Research Of Detection Method On Ultrasonic Long Bone Guided Wave Parameters Based On The Time-frequency Transforms

Osteoporosis as a common bone disease has been a serious threat to human health life. Dual-energy X-ray detection method is often used as a standard, but this method ignores the influence of the mechanical properties and bone microstructure effects. Osteoporosis can be diagnosed effectively by the quantitative ultrasound technology, and generally the measurement sites are cancellous bone and long bones. The ultrasonic guided waves detection method of long bones not only has widely measurement site, easy to be accepted, but also contains all the structure and characteristics information of long bone.The main work of this paper is as follows:1. Multimode guided wave signals synthesis.According to the parameters characteristic of the long bones and steel, the transfer function and group delay of guided wave signal is established. By passing the excitation signal through the transfer function of the system, the corresponding multimode guided wave signal.2. AO mode signal fitting.The Hilbert-Huang Transform is used to analysis the steel pipe simulation signal to extract the time and frequency coordinate corresponding to the maximum energy points from the Hilbert spectrum of the intrinsic mode function, and then combined with the thickness parameters to fit the AO mode signal.3. Evaluation of the long bones Poisson's ratio.To get characteristic velocity parameter from the time-frequency figure of the S transforms, the relationship between characteristic velocity and Poisson's ratio and thickness is studied. It is ultimately proved that the characteristic velocity of Al and SO modes signal has a good linear relationship to Poisson's ratio, and little affected by the thickness. It can be used to monitor the changes of Poisson's ratio in the long bones, which contribute to a comprehensive diagnostic evaluation of long bones and bone disease.4. Steel tube guided wave signal analysis experiments.The detection method is used to deal with the steel tube guided wave signal, and the feasibility of the method is validated.The aforementioned work has great significance to the ultrasonic guided wave signal analysis, to provide a new basis for multi-parameter detection of bones, and contributes to the early diagnosis of bone diseases such as osteoporosis.