Abstract: A detection device includes a frame body and a main pipe positioning assembly, a branch pipe positioning assembly, and a first driving assembly disposed on the frame body. One side of the frame body is provided with an opening. The branch pipe positioning assembly is disposed inside the opening. The first driving assembly adjusts the branch pipe positioning assembly, so that the branch pipe positioning assembly is adapted to positions of the two branch pipes. During detection, the branch pipes are located in the opening, the main pipe positioning assembly connects two ends of the main pipe, and the branch pipe positioning assembly connects the two branch pipes. Two limiting members are slidably disposed on the frame body to open and close the opening, and the limiting members abut against an outer wall of the main pipe, such that the main pipe is located inside or outside the opening.

Abstract: 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 Tm?c model for characterizing the propagation of short cracks and long cracks, where the Tm?c model is used for representing the growth rate of short cracks and long cracks.

Abstract: 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 Tm?c model for characterizing the propagation of short cracks and long cracks, where the Tm?c model is used for representing the growth rate of short cracks and long cracks.