Experimental study of hysteresis in piezoactuator & design review and fabrication of piezoactuator forging machine

• Main Author: Lin, Rongkai.
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Final Year Project
• Language: English
• Published: 2012
• Subjects: DRNTU::Engineering::Mechanical engineering::Mechatronics
• Online Access: http://hdl.handle.net/10356/49373
• Institution: Nanyang Technological University

The use of micro-forming machine can be seen as an advantageous manufacturing process compared to conventional micro-machining techniques and lithography in terms of high volume production and minimal material wastage. However, the methods used for fabrication were based on macro scale forming concept that does not include grain size effect. Thus a forging machine with ultra-high stiffness and an actuator with precision displacement controlled with high loading capacity were required to be design and build for a investigative experiment of size and thermal effect on the mechanical properties of micro-formed parts. Piezo-electric actuator was chosen as the choice of actuator due to the high accuracy of displacement of up to 10nm, repeatability and ability to deliver a force of up to 16KN within a small area. However, the actuator performance was affected by hysteresis which is defined as a non-linear loop like response of the actuator. An investigative study was conducted to evaluate various parameters such as frequency, amplitude and mass inertia effect that would affect the hysteresis curve of the actuator. A mathematical model could only be use to model hysteresis curve of a given parameter only if the hysteresis curve of the actuator remains unchanged. This model would be used to develop a proportional–integral–derivative (PID) controller to compensate the hysteresis response of the actuator, converting the non-linear response to a controllable linear response actuating system. Result of experiment 1 has shown the hysteresis curve of the actuator remains relatively constant for an operating frequency between 1-10hz at no load condition. The results of experiment 1 also shown that a varying the amplitude of the actuator at constant frequency alters the aspect ratio of the hysteresis curve, thereby having a non-constant hysteresis. The 2nd experiment findings has shown that mass inertia effect has minimal effect on the hysteresis curve of the actuator at low load while the 3rd experiment only showed the square effect of mass inertial effect with respect to frequency at low frequency and inertia mass range. The 2nd part of the project was to evaluate the design of the forging machine and improved the existing design in terms of ease of manufacturing, assembly and as well as cost reduction. The 3D design was converted into engineering drawing and fabricated accordingly with the use of CNC processes. The parts were delivered, check and assembled accordingly with the piezoactuator installed and electrically isolated.