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A Method of On-line Measuring Fatigue Crack Propagation of Plexiglass

A fatigue crack propagation, plexiglass technology, used in measuring devices, using repetitive force/pulse force to test the strength of materials, instruments, etc., can solve the problems of inaccurate measurement results, complicated measurement procedures, inconvenient data processing, etc. Reliable results, simple data processing, and improved measurement accuracy

Inactive Publication Date: 2018-08-28
TSINGHUA UNIV
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Problems solved by technology

[0004] The purpose of the present invention is to provide a method for online measurement of organic glass fatigue crack growth, so that it can more conveniently measure the quantitative relationship between crack growth rate and stress intensity factor range, and overcome the need to stop the machine for measurement in existing traditional methods The defects caused by the complex measurement process, inconvenient data processing and inaccurate measurement results, so as to realize the real-time and effective measurement of the fatigue crack growth of plexiglass

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  • A Method of On-line Measuring Fatigue Crack Propagation of Plexiglass
  • A Method of On-line Measuring Fatigue Crack Propagation of Plexiglass
  • A Method of On-line Measuring Fatigue Crack Propagation of Plexiglass

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Embodiment Construction

[0027] The method of the present invention utilizes a transmission type caustics optical testing system to obtain the caustic speckle image near the crack tip and the crack propagation process of the plexiglass fatigue crack propagation process, and through real-time image processing of the caustic speckle image in the computer buffer area, Online accurate calculation of crack length and crack tip stress intensity factor. Based on the real-time processing of a large amount of test data, conditions are selected for the caustic speckle images in the computer cache area, the number of focal speckle images stored in the near-threshold region expansion stage and the stable expansion stage is controlled, and the storage capacity of the fast tending to fracture toughness stage is improved. The number of focal spot images is increased, thereby improving the measurement accuracy of the plexiglass fatigue crack growth test, while reducing the amount of image storage and data analysis and...

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Abstract

The invention provides a method for performing online measurement on fatigue crack propagation of organic glass and belongs to the fields of fatigue fracture mechanics test technologies and digital image technologies. According to the method, a transmission-type caustic optical technology is adopted, a CCD camera is utilized to online and continuously collect propagation processes of shadow spot images and cracks nearby crack tips of an organic glass testpiece containing cracks under different fatigue circle periods, image processing and condition selection are performed on shadow spot images in a cache region of a computer in real time, and the crack length and the crack tip stress strength factor are calculated. A caustic optical testing technology adopted in the method refers to non-contact real-time measurement, is high in intuition, simple in geometrical optics model, easy in stress strength factor calculation, convenient in data processing and accurate and reliable in test result; compared with a traditional fatigue crack propagation measurement method, the method provided by he invention is capable of omitting tedious processes of manually measuring the crack length and solving out the stress strength fact range, and avoiding the influence of crack length halt measurement on the test result.

Description

technical field [0001] The invention relates to an on-line method for measuring fatigue crack growth of plexiglass, and belongs to the fields of fatigue fracture mechanics testing technology and digital image technology. Background technique [0002] The fatigue crack growth rate is an important index to reflect the fatigue fracture resistance of cracked components, and it is also an essential parameter for estimating the fatigue crack growth life of components. There is a relationship between the crack growth rate and the range of the stress intensity factor at the crack tip. A large number of fatigue crack growth tests show that the fatigue crack growth rate and the range of the stress intensity factor have the characteristics of three stages in the logarithmic coordinate system, that is, the lower stress intensity The near-threshold region expansion stage in the range of stress intensity factors, the stable expansion stage in the intermediate stress intensity factor range...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N3/32
CPCG01N3/32G01N2203/0066G01N2203/0641
Inventor 姚学锋刘伟王申马寅佶郝文峰原亚南
Owner TSINGHUA UNIV
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