11 results about "Modal strain energy" patented technology

The invention discloses a marine environment pile foundation damage identification method based on optical fiber distributed strain monitoring, and belongs to the technical field of structural health monitoring and ocean engineering. The marine environment pile foundation damage identification method comprises the steps that distributed optical fiber sensors are evenly distributed in the axial direction of a pile foundation and used for strain monitoring; acquiring strain response data of the pile foundation along the pile length under the action of the wave force load through a distributed optical fiber demodulator; identifying modal characteristic parameters of the pile foundation structure by applying a random subspace identification algorithm, wherein the modal characteristic parameters comprise modal frequency and modal shape; calculating modal strain energy based on the modal shape, and obtaining a modal strain energy distribution diagram; identifying a damage area, judging whether a set threshold value is exceeded or not by comparing the change of the modal strain energy between the monitoring state and the reference state, judging the damage, and obtaining a damage identification result. The method provided by the invention has the advantages of high spatial resolution, high recognition precision, good environmental adaptability, accurate positioning, high automation, wide applicability and the like.

The invention discloses an offshore wind turbine structure damage identification method and system based on sparse sensor arrangement, and the method comprises the steps: collecting the acceleration time sequence data of each measurement point of an offshore wind turbine structure in real time; inputting the collected acceleration time series data into an FA-MPI method for analysis, and obtaining the modal strain energy change rate of each measuring point as a damage index; pre-training the SE-CMA-CNN model by using the constructed data set to optimize network parameters, and storing model parameters with optimal performance; fA-MPI analysis is carried out on the measurement point acceleration time sequence data of the to-be-identified structure to obtain a corresponding modal strain energy change rate, and standardization processing is carried out; and importing standard input data into the trained SE-CMA-CNN model, and outputting a damage position identification result and a damage degree quantitative evaluation result of the offshore wind turbine structure. According to the method, the accuracy, robustness and engineering applicability of damage detection can be improved in a complex marine environment with limited measuring points and strong noise interference.

The invention relates to a damping optimization and design method for a fiber-reinforced composite lattice sandwich structure, which belongs to the technical field of vibration reduction and noise reduction of composite lattice sandwich structures. The invention solves the problems of low accuracy of theoretical prediction of the damping performance of composite lattice sandwich structures, and poor optimization effect of geometric parameters based on damping performance. The invention obtains the stress and strain components of each unit of the composite lattice sandwich structure through modal analysis, and solves the modal damping of the structure in combination with the modal strain energy method, thereby providing a set of methods for accurately predicting the damping performance of composite lattice sandwich structures, and can perform structural optimization design based on the damping prediction results, thereby improving the optimization effect, and providing a basis for the design of fiber-reinforced composite lattice sandwich structures with vibration reduction requirements. The method of the invention can be applied to the technical field of vibration reduction and noise reduction of composite lattice sandwich structures.

The application discloses a kind of marine environment pile foundation damage identification method based on optical fiber distributed strain monitoring, belong to structural health monitoring and ocean engineering technical field, comprising: along the axial uniform distribution of distributed fiber optic sensor in pile foundation, for strain monitoring;Strain response data of pile foundation under the action of wave load along pile length is collected by distributed fiber optic demodulator;Modal characteristic parameters of pile foundation structure are identified by random subspace identification method algorithm, and modal characteristic parameters include modal frequency and modal shape;Modal strain energy is calculated based on modal shape, and modal strain energy distribution diagram is obtained;Damage area is identified, whether it is judged to exceed the set threshold by comparing the change of modal strain energy in monitoring state and reference state to determine damage, and damage identification result is obtained.The application has the advantages of high spatial resolution, high identification accuracy, good environmental adaptability, accurate positioning, high automation and wide applicability.

The application discloses a beam structure damage identification method of an exponential optimization modal strain energy method, and steps are as follows: (1) a plurality of mode shape curves before and after beam structure damage are obtained through dynamic testing respectively; (2) the mode shape curvature before and after beam structure damage is calculated by using a central difference method, and then the mode shape curvature curve after damage is adjusted by using an optimal matching method; (3) the mode shape curvature before beam structure damage is subtracted from the adjusted mode shape curvature after damage for a statically determinate structure, and damage positioning is carried out by using mode shape curvature difference curve mutation synthesis for a statically indeterminate structure; (4) the mode shape curvature of a unit is calculated by using the mode shape curvature before beam structure damage and the adjusted mode shape curvature, and damage degree quantification is carried out by using the exponential optimization modal strain energy method. The application can accurately identify the damage position and damage degree of a beam structure, is suitable for different beam structure damage identifications, provides an effective new method for beam structure damage identification, and can be applied to bridge damage evaluation.

