Damage Locating Vectors-based Damage Identification Technique Research In Mechanical Structures

During the working Period of the mechanical structure,Due to some factors influence,such as external loads incentives,environmental corrosion,material aging and the long-term effects of fatigue loads etc.,will continue to accumulate damage in structure,Local damage in the structure may lead to rapid destruction of the structural integrity,then causing a major security incidents and a huge loss to life and property of the people.Therefore,Determine whether there is damage and locate the damage position in the mechanical structure and ensure the safety and reliability.It is important implications for the safe operation and timely repair of mechanical structures.This paper summarizes the research status of various damage identification methods based on modal parameters and its advantages and disadvantages, describes the principle of distributed FBG strain sensing and the signal feature modeling,and the experimental strain modal analysis theory, describes the derivation of the expression strain flexibility matrix, Depth study the damage locating model of the damage locating vectors (DLVS).In ANSYS Software, simulation analysis of damage identification process on the corners fixed plate structure based on the damage locating vectors,Construct the formation of the strain flexibility matrix of the sheet structure, the difference matrix between the strain flexibility matrix of the intact and damage structure take a singular value decomposition process.Determining the strain of each unit on the finite element model under the load vector of each group,building the rule of the cumulative amount of strain identification (nsi),to locate the single and multiple damages regions on the sheet structure, and investigate the influence of the number of strain monitoring points on the accuracy of identifying damage.In the experiment sheet structure damage,The damage to be prepared by the drill drilling and machines groove cutting, exciting at the center of the plate, with Fiber Bragg grating strain sensors to monitor each measuring point, On the basis of the strain flexibility matrix using the damage locating vectors method to locate the area of a single damage and multiple damages appeared.