2 results about "Propagation equation" patented technology

The application provides a gear fatigue crack propagation life calculation method and system considering random dynamic load, and the method is as follows: a local plane coordinate system is established at a crack tip, and a crack propagation equation is constructed; time-varying mesh stiffness containing a tooth root crack feature is calculated; a vibration differential equation of a gear mesh pair is constructed and solved, and dynamic meshing forces of the gear pair under different crack states are obtained; the dynamic meshing forces of the gear pair under different crack states are processed, and a load spectrum is prepared, and variable amplitude load data with multi-periodicity are obtained; the variable amplitude load data are taken as boundary conditions, crack propagation is simulated, gear fatigue crack propagation data are read from a finite element data file; stress intensity factors are calculated based on the gear fatigue crack propagation data; and fatigue crack propagation life is estimated based on the Paris formula and the stress intensity factors. The method can improve the reliability and fatigue crack propagation life of the gear, improve the safety of equipment, and reduce maintenance costs.

The application discloses a high-speed printed circuit board differential pair transmission path equal-length matching optimization method and belongs to the technical field of signal integrity modeling and simulation. The method comprises the following steps: constructing a multi-conductor transmission line model containing a reference conductor and extracting a per-unit-length parameter matrix; judging structural uniformity and symmetry; introducing a spatially-varying local modal basis and a continuous modal coupling term for describing the modal conversion caused by the gradual change of the structure; calculating the propagation time delay difference of two signal paths and constructing a phase calibration operator; integrating the modal conversion and the time delay mismatch effect into a unified propagation equation for solving; and applying the phase calibration operator to align the voltage and current at the recoupling reference surface, so that the equivalent differential mode impedance is finally calculated. The application integrates the combined effects of modal conversion and time delay mismatch for integrated modeling, and significantly improves the impedance simulation accuracy of the recoupling area of the differential pair serpentine compensation structure.