Research And Realization Of Low-frequency Mechanical Spectrometer With High-precision And Large-amplitude

The low-frequency mechanical spectrometer is a significant apparatus aming to research the internal friction of solid materials.This paper describes and designs a new low-frequency mechanical spectrometer with high-precision and large-amplitude based on the fundamental of Ge’s torsional pendulum and mechanical structure of TPA-8 low-frequency mechanical spectrometer.The main contents of this paper are as follows:(1)This paper provides an overview and information about the basic concepts of internal friction,the measurement principle and the mechanical structure of low-frequency mechanical spectrometer under the mode of forced vibration.The vertical image of sample analyse mechanism and vertical image of pendulum analyse mechanism,which were designed to adjust the posture of sample and vertical pendulum,focus on improving the system precision of Low-frequency mechanical spectrometer.(2)Establishing low-frequency mechanical spectrometer model.The parts were manufactured by the design drawings,assembled and installed with the help of level instrument.The Helmholtz coil drive circuit is modularized designed in order to expand the sinusoidal drive signal voltage range depending on the actual demand.Afterwards,the strain amplitude range of low-frequency mechanical spectrometer has been broadened.(3)Labview and Matlab were used to design human-computer interaction interface.Labview is used to control the data acquisition card and each driver module to transfer,collect and preserve data which is filtered by the median and Butterworth filter.Besides,the phase difference of the collected data is caculated with all-phase FFT algorithm in Matlab.At last,the internal friction curve was drown with the change of collection times.(4)The sample test part model of low-frequency mechanical spectrometer is built up.The relationship between the displacement of a laser end and the maximum stress to the specimen is determined through the finite element analysis.Then,according to above results,the limitation of laser displacement is find out.Meanwhile,the relationship between strain and sinusoidal drive signal voltage amplitude within the deflection limitation is analized.Finally,the strain-internal friction curve by processing data is obtained with Origin.The sample vertical image analysis mechanism and vertical pendulum image analysis mechanism is adopted to solve the deviation problems which is a larger angle of clamping during the samples clamping operation.Besides,posture fine-tuning structures is applied which limits the enlargement of error cone and improves the system accuracy.The large strain amplitude of the instrument helps to show a significant change in the internal friction of the specimen by comparing the system in this paper with the TPA-8 low-frequency mechanical spectrometer with same size samples.Meanwhile,Labview and Matlab were used to design human-computer interaction interface helps to improve the real-time and scalability of the system.The maintenance difficulty of this system is reduced by applying the modular design in Hardware structure.