The invention relates to a method of measuring an open angle of a crack tip based on in-situ SEM. The method comprises the following steps: test sample preparation: machining a test sample to achievea needed physical dimension and surface coarseness; test sample clamping and scanning electron microscope imaging: clamping the test sample on a test sample table of an in-situ tester till the surfaceof the test sample can be observed clearly; test condition setting for starting of the test: setting the loading parameter of the in-situ tester and pre-fabricating a crack by adopting a pull-pull fatigue load; fracture test and image acquisition: calculating a CTOA value and measuring the length a of the crack: acquiring the evolutionary trend of CTAOA-delta a: drawing the calculated CTOA and acrack growth increment delta a measured by the scanning electron microscope in a same coordinate system to obtain a tendency chart of CTOA-delta a. The method achieves non-contact measurement of CTOAwithout special treatment on the surface of the test sample. In the process, no complicated test operation steps are available, the post-treatment is convenient and the precision is relatively high.

Method of measuring open angle of crack tip based on in-situ SEM

The invention discloses a method for estimating plane-strain fracture toughness of a metal material, and belongs to the technical field of fracture toughness of metal materials. The method comprises three steps: performing a fracture toughness experiment on a small sample to obtain an experimental value Kq, performing linear fitting on Kq2B and specimen thickness B and performing accurate calculation through straight line slope to obtain KIC. According to the method, the plane-strain fracture toughness of the material can be measured simply and effectively, so that the experiment cost is greatly reduced; in addition, as the KIC of materials (such as amorphous alloys or nano-metal materials) cannot be measured due to a preparation process or relatively high toughness of the materials, accurate parameters can be provided through the method, so that a strong basis is provided for material selection, and particularly, a theoretical basis is provided for the damage tolerance design of a component of the aviation manufacturing industry.

Method for estimating plane-strain fracture toughness of metal material

The invention relates to a composite material I-type layering bridging law determination method based on a virtual layering expanded test The method comprises the following steps of 1, conducting an I-type layering test to measure a layering expanding R curve; 2, establishing an I-type layering test piece limited element model, and adopting a dual-linear cohesion unit to simulate a layering interface; 3, embedding the R curve into the limited element model to conduct I-type layering simulation; 4, calling out a set of one to one corresponding data of load P, a displacement d, a layering length a and a stretching displacement delta* at a layering starting position from a numerical value simulation result, and calculating a fracture toughness GIC(a), wherein the data; 5,using the data of the GIC(a) and delta*, determining sigmag(delta*) of generalized crack surface bridging stress with the change of delta*, and conducting fitting to obtain a bridging law specific form The composite material I-type layering bridging law determination method based on the virtual layering expanded test is applicable to determination of a composite material I-type layering bridging law, has obvious advantages compared with a pure test testing means, can conveniently achieve correspondence between the stretching displacement and fracture toughness data, simplify the test operation, and lower the test testing error

Composite material I-type layering bridging law determination method based on virtual layering expanded test

The invention provides a method and an apparatus for testing fracture toughness of pipeline steel in a hydrogen-containing synthetic natural gas environment. The testing method comprises the followingsteps: initial cracks are prefabricated in air; under a condition environment, a stretching test is carried out, in order to obtain a test crack expansion amount; a curve of J-integration-test crackpropagation amount is drafted, in order to complete test of the fracture toughness of pipeline steel in the hydrogen-containing synthetic natural gas environment. The invention also provides the testing apparatus of the testing method. The testing apparatus and the testing method can be used for practically reflecting practical service performance of the pipeline steel, and the apparatus and the method have the advantages of simple and easy operation, accurate result, and reliability.

Method and apparatus for testing fracture toughness of pipeline steel in hydrogen-containing synthetic natural gas environment

The invention relates to the technical field of crack length measurement in fracture mechanics tests, and provides a method for measuring the crack length of a three-point bending standard sample. Themethod comprises the steps of providing a measurement equation for determining the crack length, a layout mode of a resistance strain gauge and a method for determining a crack length. The measurement equation can be obtained by adopting a prefabricated notch sample. The layout mode of the resistance strain gauge includes an arrangement direction and an arrangement position; and the method for determining the crack length includes a force value measurement processing mode, a strain measurement processing mode and measurement data processing mode. The measurement method capable of determiningthe crack length of the three-point bending standard sample is provided. The measurement method is simple, practical and reliable, has high measurement efficiency and facilitates automatic acquisitionand monitoring.

Method for measuring crack length of three-point bending standard sample based on strain measurement technology

The invention provides a method for testing the microzone fracture toughness of a material. The method comprises the following steps: preparing an ultrathin single-edge notched tensile (SENT) specimen; performing repeated loading and unloading operations on an in-situ tensile test machine; recording test load Fi, crack length ai and notch opening displacement Vi by virtue of a scanning electron microscope in-situ test machine; calculating a Ki value for a brittle material and calculating a Ji value for a ductile material; and drawing a K-a curve or J-R curve capable of characterizing crack propagation fracture resistance, thereby obtaining a stress intensity factor K or J integral capable of characterizing the fracture toughness of a miniature specimen. The ultrathin SENT specimen is adopted to measure the microzone fracture toughness of a metallic material, so that the problem that measurement on fracture toughness of ultrathin members and accurate microzones of a large specimen based on traditional standards cannot be realized is solved, and the method has the characteristics of accurate crack tip positioning and high dimension measurement accuracy.

Method for testing microzone fracture toughness of material

The invention puts forward an annealing system and method for welded rotors. The annealing system comprises multiple heating devices and multiple temperature measuring devices; the multiple heating devices are arranged on multiple heating zones of the welded rotors; the multiple temperature measuring devices are arranged on the multiple heating zones of the welded rotors and are connected with themultiple heating devices; and the annealing temperatures of the multiple heating zones are different. By the aid of the annealing system for the welded rotors, manual operations can be reduced, and the heating quality is stable.

Annealing system and method for welded rotors

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Method for testing microzone fracture toughness of material

Annealing system and method for welded rotors