-energy industries such as petrochemicals, nuclear energy, and aerospace, mechanical equipment is developing towards more efficient heat treatment systems. For high-end equipment such as high-temperature gas-cooled reactors, new-generation aeroengines, and gas turbines, enhancing the high-efficiency and compactness of the heat exchange system is the key to improving efficiency. In recent years, the plate-fin heat exchanger (PFHE) with plate-fin structure as the basic cooling unit has been widely developed and applied. However, the compactness and high efficiency of PFHE restrict its safety and reliability to a certain extent. There are a large number of brazed joints in the plate-fin heat exchanger. D...

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Problems solved by technology

[0003] For the residual stress test of brazed joints, due to the small size of the weld and the diffusion zone, conventional testing methods such as neutron diffraction and X-ray methods are difficult to directly test

The nano-indentation method for testing residual stress has been widely studied, but the theory of residual stress testing by this method is only applicable to bidirectional stress, that is, the test of plane stress state, and it is not applicable to the three-dimensional stress state of structures such as brazed joints. It is difficult to test directly, so there is an urgent need for a method that can test the three-dimensional residual stress in a small area

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