A Frequency Modulation GMI Magnetic Sensor Base on Inverter Multivibrator with Longitudinal Excitation

Frequency Modulation (FM) GMI Magnetic Sensors has excellent performance in high signal-to-noise ratio and low power consumption. In this article, the FM magnetic sensors with longitudinal excitation are presented. The inductance of the sensing head versus the excitation frequency and the external magnetic field is tested by the impedance analyzer. The results show that the inductance is sensitive with the excitation frequency from 200kHz to 600kHz. The bias magnetic field generated by a permanent magnet is used to make the sensing head working at a linear region with the highest sensitivity. Three kinds of magnetic sensors with different inverter multivibrators circuits are illustrated and their static characteristics are provided through calibration experiments and data analysis. It shows that the first type has the highest sensitivity (41.0kHz/Oe) and the third type has the best linearity.

Micro Hole Elliptical Supersonic Boring Quality Research

In this paper a method of ultrasonic elliptical vibration cutting has been applied to precision boring of micro hole due to its superior performances such as low cutting force, high quality surface finish and long tool life. A transducer with the longitudinal excitation is carried out to machining(boring) micro hole of 1Cr18Ni9Ti workpiece. The cutting force and surface quality are studied in detail.The workpiece with surface roughness of Rz 0.4μm is achieved.The results showed that the ultrasonic elliptical vibration transducer can be applied rationally in micro hole precision boring.

Coupled longitudinal and transverse vibration of automotive belts under longitudinal excitations using analog equation method

There are many studies on vibrations of moving belts originated from automotive belt drives. These studies, however, mainly consider the nonlinear effect of the transversal vibration of the belt under transversal excitation without considering the coupling effect between the transversal and longitudinal vibrations under longitudinal excitation. In this paper, a nonlinear model is built for a standing tensioned belt periodically excited longitudinally at one end with a known amplitude and frequency and with the other end clamped, which allows for coupling between the periodic longitudinal excitation and transversal vibration. The nonlinear system is solved using the Analog Equation Method. The two coupled nonlinear hyperbolic differential equations of the system are reduced to two uncoupled linear equations pertaining to the longitudinal and transverse deformation of a substitute beam with unit longitudinal and bending stiffness, respectively. The reduced equations are under a fictitious time-dependent load distribution with the same boundary and initial conditions. The fictitious forces are established numerically from the integral expression of the oscillation solution with the requirement that the equations of motion be satisfied at discreet time intervals. It is found that the transversal vibration appears as a stable and predictable beating phenomenon due to an internal resonance from the periodic energy transfer between the longitudinal excitation and the transversal vibration, which manifests itself as a standing wave.