Method for measuring compact tension specimen fracture parameters by using double extensometers

A compact tensile specimen and extensometer technology, applied in measuring devices, instruments, scientific instruments, etc., can solve the problems of unpublished patents, inability to provide design curves, difficult calculations, etc., and achieve critical CTOD values ​​with high precision , The test method is simple and easy to implement, and the data processing is simple.

Active Publication Date: 2012-07-11
725TH RES INST OF CHINA SHIPBUILDING INDAL CORP
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Problems solved by technology

The EPRI design curve has high precision and is suitable for compact tensile tests, but the calculation is difficult, and the influence of the actual plate thickness is not considered, so the design curve under the actual plate thickness cannot be given
[0017

Method used

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  • Method for measuring compact tension specimen fracture parameters by using double extensometers
  • Method for measuring compact tension specimen fracture parameters by using double extensometers
  • Method for measuring compact tension specimen fracture parameters by using double extensometers

Examples

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Embodiment 1

[0049] The fracture parameters of the hull structural steel A36 steel plate were tested by the double extensometer method. The size of the compact tensile specimen was 20mm×50mm×48mm, and the length of the prefabricated fatigue crack was 27.86mm. Two extensometers were respectively clamped on the surface of the specimen and the 25 mm from the sample surface. The mechanical properties of the steel plate are as follows: yield strength 380MPa, tensile strength 530MPa, reduction of area 74.5%, elongation after fracture 33%, elastic modulus 217GPa.

[0050] Two extensometers simultaneously record the opening displacement V of the two test points 1 , V 2 , stop when loaded to the maximum load, the measured load-displacement curve is as follows image 3 shown. Two extensometers respectively measure the opening displacement V corresponding to the maximum load point 1 , V 2 2.23mm and 3.72mm respectively. Put the test value into the formula (1) to calculate the critical CTOD valu...

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Abstract

The invention discloses a novel method for measuring compact tension specimen fracture parameters by using double extensometers. The novel method comprises the following steps of: measuring two opening displacements by using the double extensometers; obtaining a crack tip opening displacement (CTOD) of a compact tension test through calculation by using a triangular relation; and calculating a CTOD value under each load and a nominal stress corresponding to the CTOD value, and obtaining a relation between the nominal stress and the CTOD, thereby obtaining a CTOD design curve of the compact tension test. The fracture parameter test method disclosed by the invention has the characteristics of simpleness, easy operation, simpleness for processing data, high precision of a critical CTOD value, comprehensive data, large information quantity, freeness from test precision influences of other parameters, such as strength, Young modulus, rotary factor and load, capabilities of obtaining the CTOD data of the whole test loading process and obtaining the CTOD design curve of the compact tension test under an actual board thickness condition.

Description

technical field [0001] The invention relates to the technical field of metal material fracture toughness testing, in particular to a method for measuring the fracture parameters of a compact tensile sample by using a double extensometer. Background technique [0002] Crack tip opening displacement (hereinafter referred to as "CTOD", denoted as "δ") and CTOD design curve are important parameters in elastic-plastic fracture mechanics, which are widely used in the safety and reliability evaluation of metal components. [0003] At present, the measurement methods for the critical CTOD value of compact tensile specimens mainly include: flexibility method, section method, and microscope direct measurement method. The flexibility method has a short test period and has been widely used in actual operation, but its test accuracy is low; the section method and direct microscope measurement method have high precision, but due to the long test period due to the complicated preparation o...

Claims

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Application Information

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IPC IPC(8): G01N3/00
Inventor 薛钢杨光王任甫
Owner 725TH RES INST OF CHINA SHIPBUILDING INDAL CORP
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