Research On Identification Method Of Dynamic Balance Parameters Of Composite Material Rotating Shaft

Carbon Fiber Reinforced Plastic(CFRP)has the advantages of high specific strength,high specific modulus,large damping ratio and fatigue resistance.The drive shaft made of carbon fiber composite material is especially suitable for long span,high torque and high Speed transmission system^[1].Therefore,using it to make high-end machine tool spindles,helicopters,and automobile drive shafts is also a trend in recent years.As one of the most important parts of the transmission system,the composite material shaft directly affects the safety of the rotating equipment.Therefore,it is very necessary to master the dynamic characteristics of the composite material shaft.The composite material shaft is different from the ordinary material shaft.It has typical anisotropy,nonlinearity and other characteristics.Therefore,the dynamic balance of the composite material shaft is an important and quite complicated part of its dynamic characteristics research.If the size and distribution of the imbalance of the composite material shaft can be measured by an appropriate dynamic balance algorithm,and then the plane position of the dynamic balance weight can be directly determined,and the appropriate loading strategy can be used to directly add the weight,which will greatly reduce the imbalance The system vibration caused by the fault ensures the efficient and stable operation of the transmission system.This paper mainly focuses on the dynamic characteristics of composite material shaft in the process of dynamic balance,the mechanism of imbalance,the identification method of dynamic balance parameters,etc.The work of the thesis mainly includes the following parts.(1)The finite element analysis model of the composite material shaft was established and revised,and the dynamic characteristics of the composite material shaft were calculated based on this analysis model,and the influence of the fiber layering method of the composite material on its natural frequency was analyzed.First,LMS?SAMCEF and MATLAB software are used to model the composite material shaft dynamics,and the parameters such as the modal shape,natural frequency and critical speed in the dynamic characteristics are calculated.Secondly,the calculated natural frequency is compared with the actual measurement to modify the model,and the genetic optimization algorithm is used to optimize the model to obtain the best dynamic model.Finally,the influence of the fiber layup method of the composite material on its natural frequency is analyzed,which mainly includes the influence of the three factors of fiber winding angle,fiber diameter,and fiber layup sequence on the first three natural frequencies,and the various fiber layup factors are obtained.The law of the influence of a single action and the combined action of various factors on the natural frequency.(2)Trace the origin of the initial imbalance of the composite material shaft,quantitatively calculate the imbalance of the flange in the shaft component,qualitatively analyze the synthesis method of the composite material shaft imbalance,and study the size and distribution of the random imbalance on the vibration of the composite material shaft system The impact mechanism of the response.First,the initial unbalance of the composite material shaft component is analyzed,and the influence formula between the manufacturing tolerance of the flange and the amplitude of the unbalance is deduced.Secondly,the source of composite material shaft imbalance is analyzed,and the vector superposition formula of composite material shaft imbalance is derived from the perspective of probability and statistics.The LMS?SAMCEF software was used to analyze the influence of the size and distribution of the unbalance on the unbalanced response and dynamic balance of the shaft.The study found that the distribution and amplitude of the unbalance have a greater impact on the unbalanced response of the composite shaft.Among them,the distribution of the unbalanced quantity has a greater impact on it,which has a greater guiding significance for the dynamic balancing operation of the composite material shaft.Finally,based on the Monte Carlo idea,a numerical simulation of the random unbalanced response of the system caused by the randomly distributed unbalanced quantity is carried out,and the fluctuation range of the deflection of each confidence interval of the system under the random unbalanced fault condition is obtained;the Sobol'method is used for different speeds.The sensitivity of the system response at each node is analyzed,and the contribution of the imbalance at different axial positions to the system vibration response is obtained.(3)In view of the poor effect of conventional dynamic balancing methods on composite material shafts,the model-based displacement minimum algorithm and the shaft distribution imbalance estimation algorithm are used to identify the dynamic balance parameters of the shaft.The two dynamic balancing algorithms are extremely effective.The vibration amplitude at the first-order critical speed of the composite material shaft is reduced,so that the maximum deflection of the shaft after balance is kept below 15%of that before balance.Based on the discrete random distribution model of the unbalance of the rotating shaft,the dynamic balance parameters of the composite material rotating shaft are identified by the minimum displacement algorithm,and the axial position of the maximum unbalance discretely distributed on the rotating shaft is accurately identified.On this basis,the influence of measurement error and finite element modeling error on the recognition accuracy of the algorithm is analyzed,and the conclusion that the algorithm is more sensitive to measurement errors is drawn.In view of this,this paper proposes an orthogonal fusion algorithm based on the same-source information fusion technology,which greatly reduces the sensitivity of the minimum displacement algorithm to measurement errors.Based on this improved algorithm,the influence of the combination method of sensor measurement position on the recognition accuracy is studied,and optimization algorithms such as fruit fly algorithm,particle swarm algorithm,genetic algorithm are combined to optimize the amplitude and phase of imbalance,and the final calculation is obtained.The position of the balance surface,the phase and size of the loading mass in the dynamic balancing operation are analyzed,and the calculated data is used to dynamically balance the rotating shaft.According to the research of the paper,the minimum displacement algorithm has a good matching degree with the Drosophila optimization algorithm,and its recognition accuracy,optimization efficiency,and dynamic balance effect are higher than other optimization algorithms.Based on the continuous random distribution model of the unbalance of the rotating shaft,the relationship between the mass distribution function of the unbalance and the unbalanced response of the rotating shaft node is established by using the unbalance estimation algorithm of the rotating shaft and the finite element program of the rotating shaft.Use n-degree polynomial curve to fit the mass eccentricity curve on the horizontal and vertical planes,derive the coefficient conversion matrix of the 3rd and 4th degree polynomial fitting curve,and use the 3rd and 4th degree polynomial curve to fit the mass eccentric curve of the shaft respectively.The influence of the model error on the recognition accuracy is discussed.On this basis,this paper proposes a mass addition strategy for equalizing the shaft segment and a mass addition strategy for equalizing the unbalanced amount,and uses two mass addition strategies to dynamically balance the shaft.operating.According to the research of the paper,the fusion effect of the mass addition strategy of equal division imbalance quantity and the distribution imbalance estimation algorithm is better,and its dynamic balance effect is better than the mass addition strategy of equal division shaft segment.