9 results about "Joint sample" patented technology

The present application relates to the technical field of material testing, in particular to a sample and tool for testing Z-direction fatigue performance of laminated composite material, the sample is axisymmetric dumbbell-shaped, comprising a middle test section and two end holding ends, and the bonding interface is located in the test section; the diameter of the test section is 5-10 mm, and the diameter of the holding end is greater than or equal to 2 times the diameter of the test section; the thickness of the holding end is not less than 5 mm, and the axial distance from the inner side end face to the bonding interface is not less than 3 mm, so that the interface is ensured to be in a uniform stress area; the transition area is smoothly connected by a circular arc with a radius of greater than or equal to 2 mm. The present application can accurately and repeatedly characterize the Z-direction interface fatigue performance on a conventional fatigue testing machine, and solves the problem that the traditional composite material joint sample cannot test the real joint interface performance.

The invention relates to the technical field of diffusion welding head sample preparation, in particular to a thin plate lap joint diffusion welding head sample preparation method which comprises the steps that firstly, according to the thickness of a thin plate to be welded and the compression amount set by a diffusion welding process test, lap joint clamp structure size parameters are designed; the two thin plates to be welded are assembled to the two lap joint clamps correspondingly; one of the two lap joint clamps rotates by 180 degrees around the built-in opening of the lap joint clamp and then is buckled on the other lap joint clamp to achieve lap joint fixing of the two to-be-welded sheets, finally diffusion welding is conducted on the lap joint clamp provided with the to-be-welded sheets, and a sheet lap joint diffusion welding head sample is obtained. According to the method, through the lap joint clamp, the preparation quality of the lap joint diffusion welding joint sample is guaranteed, the original defects of the diffusion welding joint are reserved due to the fact that the joint does not need post-welding machining, and therefore effective evaluation on the performance of the thin plate laminated diffusion welding joint can be improved.

The embodiment of the specification provides a two-dimensional joint roughness coefficient nonlinear determination method and device based on GBDT, wherein the method comprises the following steps: obtaining three-dimensional point cloud data of rock joint sample surface topography through scanning; performing simplification processing on the three-dimensional point cloud data and exporting the three-dimensional point cloud data as a CSV file; calculating joint surface topography statistical parameter values and taking the joint surface topography statistical parameter values as machine learning model features; obtaining wall rock strength JCS of the rock joint sample through field experiments, performing direct shear test on the structural surface sample under a certain normal pressure, determining the basic internal friction angle and the peak shear strength of the structural surface sample, and calculating the JRC of the joint surface according to the JRC-JCS shear strength model; establishing a training set and a test set; establishing a GBDT model with a decision tree as a base learner, training and adjusting the model by using the training set, obtaining the trained GBDT model, inputting the test set into the trained GBDT model for testing, and finally taking the average value of the predicted values as the JRC value of the joint surface predicted by the model.

The invention discloses a T-shaped joint drop hammer impact test device and an impact test method thereof.The device comprises a frame body, a fixed base is arranged at the bottom in the frame body, a T-shaped joint sample is connected to the fixed base, and an impact assembly, a locking assembly and a lifting assembly are arranged above the T-shaped joint sample; the lifting assembly is connected with the impact assembly through a locking assembly, and the locking assembly is provided with a locking position and a releasing position; when the locking assembly is located at the locking position, the lifting assembly is in locking linkage with the impact assembly, and when the locking assembly is located at the releasing position, the impact assembly is separated from the lifting assembly for impact; the impact assembly is provided with an acceleration sensor and a stress sensor, and the signal output end of the acceleration sensor and the signal output end of the stress sensor are both connected with the signal input end of the PLC. According to the invention, the drop hammer impact test of the T-shaped joint web can be realized, and the high-speed impact test of different positions of the T-shaped joint web under different impact loads can be realized.

