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A Method for Measuring Stress Concentration at the Weld Toe of Thick Plate Butt Joint

A technology of butt joint and stress concentration, which is applied in electromagnetic measurement devices, measurement of electric/magnetic solid deformation, and the use of applied stable tension/pressure to test the strength of materials, etc., to achieve the effect of reducing errors, low cost, and intuitive results.

Inactive Publication Date: 2017-06-13
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of this invention is to solve the problems existing in the calculation of the stress concentration factor of the welding toe by the above method, and propose a method of directly measuring the stress concentration factor of the welding toe by using the parallel patch of the resistance strain gauge

Method used

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  • A Method for Measuring Stress Concentration at the Weld Toe of Thick Plate Butt Joint
  • A Method for Measuring Stress Concentration at the Weld Toe of Thick Plate Butt Joint
  • A Method for Measuring Stress Concentration at the Weld Toe of Thick Plate Butt Joint

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specific Embodiment approach 1

[0028] Specific Embodiment 1: A method for measuring the stress concentration at the weld toe of a thick plate butt joint in this embodiment is carried out according to the following steps:

[0029] 1. First, take a standard tensile sample from the butt joint of thick plates, polish the side of the tensile sample, and wipe with acetone to remove oil stains;

[0030] 2. Paste the strain gauge evenly on one side of the tensile sample treated in step 1 to ensure that the axis of the strain gauge is consistent with the stretching direction, the transverse connection line of the strain gauge is located at the undercut of the weld toe, and the distance between each strain gauge greater than 2mm;

[0031] 3. Connect the strain gauge to the strain gauge, stretch the sample through a universal tensile machine at room temperature, and control the tensile force so that complete elastic deformation occurs everywhere in the sample;

[0032] 4. Under the premise that the tensile force rema...

specific Embodiment approach 2

[0034] Embodiment 2: This embodiment differs from Embodiment 1 in that: in step 3, the tensile load of the universal tensile machine is 5% to 10% of the tensile strength of the sample. Others are the same as in the first embodiment.

specific Embodiment approach 3

[0035] Specific embodiment 3: The difference between this embodiment and specific embodiment 1 is that in step 5, the strain value at the weld toe in step 4 is compared with the average strain value, which is carried out by using the following formula: Among them, σ max is the maximum stress value, σ av is the mean stress value. Others are the same as in the first embodiment.

[0036] The content of the present invention is not limited to the content of the above-mentioned embodiments, and a combination of one or several specific embodiments can also achieve the purpose of the invention.

[0037] Verify the beneficial effects of the present invention through the following examples:

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Abstract

A method for measuring stress concentration at the weld toe of a thick plate butt joint, which relates to a method for measuring stress concentration at the weld toe. The present invention aims to solve the problems existing in calculating the stress concentration factor of the weld toe by the above method. The method of the present invention is as follows: firstly, the test is polished and cleaned, and then the strain gauge is pasted, the strain gauge is connected to the strain gauge, stretched, extrapolated and fitted by a parabolic interpolation method, and the strain value at the weld toe is measured; Then attach the substrate, measure the average strain value of the sample, and complete after comparing the two. Compared with the traditional three-strain gauge method, the method of the present invention is especially suitable for various irregular weld toe shapes without assumptions, and the patch method is simple, and it is simpler and easier to operate when measuring the stress concentration at the weld toe of a thick plate, and The result is more intuitive and accurate.

Description

technical field [0001] The invention relates to a method for measuring stress concentration at a weld toe. Background technique [0002] In a welded structure, no matter what welding method is used, there will be a change in cross-section at the back weld toe. The stress concentration at the weld toe due to the sudden change in section and the loss of uniformity in the structural shape is an important reason for the fracture and fatigue damage of the welded structure, and fatigue cracks often initiate at the weld toe. For thick plates, the damage is often caused by fatigue failure. Therefore, accurate measurement of the stress concentration at the weld toe of the thick plate has important practical significance for the prediction of component life. [0003] Usually the stress concentration factor (K T ) represents the so-called stress concentration degree, which is the maximum stress value (σ max ) and mean stress value (σ av ), the ratio of where, is the maximum stre...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N3/08G01B7/16
Inventor 杨雨禾雷正龙刘鸣
Owner HARBIN INST OF TECH