Analysis Of Multiphysics Coupling And Temperature Control For Giant Magnetostrictive Transducer

As a new type of intelligent material with superior performance,giant magnetostrictive material(GMM)has broad application prospects.The giant magnetostrictive transducer using GMM has unique advantages in precision machining and ultrasonic device.In practical applications,especially in high-frequency operation,the loss of the GMM and the heating of the coil cause a serious temperature rise of the giant magnetostrictive transducer,and the increase in temperature will restrict the application of the transducer.Based on the understanding of the influence of temperature on the giant magnetostrictive transducer,this thesis takes a structural treatment on GMM to reduce eddy current loss and an efficient cooling to control the temperature caused by the loss.At the same time,the analysis of eddy current loss,analysis of multiphysics coupling and studies of temperature control for giant magnetostrictive transducer are finished.The main work of this thesis includes following aspects:1)According to the working principle and characteristics of the giant magnetostrictive transducer,the overall structure of the transducer is designed: The driving component is selected.The GMM is sliced and hollowed out to reduce the eddy current loss.At the same time,the geometry of the excitation coil and the magnetic field loop are designed accordingly.In order to avoid the tensile stress of the GMM,the pre-pressure mechanism is designed.A heat pipe radiator is designed to cool the transducer directly and efficiently.2)Establish GMM multiphysics coupled magnetostrictive strain model based on thermodynamic principles;Analysis of eddy current loss for GMM is carried out,and the model of eddy current loss for different structures is established.The effectiveness of eddy current suppression by hollow stack structure is verified by comparison.The eddy current loss model and magnetostrictive strain model based on hollow stack structure are used to establish GMM multiphysics coupled hysteresis nonlinear model.The model is numerically simulated and 1000 Hz GMM hysteresis loop is obtained.Based on the established multiphysics coupled hysteresis nonlinear model and strain model,a multiphysics coupled hysteresis nonlinear dynamic model of the transducer is built to describe the dynamic characteristics.3)Through the calculation of the hysteresis curve,the loss power of the GMM is obtained.Based on the temperature rise,analyze the effect of temperature on GMM hysteresis curve,magnetostrictive strain,overall strain and output displacement.For the temperature control requirements of transducers,the design,calculation and simulation analysis of the heat pipe radiator are finished.The heat pipe length,fin outer radius,fin thickness,number of fins and air cooling degree of the heat pipe radiator are optimized.4)The hysteresis curve measurement experiment of GMM is carried out.The experimental results of 1000 Hz GMM hysteresis loop have good fitting effect with the numerical simulation results of the hysteresis nonlinear model established in this thesis,which proves the validity of the model.Meanwhile the variation of the shape,area and loss power of hysteresis curve under different frequency and bias magnetic field conditions are analyzed.The dynamic characteristics of transducer are measured experimentally to analyze the output characteristics of the transducer under different frequency and bias magnetic field conditions.The temperature control experiment of the heat pipe radiator is conducted on the transducer.Under the cooling,the transducer can be controlled to room temperature.The research results of this research provide new methods and ideas with reducing the eddy current loss of GMM,establishing a giant magnetostrictive transducer model and controlling its temperature rise.It has important engineering value for the high frequency application of transducers.