The present application provides a device for detecting a defect in a steel cord ply. The device is configured to obtain an enhanced magnetic field signal of the steel cord ply and detect a defect of the steel cord ply based on the enhanced magnetic field signal. The device includes a magnetic field unit including a permanent magnet configured to generate a background magnetic field; a signal obtaining unit configured to generate an enhanced magnetic field signal of a steel cord ply based on a plurality of first magnetic field signals and a plurality of second magnetic field signals; and a defect detecting unit configured to detect a defect of the steel cord ply based on the enhanced magnetic field signal, wherein the defect detecting unit includes an AD converting module, a signal processing module, a defect detecting module, a display module, and a control module.

Interface surfaces of mechanical system components may comprise one or more radiographic markers. A radiographic marker may comprise a marker material having a radiopacity greater than a radiopacity of a parent material of a mechanical system component that comprises that radiographic marker. Mechanical systems comprising one or more radiographically-marked components may be radiographically imaged to determine wear, damage, and/or other conditions.

To easily detect a crack having occurred in a steel material. A current measurement device measures a value of a current flowing through a target steel material that is immersed in an electrolyte aqueous solution and applied with tensile stress while subjected to hydrogen charging, and a device for detecting the occurrence of a crack or the like uses the measured current value to determine the occurrence of a crack in the target steel material when the amount of change in the current flowing through the target steel material, the change rate of the amount of change in the current, or the change rate of the change rate of the amount of change in the current exceeds a threshold value. The device for detecting the occurrence of a crack or the like determines the occurrence of a crack in the steel material when the change rate of the change rate of the amount of change in the current is less than a negative value of an absolute value of the threshold value, and determines the occurrence of fracture in the steel material when the change rate exceeds the absolute value of the threshold value.

Disclosed are a hole expansion ratio testing device, a hole expansion ratio testing method, and an operation program. The hole expansion ratio testing device includes a chucking unit configured to chuck a plate member having a hole, a punching unit inserted into the hole and configured to expand the hole, an image acquisition unit configured to acquire an image of the hole expanded by the punching unit, and an analysis unit configured to extract an interest area corresponding to the hole from the acquired image, linearize the interest area, and provide information on a crack as a blob changes due to the linearization.

Disclosed are a hole expansion ratio testing device, a hole expansion ratio testing method, and an operation program. The hole expansion ratio testing device includes a chucking unit configured to chuck a plate member having a hole, a punching unit inserted into the hole and configured to expand the hole, an image acquisition unit configured to acquire an image of the hole expanded by the punching unit, and an analysis unit configured to extract an interest area corresponding to the hole from the acquired image, linearize the interest area, and provide information on a crack as a blob changes due to the linearization.

A method for characterizing propagation of metallic short cracks and long cracks includes: acquiring crack tip opening displacement in a metallic notched sample under cyclic loading; acquiring crack tip opening displacement amount caused by a single monotonic tensile in the notched sample, and crack tip opening displacement caused by monotonic tensile in the notched sample under a maximum far-field stress; and based on an original Shyam model, constructing, according to the crack tip opening displacement amount and the crack tip opening displacement by obtaining yield strength of metals, a T.sub.m.sub.c model for characterizing the propagation of short cracks and long cracks, where the T.sub.m.sub.c model is used for representing the growth rate of short cracks and long cracks.

A method for characterizing propagation of metallic short cracks and long cracks includes: acquiring crack tip opening displacement in a metallic notched sample under cyclic loading; acquiring crack tip opening displacement amount caused by a single monotonic tensile in the notched sample, and crack tip opening displacement caused by monotonic tensile in the notched sample under a maximum far-field stress; and based on an original Shyam model, constructing, according to the crack tip opening displacement amount and the crack tip opening displacement by obtaining yield strength of metals, a T.sub.m.sub.c model for characterizing the propagation of short cracks and long cracks, where the T.sub.m.sub.c model is used for representing the growth rate of short cracks and long cracks.

To estimate a fracture starting point of steel due to hydrogen embrittlement with high accuracy. A steel fracture starting point estimation device includes a hydrogen concentration distribution calculation unit adapted to calculate a hydrogen concentration distribution in steel-to-be-estimated when the steel fractures due to hydrogen embrittlement; a local critical hydrogen content calculation unit adapted to calculate critical hydrogen content at which the steel-to-be-estimated fractures due to hydrogen embrittlement; and a fracture starting point estimation unit adapted to read the hydrogen concentration distribution out of a storage unit. To estimate, calculate, from the hydrogen concentration distribution, a location in the steel in which hydrogen concentration of the critical hydrogen content is distributed, and designate the location in the steel as the fracture starting point of the steel-to-be-estimated.

To estimate a fracture starting point of steel due to hydrogen embrittlement with high accuracy. A steel fracture starting point estimation device includes a hydrogen concentration distribution calculation unit adapted to calculate a hydrogen concentration distribution in steel-to-be-estimated when the steel fractures due to hydrogen embrittlement; a local critical hydrogen content calculation unit adapted to calculate critical hydrogen content at which the steel-to-be-estimated fractures due to hydrogen embrittlement; and a fracture starting point estimation unit adapted to read the hydrogen concentration distribution out of a storage unit. To estimate, calculate, from the hydrogen concentration distribution, a location in the steel in which hydrogen concentration of the critical hydrogen content is distributed, and designate the location in the steel as the fracture starting point of the steel-to-be-estimated.

A method for evaluating a crack in a metal member comprises a first removal step (S10) and a second removal step (S20). In the first removal step (S10), a step for electrolyzing a metal member having an oxide scale formed on a surface thereof, a step for acquiring an image of the oxide scale as a first image, and a step for determining whether or not a scale crack has occurred are repeated until occurrence of a scale crack is determined. In the second removal step (S20), a step for electrolyzing the metal member having the scale crack, a second image acquisition step for acquiring an image of the oxide scale as a second image, and a second determination step for determining whether or not the scale crack has disappeared are repeated until disappearance of the oxide scale is determined.