A crack estimation device which accurately estimates a crack inside a structure is provided. The crack estimation device includes: a measurement unit which measures deformation of a measurement plane as a measurement plane deformation vector; a model generation unit which sets deformation of the measurement plane when a crack is generated in a crack generation plane, as a measurement plane estimated change vector for multiple types of crack candidates; and a crack state analysis unit which obtains a similarity between the measurement plane deformation vector and the measurement plane estimated change vector, normalizes the similarity, and estimates the crack generated in the crack generation plane from a result obtained by multiplying a vector of a state quantity indicating a state of the crack generation plane by the normalized similarity for each crack candidate, and adding together results of the multiplication for all the crack candidates.

Disclosed is an anti-buckling jig of a fracture toughness test. The anti-buckling jig includes: a first jig unit provided in a form of surrounding one side surface of a specimen; a second jig unit provided in a form of surrounding the other side surface of the specimen; and a screw provided to allow the first jig unit and the second jig unit to be coupled to each other. During the fracture toughness test of the specimen, the first jig unit and the second jig unit simultaneously support both sides of the specimen, so that the specimen is cracked in a single direction.

A rock mass shear test system for high-energy accelerator computed tomography (CT) scanning includes double horizontal loading devices, a first bearing device for bearing a static shear box, a second bearing device for bearing a dynamic shear box, and a normal loading device, etc. In the test, the double horizontal loading devices simultaneously apply an identical loading force to the rock mass, and the normal loading device applies a shear force to the rock mass. The double horizontal loading devices are provided in parallel and spaced apart, a loading force is applied in the horizontal direction, and a shear force is applied in the vertical direction, so that the loading cylinder and the rock mass sample are effectively prevented from interfering with each other during the accurate scanning process of the shearing progressive failure process of the rock mass.

A plate specimen is extracted from a qualified HIC resistant material having a Heat number. The plate specimen is supported on a female die of a guided bend system and a force is applied with a male die of the guided bend system to a predetermined middle portion of the plate specimen to develop a U-shaped bent portion in the plate specimen. A curved sample is extracted from the predetermined middle portion having the U-shaped bent portion, the curved sample simulates a cold forming ratio of a line pipe having a particular pipe diameter that is to be subsequently manufactured from the qualified Heat number. A standardized HIC test on the extracted curved sample. Respective values of Crack Length Ratio (CLR), Crack Sensitivity Ratio (CSR) and Crack Thickness Ratio (CTR) are calculated for the curved sample subsequent to the standardized HIC test on the curved sample. The qualified Heat number is validated for manufacturing the line pipe having the particular pipe diameter in response to determining that the calculated respective values of CLR, CSR, and CTR not greater than the corresponding predetermined maximum threshold values for the CLR, CSR, and CTR.

A testing system for causing a physical change in a crack tip region of a crack within a specimen. The testing system includes a load application system for applying a load to the specimen having the crack formed therein, an electrothermal system for applying an electrical current through the specimen and comprising a power supply and a controller operably coupled to the load application system and the electrothermal system. The load application system configured to perform a crack growth test on the specimen. A method of thermally influencing a crack tip region of a crack within a specimen includes applying at least one pulse of current to the specimen to generate flux tangentially around the crack within the specimen and at the crack tip region and causing the crack tip region of the crack within the specimen to reach a predetermined activation temperature.

Coal rock three-dimensional strain field visual system and method are provided under a complex geological structure. The system includes a stress condition simulation system and a strain monitoring system. The stress condition simulation system includes a similar simulation experiment rack, a loading system and a circular slideway. The method includes preparing a 3D printing wire, printing a strain visual similar model, simulating a stratum dip angle and a gas-containing condition, applying stress fields, recording a cracking and dyeing condition of microcapsules inside the model, and the like. The system can realize tracing the generation and development of internal cracks in simulation models with complex geological conditions, and tracing the three-dimensional movement of internal ink dots to draw four-dimensional images of displacement fields.

A discontinuous deformation measurement method based on infrared and visible light cameras may include: preparing a conductive film and a random speckle pattern on a surface of the conductive film; obtaining a visible image and an infrared image under a loading stage; applying a crack boundary detection to the visible image to obtain an initial coordinate of a micro-crack, determining an range of the micro-crack based on a temperature-rising region from the infrared image and the initial coordinate; setting a position corresponding to the range of the micro-crack in the visible image as a new region of interest; obtaining full-field principal tensile strains by a DIC method, and locating an accurate boundary of the micro-crack based on gradient distribution of the full-field principal tensile strains; analyzing displacement and strain fields around the micro-crack using the DIC method.

A tension load fixture for applying tension or loading forces to a specimen comprises a pair of tension arms and an imaging device. The pair of tension arms are configured to releasably couple to opposite end regions of a specimen and to apply tension or loading forces to the specimen. The specimen is configured to be positioned between the pair of tension arms and defines a notch between the opposite end regions of the specimen. The notch extends from a side of the specimen to a middle region of the specimen. The imaging device is configured to capture one or more images of the middle region of the specimen and is configured to rotate about a central axis of the tension load fixture that is proximate to the middle region of the specimen to facilitate generation of a three-dimensional image of the middle region of the specimen as the specimen is subjected to tension or loading forces.

In an aspect, there is a method of determining allowable defects for a composite component comprising identifying at least one wrinkle characteristic of a composite component wrinkle defect; making a first plurality of specimens each having a predetermined wrinkle defect representative of the composite component wrinkle defect; measuring each of the predetermined wrinkle defects in the first plurality of specimens for at least one performance metric to generate performance data; and generating an allowable wrinkle defect profile based on the performance data from the first plurality of specimens. In other aspects, there are methods of making a specimen with a predetermined wrinkle defect.

A method for determining characteristics of a crack detected in a material, comprising: determining initial mechanical loads applied to the material, applying a plurality of crack-opening mechanical loads to the material, each opening mechanical load being a linear combination of the initial mechanical loads, and measuring the relative displacement of the first point with respect to the second point induced by each opening mechanical load, applying a plurality of crack-closing mechanical loads to the material, each closing mechanical load being a linear combination of the initial mechanical loads, and measuring the relative displacement of the first point with respect to the second point induced by each closing mechanical load, and estimating the direction of the crack as a function of the amplitude of each opening and closing mechanical load applied to the material and of the measured relative displacements.