The application discloses a pile foundation positioning and quantitative damage identification method and device and a storage medium, and belongs to the technical field of engineering detection. The method comprises the following steps: dividing a pile body into a plurality of pile body sections, and acquiring acceleration time history data of nodes at both ends of each pile body section; performing modal analysis on the acceleration time history data, and estimating modal shapes of each node; calculating modal strain energy residual variables of each pile body section by using the modal shapes; drawing a curve of the modal strain energy residual variables of each pile body section according to the division order, and positioning a pile body section corresponding to a protruding position of the curve as a damage section; establishing a numerical relationship between the modal strain energy residual variables and the pile body integrity, and converting the modal strain energy residual variables of the damage section into the pile body integrity based on the numerical relationship to quantitatively judge the damage degree. The application has the advantages of small amount of measured data and calculated amount, high identification precision, and convenient application in actual engineering.

The application provides a large-span steel structure closed loop analysis method and system, the analysis method comprises the following steps: constructing a finite element model and a design parameter space, identifying key design parameters and key regions affecting the first N modal strain energy of the structure through initial sensitivity and modal analysis, and establishing a mapping relationship between the two; according to the parameter sensitivity contribution, a non-uniform sampling strategy is formulated, the sampling is encrypted in the high sensitivity parameter subspace, an initial sample set is generated, based on the sample and the finite element response, a hierarchical mixed kernel Kriging surrogate model containing a global long-range kernel and a multi-region local short-range kernel is constructed, the local kernel weight increases as the input point approaches the high sensitivity region, the iteration termination and the performance limit state are set, the composite point adding criterion integrating the prediction variance, the limit state distance and the cross-validation error is used to iteratively update the sample and the model, and after the condition is met, the structure performance analysis is completed by using the surrogate model.

The present application provides a method for detecting the damping loss factor of a transmission pipeline, which relates to the technical field of material mechanics. The method comprises: obtaining the measured motion response and strain response of the target cylindrical shell based on a preset vibration excitation and load applied to the target cylindrical shell; calculating the target kinetic energy of the target cylindrical shell based on the motion response, and calculating the target strain energy of the target cylindrical shell based on the strain response; calculating the Lagrangian according to the target kinetic energy and target strain energy; calculating the total energy dissipated by the target cylindrical shell through the form according to the target kinetic energy and the specific damping capacity of the target cylindrical shell; calculating the damping loss factor of the target cylindrical shell in each direction according to the Lagrangian, the total energy dissipation, and the target strain energy; and calculating the structural damping loss factor of the target cylindrical shell based on the damping loss factors in each direction according to the modal strain energy method. The present application can improve the accuracy of the damping loss factor calculation of cylindrical shell materials.

The invention discloses a beam structure grading damage identification method based on an additional mass block and a genetic algorithm. The method comprises the following steps: S1, collecting fifth-order modal shape data of a damaged beam structure; s2, establishing a finite element model of the damage-free beam structure by utilizing finite element analysis software, and performing modal analysis on the damage-free beam structure; s3, respectively calculating unit modal strain energy before and after the beam structure is damaged by utilizing a formula; s4, the average unit modal strain energy change rate of the first five orders of the damaged structure is calculated through a formula, a primary positioning result of the damaged position is determined according to the average unit modal strain energy change rate, and a preliminary damaged area is obtained; and S5, if the primary positioning result in the step S4 is a single clear damage position, completing damage positioning.

The application provides a machine tool column structure optimization method based on finite element simulation, and relates to the technical field of machine tool column structure optimization.The application accurately defines the key laying area of the constraint layer damping which is most effective in inhibiting resonance according to the threshold screening and region growing algorithm in the inner wall of the column based on the identified risk resonance mode, the modal strain energy cloud diagram and the mode shape animation, and establishes a parameterized model to realize the coupling optimization of the thickness, so that the precise positioning and on-demand distribution of the damping laying are realized.The utilization efficiency and damping effectiveness of the damping material are fundamentally improved by concentrating the limited damping material in the local area with the most dense vibration deformation energy and strain energy, material waste and invalid weight increase are avoided, and in combination with the parameterized optimization, the design space for reducing the damping layer coverage area, reducing the cost and process complexity is provided under the premise of ensuring the dynamic performance.

The invention provides a modal strain energy-based rotor bracket torsional vibration suppression design method and system and a rotor bracket. The method comprises the following steps of S1, collecting actual operation data of a rotor of a range extender generator; s2, carrying out vibration noise simulation analysis on the rotor to determine the significant peak frequency of the vibration response of the rotor; s3, carrying out modal contribution analysis on the rotor to determine a modal shape with significant contribution; s4, the modal strain energy and the swing modal frequency of the position, needing to be optimized, of the rotor are calculated; s5, determining a plurality of related variables, wherein the plurality of related variables form an optimization target set; and S6, calculating numerical values of all related variables meeting the target function in the optimization target set so as to find the optimal structural parameters of the rotor support of the rotor. According to the scheme, the structure of the rotor bracket of the range extender generator can be optimized, the rotor bracket obtained through optimization is proved to be effective in torsional vibration suppression, and the torsional vibration knocking level can be effectively improved.