Study On The Optimization Of Multi-point Measurement By Modal Analysis To Identify Cable Force Of Short Cable

Most of the cable force identification methods currently studied in the short cable are the empirical formula method.In the process of identifying the cable force,it is necessary to know the bending stiffness of the short cable and calculate the cable length,etc.However,these data cannot be accurately given in the actual cable force test,especially in the late cable force detection and monitoring.The short cable force identification method studied in this paper is a new method based on modal analysis,and does not need to know the above parameters.Based on the previous researches on the specific methods of theoretical derivation and identification of this method,this paper makes a detailed study on the sensor placement points used to acquire the shape data during the cable force identification process.Previous studies have found that the location and number of multiple measuring points used to acquire modal information during the cable force identification process have a certain influence on the modal analysis to identify the short cable force.The specific performance is that the data collected on the optional measuring point group can not easily and accurately fit the multi-order mode,which results in the unsatisfactory effect of cable force recognition.On the other hand,the number of measuring points is as good as possible from the perspective of accurately fitting the vibration mode,and the less the better from the point of view of practical application economics and convenience.Therefore,it is necessary to optimize the specific number of multiple measuring points and the arrangement position scheme.In this paper,the effective independent method,modal confidence method and effective independent and modal confidence synthesis method are chosen as the optimization algorithm theory of our research,and the corresponding optimization program is written by MATLAB.These three methods are based on the modal independence optimization method,which can ensure the modal of the point identification has better independence and easy to distinguish the multi-order modal.The ANSYS model of twelve kinds of short cables was established.The vibration mode extracted by modal analysis was used as the theoretical vibration mode,and the optimized program was used to obtain the optimization scheme of six to ten measurement points.The short-term model of each specification is excited by whitenoise to simulate the working state of the actual short-term cable under the action of the environment,and the displacement time-history data of each measuring point corresponding to each optimization scheme is extracted,and a series of modal-based analysis is performed through the data.The method performs cable force identification and obtains the identification cable force of the corresponding scheme.Compare and analyze the effect of cable strength identification of each program,and select the recommended scheme.Use the recommended scheme to identify the cable force of each comparison test and verify the applicability of the recommended scheme.Compared with the random point measurement scheme with the same number of points,the cable force identification is used to verify the necessity of point optimization.A three-stage,two-end consolidation model is established to simulate that the stiffness of the casing portion at both ends of the actual short cable is larger than that of the middle portion.In this model,the numerical simulation experiment is carried out.The modal analysis method and several empirical formula methods are used to identify the cable force,and the effects and characteristics of the two methods are compared and analyzed.According to the results of each comparison test,considering the necessity of the number of measuring points and the universal applicability of the position of the measuring points,the recommended scheme is finally obtained according to the law of the modal confidence method six measuring point scheme,and the proportional measurement applicable to the general cable is obtained.Point location.A series of comparative tests have shown that the recommended scheme is widely applicable to various specifications.Multiple point optimization is necessary and effective.Compared with the empirical formula method,the method of cable force identification has a better effect and a wider application range.In addition,the optimized measuring point scheme can simplify part of the process of cable force identification,and the cable force identification accuracy is higher,achieving an ideal optimization effect.The test method for identifying short cable force based on modal analysis is improved by multi-measurement optimization,which has certain practical value and practical significance.