The invention provides a method for predicting a stress field of a dissimilar steel joint under a peak regulation working condition of a thermal power generating unit, which belongs to the field of electric power engineering and comprises the following steps: measuring residual stress of a welded dissimilar steel joint sample; establishing a welding state dissimilar steel joint geometric model, setting welding process parameters, calculating a residual stress field, calibrating the geometric model, and obtaining a residual stress prediction model and residual stress distribution; establishing a pipeline geometric model, assigning the residual stress distribution as an initial stress field to the pipeline geometric model, and applying temperature and internal pressure as boundary conditions to the pipeline geometric model to obtain stress distribution characteristics of the dissimilar steel joint; taking the temperature and the internal pressure as input, taking the stress distribution characteristics as output labels, and training a machine learning agent model; collecting the temperature and pressure of the pipeline in real time, inputting the temperature and pressure into the trained machine learning agent model, and predicting the stress distribution of the dissimilar steel joint through active learning; the invention also provides a prediction system. And the prediction precision of the dissimilar steel joint stress field is improved.

The present invention relates to a method for evaluating the atmospheric corrosion resistance of steel welded joints. The present invention utilizes a scanning electrochemical workstation to perform potential scanning on the surface of a welded joint sample, thereby characterizing the corrosion potential of various parts of the welded joint sample for studying the corrosion resistance of the welded joint sample. The welded joint sample is pretreated with solutions of different simulated atmospheric environments to simulate a thin liquid film formed on the surface of the sample under the corrosive environment, thereby studying the corrosion resistance of the welded joint under different atmospheric environments and providing a corrosion resistance basis for the selection of welding materials and the formulation of welding process parameters. The welded joint is studied to quickly and accurately evaluate the corrosion resistance of various areas of the welded joint. The corrosion mechanisms of the welded joint in different atmospheric environments are different. Different thresholds are set according to the severity of the corrosive environment and while fully considering the weld heat affected zone as a weak position of the welded joint, so that the evaluation results are more accurate and reasonable.

The application discloses a butt welding joint modeling simulation method based on shell elements, comprising the following steps: based on microhardness testing, dividing a butt welding joint sample into a weld zone, a heat affected zone and a base material zone, and calibrating hardening model parameters for each zone; establishing a shell element model, assigning the hardening model parameters to corresponding shell elements, and correcting the flow stress of the shell elements in the weld zone by the excess height, wherein the correction coefficient K is the maximum load ratio of the reserved excess height sample and the milled excess height sample; defining a nonlinear damage accumulation fracture criterion for the shell elements, wherein the equivalent plastic failure strain is a function of the stress triaxiality; and introducing a grid dependency factor to correct the equivalent plastic failure strain. The application solves the problem of bearing capacity prediction distortion of the shell element model by microhardness partitioning and excess height correction, and realizes accurate prediction of the fracture behavior under a multi-stress state by the stress triaxiality related fracture criterion and grid regularization, and is suitable for large-scale engineering simulation such as vehicle collision.

The invention discloses a fatigue test method, device and system for a welding seam of a T-shaped joint, and the method comprises the steps: building a quantitative relation between a loading load acting on the free end of a web plate and the stress at a weld toe according to the geometric dimension of a T-shaped joint sample; according to the stress ratio specified by the fatigue test and the stress range at the weld toe, the average loading load and the load amplitude are calculated based on the quantitative relation; fixedly connecting the T-shaped joint weld fatigue test device to a fatigue testing machine, and fixedly connecting the T-shaped joint sample to the working surface of the T-shaped joint weld fatigue test device; and setting load parameters as the average loading load and the load amplitude in a fatigue testing machine, applying an alternating load to the free end of the web of the T-shaped joint sample to carry out a fatigue test, and recording the cycle index when the weld joint of the T-shaped joint sample is in fatigue failure. According to the invention, the test detection of the fatigue life of the welding seam of the T-shaped joint can be realized, and the obtained fatigue life provides support for optimization of a welding structure and a welding process of engineering machinery.

The invention discloses a welding joint micro-region dislocation density measuring method based on grain orientation, and belongs to the field of welding. The method comprises the following steps: firstly, providing a zirconium alloy joint sample, carrying out EBSD analysis on a detection area of the joint sample, and determining a grain structure and grain orientation; crystal grains with orientation are selected, and a TEM sample is prepared through FIB; and respectively representing dislocation parameters of a-type dislocation and c-type dislocation in the TEM sample by using the TEM, and counting to obtain the average dislocation density in a plurality of crystal grains in the detection area as the dislocation density of the detection area. According to the method, the dislocation in the welding joint microcell can be directly represented, the imaging quality when the dislocation density is measured through the TEM method is effectively improved, and the efficiency and accuracy of dislocation density measurement are improved.