10 results about "Interfacial fracture" patented technology

The invention discloses a method for predicting mechanical properties of ultra-high performance concrete, particularly relates to the technical field of dynamic property analysis of building materials, and aims to solve the problem that sudden brittle failure of materials cannot be accurately predicted under impact and explosion loads in the conventional method. The method comprises the following steps: calculating a macroscopic stress-strain response based on a continuum mechanical equation by acquiring a material ratio parameter and a dynamic load condition; constructing topological features through the strain energy entropy change rate to locate a damage area; determining an interface debonding energy threshold value and a crack growth rate of the damaged area in combination with interface fracture mechanics; utilizing the law of conservation of energy to establish dynamic correlation between interface debonding energy and strain energy density; when the crack growth rate exceeds an interface debonding energy threshold value, correcting macroscopic response data of a sudden stress drop interval based on the dynamic association relationship; the cross-scale coupling of a microscopic damage mechanism and a macroscopic mechanical behavior is realized, and the prediction precision under a dynamic load is remarkably improved.

The present application relates to the field of metal composite plate explosion welding, and provides a sample, a tool and a method for Z-direction fatigue test of an explosion composite joint, the sample comprising at least a top layer and a bottom layer, and the sample comprising at least one interface, the sample comprising: a circumferential boss part composed of an upper part of the top layer; a central column part arranged below the circumferential boss part, the central column part comprising at least a lower part of the top layer and the bottom layer; a tapered transition part arranged between the circumferential boss part and the central column part; an upper central through hole opened downward from the top of the sample and extending to below the interface to be tested by more than 1mm; and a lower central through hole in communication with the upper central through hole. The sample for Z-direction fatigue test of the explosion composite joint, one, controls the fatigue failure surface at the interface, and realizes accurate determination of the Z-direction fatigue performance of the explosion composite joint; two, does not easily cause interface fracture during installation; and three, can satisfy tensile-tensile fatigue, tensile-compressive fatigue and compressive-compressive fatigue tests.

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).

This invention discloses an adaptive analysis method for the defect elimination zone of a glass through-hole (TGV) structure, comprising: acquiring process parameters of the TGV structure, determining the material properties of the TGV structure, and constructing an input variable set; determining different levels of each process parameter in the input variable set to obtain the configuration of the TGV structure, calculating the maximum principal stress response of the TGV structure, and calculating the contribution rate of each process parameter in the input variable set; selecting the optimal configuration of the TGV structure corresponding to the maximum principal stress response, determining the morphological parameters, load type, and interface fracture behavior parameters of the pre-crack in the TGV structure, and calculating the fracture mechanical properties of the crack tip at various locations of the TGV structure using the contour integral method, thereby obtaining the defect elimination zone range of the TGV structure. This invention can effectively solve the problems of low process trial-and-error efficiency, poor collaborative design, and low product quality yield in glass through-hole structures.

The application discloses a composite material fracture energy calculation method considering reinforcement-matrix interface dispersion, and comprises the following steps: S1, a matrix crack fracture energy model is established; S2, a reinforcement-matrix interface fracture energy model is established; S3, a composite material fracture control equation model is established; S4, a composite material critical energy release rate is modified; S5, the interface phase field, the displacement field and the crack phase field in the composite material fracture control equation are discretized by using the finite element method, and an incremental iteration is carried out, so that the crack propagation in the composite material considering the interface dispersion is calculated. Through the adoption of the phase field model, the advantages of realizing the micro-to-macro multi-scale simulation are utilized, the properties of the interface in the composite material are associated with the properties of the matrix, that is, the interface crack propagation and other fracture properties of the composite material under the action of the load are dispersed to the surrounding matrix in the form of a continuous exponential function, and a mechanical model for more accurately predicting the mechanical behavior and fracture evolution of the composite material is established.

The invention relates to the field of metal composite plate explosive welding, and provides a sample, a tool and a method for Z-direction fatigue testing of an explosive composite joint, the sample at least comprises a top layer and a tail layer, the sample at least comprises an interface, and the sample comprises a circumferential boss part formed by the upper part of the top layer; the central cylinder part is arranged below the circumferential boss part, and the central cylinder part at least comprises a lower part of a top layer and a tail layer; the conical transition part is arranged between the circumferential boss part and the central cylinder part; the upper central through hole is formed downwards from the top of the sample and extends to a position which is larger than 1mm below an interface to be tested; and the lower central through hole is communicated with the upper central through hole. According to the Z-direction fatigue test sample for the explosive composite joint, firstly, a fatigue failure surface is controlled at an interface, so that the accurate judgment of the Z-direction fatigue performance of the explosive composite joint is realized; interface fracture is not prone to being caused in the installation process; and 3, tension-tension fatigue, tension-compression fatigue and compression-compression fatigue tests can be met.

The invention discloses a one-dimensional interface fracture driving force pure modal distribution method based on a double-cantilever camber beam. The method comprises the following steps: defining a geometric configuration and a load condition of a double-cantilever camber beam model according to an application scene of a composite material; according to the geometrical configuration and the load condition, calculating interlayer shearing force and interlayer opening force of the non-cracking area of the double-cantilever camber beam; calculating an equivalent load of the crack tip of the double-cantilever camber beam model by combining an equivalent superposition principle based on the interlayer shearing force and the interlayer opening force; according to the equivalent load of the crack tip of the double-suspension-arm camber beam model, the total energy release rate of the double-suspension-arm camber beam model is calculated; and distributing the one-dimensional interface fracture driving force mode into a pure I type and a pure II type based on the total energy release rate in combination with the equivalent load of the crack tip of the double-cantilever camber beam model. According to the method, the energy of each component can be quickly and accurately predicted, finite element analysis is not needed, and the time cost is saved.