Dynamic Force Identification Technique Based On The Regularization Method And Application

Determination of the dynamic forces applying on the system plays an important role in the dynamic design, fault diagnosis, system parameter identification and vibration control. In addition, in the ship domain, the force exciting on the propeller is one of the most important parameters in the naval vessels design and test. How to obtain the force is becoming a key problem. In these circumstances, the research of the dynamic load identification technique is very necessary.This paper presents the force identification techniques about impact load, the periodic load and random load. In order to deal with the ill posedness in the force identification process, the regularization method is used. In addition, the force identification technique is applied to identify the propeller vertical thrust in the paper, and the identified results are discussed. The main research work is summarized as follows:1、The identification Technology for the state space force is proposed, and the identification models for the periodic load and random load are unified as an identification model. According to the ill posedness in the process of force identification, regularization technique is used, and comparison of the performance of the criteria for determining the regularization parameter is made in the numerical testing. Then, experiment is made, longitudinal excitation force of the propeller-shafting-boat coupling system is identified in the air.2、In this paper, we extend the force identification technique to identify the propeller longitudinal thrust of the ship. and the actual propeller vertical thrust is identified, the identified results are discussed in the paper. In the numerical simulation testing, the some problems for identification process of propeller longitudinal thrust are studied.3、In the practice, the data for forming the structural matrix of the force identification is usually not measured, the finite element model is a useful method to deal with this problem. However, the finite element model is inaccurate with the real model. In order to update the finite element model, the optimization technique is used in the paper. In the numerical experiment, the propeller-shafting system is used as object of study to updating. At last, an experiment of the stainless steel beam is carried out, and the reliability is verified.4、According to the convolution relationship between the impact load and responses. The paper discrete the convolution, and constructs an impact load identification model in the time domain. In order to deal with the ill posedness of the inverse process, the paper gives an improved regularization operator to overcome this problem. The effectiveness of this method is verified by the numerical test and experiment, and comparison the identified results between the improved and traditional regularization techniques are made.5、A force identification technique of the nonlinear system is presented in the frequency domain. Because the nonlinear system parameters are unknown in the process of identification, the subspace identification technique is used to determine these parameters. To verify the validity of the technique, the single and multiple degrees of freedom nonlinear system is considered in the paper.In the end, the works of this paper are summarized, and the further studies are pointed out.