Abstract: A sub-pixel displacement measurement method based on a Tikhonov regularization, including the following steps: collecting two images before a structure is deformed, and recording the two images as reference images; collecting an image after the structure is deformed, and recording the image as a target image; extracting grayscale matrices in the two reference images, recording the grayscale matrices as f0 and f1, and calculating a noise level parameter ? of the two reference images: taking a pixel point to be measured as a center point, extracting a square region in the target image, recording a grayscale matrix of the square region as g, and using a Tikhonov regularization method to separately obtain grayscale gradient matrices of the square region along an x direction and along a y direction; and calculating a sub-pixel displacement of the structure by using the grayscale gradient matrices.

Abstract: A high-precision transient energy response prediction method for a complex structure, including: taking a time dependent term (formula I) of energy transfer between subsystems into account; establishing a transient power balance equation of each subsystem of the structure by combining with a loss factor matrix ? n of the complex structure; and given initial boundary parameters, adopting fourth-order and fifth-order Runge-Kutta algorithms to calculate transient energy response of each subsystem of the structure. The present invention establishes a more complete transient energy balance equation for each subsystem of the complex structure by taking the time dependent term of energy transfer between the subsystems of the complex structure into account, thereby significantly improving the prediction precision of the current transient statistical energy analysis method in the transient energy response prediction, and expanding the research scope of the current transient statistical energy analysis method.

Abstract: A dynamic response analysis method based on a dual-mode equation in a random noise environment includes the following steps: (1) dividing a structure and an acoustic cavity in an acoustic-structural coupling system into different subsystems; (2) calculating modes of the structural subsystems and the acoustic cavity subsystems; (3) calculating inter-mode coupling parameters in adjacent subsystems; (4) establishing a dual-mode equation of the coupling system; (5) by means of pre-processing, obtaining a cross power spectrum of generalized force loads applied on the subsystem modes under the action of a random load; (6) calculating the dual-mode equation to obtain cross power spectra of all participation factors of all modes; and (7) by means of modal superposition, calculating a random acoustic-structural coupling response of the system.

Abstract: A method of constructing a dynamic shear constitutive model for a fiber-reinforced composite material includes the following steps: 1. carrying out shearing experiments on the fiber-reinforced composite material under a plurality of strain rate loading working conditions to obtain a load-displacement curve under each working condition; 2. combining a Weibull damage model with a viscoelastic model to deduce a load-displacement relationship to be fitted including a Weibull damage distribution; 3. constructing a multi-curve least-squares objective function according to the load-displacement curve and the load-displacement relationship; 4. using a genetic algorithm to obtain initial values of parameters to be fitted, and searching around the obtained initial values of the parameters through a trust-region method to finally obtain a high-precision parameter value and a determined load-displacement relationship including the Weibull damage distribution; and 5.