Gerald Byrne

Enhancing polymer adhesion through surface activation using an in-line atmospheric pressure plasma

A reel-to-reel atmospheric pressure plasma treatment system known as Labline?, was used to activate the surface of Polypropylene (PP) and Polyethylene Terephthalate (PET). An epoxy adhesive was used to bond the activated polymers and the bond strength was assessed using the tensile lap shear test method. For PP treated in a helium discharge at 900 W a fivefold increase in adhesive bond strength was observed compared with that of the untreated polymer. The effect of adding nitrogen and oxygen into the helium plasma was examined, both with respect to the bond strength of the epoxy and polymer surface energy. An 18-fold increase in adhesive strength was observed after the treatment of PP in a helium/oxygen plasma, while a threefold increase was observed for PET. A similar increase in adhesion was observed for PET treated in a helium/nitrogen plasma, while a 16-fold increase in adhesion was obtained for PP.

Electromechanical modelling for piezoelectric flextensional actuators

The piezoelectric flextensional actuator investigated in this paper comprises three pre-stressed piezoceramic lead zirconate titanate (PZT) stacks and an external, flexure-hinged, mechanical amplifier configuration. An electromechanical model is used to relate the electrical and mechanical domains, comprising the PZT stacks and the flexure mechanism, with the dynamic characteristics of the latter represented by a multiple degree-of-freedom dynamic model. The Maxwell resistive capacitive model is used to describe the nonlinear relationship between charge and voltage within the PZT stacks. The actuator model parameters and the electromechanical couplings of the PZT stacks, which describe the energy transfer between the electrical and mechanical domains, are experimentally identified without disassembling the embedded piezoceramic stacks. To verify the electromechanical model, displacement and frequency experiments are performed. There was good agreement between modelled and experimental results, with less than 1.5% displacement error. This work outlines a general process by which other pre-stressed piezoelectric flextensional actuators can be characterized, modelled and identified in a non-destructive way.

Modelling of Piezoelectric Actuator (PEA) for Advanced Process Control in Chemical Mechanical Polishing (CMP)

Lead zirconate titanate (PZT) stacks are commonly used for submicron resolution actuation, fast response times and high sensitivity. They are usually modeled as expansion generators without external load. This paper proposes an electromechanical model for a commercially available micro-piezoelectric actuator (PEA) which comprises pre-stressed PZT stacks and external amplifier flexure frame for closed loop force control. The proposed model avoids the need to measure the piezoelectric charge which is usually required in conventional electromechanical models. The mechanical part of the PEA was modeled as a linear, lumped, double mass-spring-damper system and the related parameters were experimentally identified. The PEA system was characterised under load-free and load-applied conditions, and the electromechanical coupling ratios which describe the energy transfer from the electrical domain (voltage) to the mechanical domain (endpoint displacement/force) were experimentally determined.

Piezoelectric drive systems in ultraprecision machines: a review of the state-of-the-art

The production of ultraprecision and micromachined components has been enabled by the development of a range of drive system technologies with commensurate resolution. In particular, systems based on piezoelectric actuators have provided an alternative to mechanical drive systems. These actuators have been incorporated in drive systems for high resolution positioning of atomic force microscopes, high frequency vibration compensation and high speed valves for diesel injection. The performance of systems based on piezo actuators is characterised by high electromechanical advantage, submillisecond response times and nanometric resolution. In many cases the inherent limited range of travel has been compensated by the design of flexure systems. When combined, these provide precision control free of friction and backlash, otherwise unattainable with conventional mechanical drives. The objective of this paper is to give an overview of the current state-of-the-art. It will highlight the novel application of these alternative technologies. The advantages of piezoelectric technology and their limitations will be discussed.

Methodology for modeling tidal turbine characteristics

In tidal turbine engineering it is common place to use the theory of wind energy engineering in the modeling of turbines. This paper identifies the common design principles in the field, addresses the pitfalls of adopting this theory, and attempts to identify other modeling techniques that might add to the knowledge base used in preparing power production estimates. A methodology for modeling different turbine designs is postulated.

Optics education within engineering at University College Dublin

Undergraduate students within many of the departments which make up the Faculty of Engineering and Architecture at University College Dublin meet optics, optical inspection techniques and opto-electronics at various times during their standard four year undergraduate degree course. As well as optics fundamentals taught as part of their physics courses, engineering courses specifically concerning optics and opto-electronics are available. Furthermore many graduate students are involved in either projects, which are completely optics based, or carry out research projects involving the use or development of specific optical instruments. These projects include the development of image processing capture and processing software, high power laser machining of materials, design and testing of lasers for fiber optic telecommunication and sensing applications and photochemistry. In this paper we offer a brief review of some of the main optical educational themes covered within our faculty and present some details regarding a few optics based postgraduate research projects.