4 results about "Interfacial fracture" patented technology

This invention relates to a method for predicting the fracture behavior of the brazing interface of high-nitrogen steel-molybdenum-niobium alloy based on multi-element coupled modeling, comprising: S1, constructing an initial pure metal crystal structure model; S2, optimizing the geometric structure of the model; S3, cutting the model to construct multiple crystal plane models containing different atomic layer thicknesses; S4, performing convergence tests on the multiple crystal plane models respectively; S5, constructing a high-nitrogen steel principal element / brazing filler metal principal element pure metal interface model and a molybdenum-niobium alloy principal element / brazing filler metal principal element pure metal interface model; S6, constructing a realistic brazing interface composite model with multi-element metallurgical interaction characteristics through atomic substitution; S7, calculating interface adhesion work data and electronic structure data to predict the preferential fracture location and fracture mode. The realistic brazing interface model constructed by this invention with multi-element coupled doping can simulate element segregation and phase transformation in actual brazing, quickly infer stress concentration areas and predict fracture modes, significantly shortening the research and development cycle and reducing costs.

The application discloses a cementing cement sheath interface seal loss length prediction method, a program product and equipment, and the method comprises the following steps: determining interface cracking toughness based on mechanical parameters and fracturing fluid performance parameters; determining interface crack propagation rate in each unit well section based on interface crack propagation time in the unit well section and unit well section length; determining interface fracture toughness of the unit well section based on the mechanical parameters and the interface crack propagation rate in the unit well section; determining cementing cement sheath interface seal loss length in the unit well section based on microseismic data, the interface cracking toughness and the interface fracture toughness of the unit well section; and summing up the cementing cement sheath interface seal loss length in each unit well section to obtain the cementing cement sheath interface seal loss length of the to-be-measured fracturing section. The technical scheme provided by the application can improve the accuracy of cementing cement sheath interface seal loss length prediction.

The present application relates to the technical field of non-destructive characterization of composite material interface, and provides a method for characterizing fracture toughness of aircraft composite bonding structure based on nonlinear guided waves, which comprises applying nonlinear guided wave excitation to the bonding structure of the aircraft composite skin and shell to be tested, collecting the first-arriving guided wave signals propagating along the bonding interface in each bonding sample to be tested; performing frequency domain analysis on the first-arriving guided wave signals on each propagation path, extracting the amplitudes of the fundamental frequency component, the second harmonic component and the third harmonic component, calculating the corresponding nonlinear parameters and the normalized nonlinear parameters; solving the corresponding interface evolution index by using the constructed bonding interface fracture toughness characterization model; converting the obtained interface evolution index into interface fracture toughness according to the mapping relationship between the interface evolution index and the type I interface fracture toughness established by experiments, and realizing the non-destructive fracture toughness characterization of the bonding sample to be tested.

The present invention relates to a test specimen (10) having an initial notch (40) extending parallel to the plane P of the specimen throughout the entire width of the test specimen (10), wherein the test specimen comprises three parts arranged longitudinally in a continuous manner: a thin portion (11) having a thickness H0, a thick portion (13) having a thickness H2, wherein H2>H0, and a transitional intermediate portion (12) with a variable thickness H1 located between the thin portion (11) and the thick portion (13). When the test specimen (10) is subjected to a three-point bending test, the initial notch (40) can extend parallel to the plane P into the intermediate portion (12) and possibly into the thick portion (13), wherein a first bearing point (21) is located below the thin portion (11), a second bearing point (22) is located below the thick portion (13), and a load (30) is applied to the thick portion (13) between the first bearing point (21) and the second bearing point (22).