Chris Snook

Drop Weight Impact Test Fracture of Vinyl Ester Composites: Micrographs of Pilot Study

The shrinkage of vinyl ester particulate composites has been reduced by curing the resins under microwave conditions. The reduction in the shrinkage of the resins by microwaves will enable the manufacture of large vinyl ester composite items possible [12-15]. This project is to investigate the difference in impact strength between microwave cured vinyl ester particulate composites and those cured under ambient conditions. Drop weight impact test will be used to achieve the aim of the project [7]. The results show that the difference in the impact strength is minimal [5]. The original contribution of this paper is to view the fractured surface of composites cured under different conditions to find out whether they are the same. If they are the same, it can be deduced that the initial expansion of the composite due to microwave irradiation will not affect the final structure of the composite.

Detection of Potentially Explosive Methane Levels Using a Solid-State Infrared Source

Detection of methane gas which may be approaching the concentration limit when explosive ignition could occur is an important industrial problem. Optical methods for gas detection are attractive, and near-infrared (IR) wavelengths are especially suited to the detection of hydrocarbon gases. Unfortunately, temperature-related drift of solid-state IR sources is problematic. A method for stabilizing the response of a near-IR solid-state gas detection system operating at 2350 nm is presented in this paper. The system employs a broadband LED source and a wideband photodetector. Because IR absorption in the gas cell is used as an indirect measure of gas concentration, it is necessary to stabilize the optical source power. We approach this problem by employing a novel two-frequency pulsed excitation method. Stable measurements suitable for detecting the presence of methane gas at a concentration of 50% of the lower explosive limit are experimentally demonstrated. The response of the system is validated against the HITRAN IR spectroscopy database, by incorporating the emitter and detector IR profiles. Good agreement between the derived gas concentration and theoretical predictions based on standard gas absorption models is demonstrated for 2.5% methane in air, which is a critical point for determining the presence of potentially explosive mixtures.

Fracture Toughness of Vinyl Ester Composites Cured by Microwave Irradiation: Preliminary Results

The shrinkage of vinyl ester particulate composites has been reduced by curing the resins under microwave conditions. The reduction in the shrinkage of the resins by microwaves will make the manufacture of large vinyl ester composite items possible. The impact strength of the vinyl ester composite components cured under microwave was reduced only by 1% when tested by drop weight impact tests. The aim of this study is to investigate the difference in fracture toughness between microwave-cured vinyl ester particulate composites and those cured under ambient conditions. Short bar method of fracture toughness measurement was used to perform the tests. The results show that the difference in the fracture toughness is minimal between the ambient condition-cured and the microwave-cured samples, provided the power level and duration of microwave irradiation are properly and optimally selected.

Impact strength of vinyl ester composites cured by microwave irradiation: preliminary results

Abstract The shrinkage of vinyl ester particulate composites has been reduced by curing the resins under microwave conditions. The reduction in the shrinkage of the resins by microwaves will enable the manufacture of large vinyl ester composite items possible. This project is to investigate the difference in impact strength between microwave cured vinyl ester particulate composites and those cured under ambient conditions. Drop weight impact tests will be used to achieve the aim of the project. The results show that the difference in the impact strength is minimal.

Micrographs of the Fracture of Vinyl Ester Composites Cured by Microwaves: Pilot Study

Short bar method of fracture toughness measurement was used to perform tests to find out the difference in fracture toughness between microwave cured vinyl ester particulate composites and those cured under ambient conditions [1–3]. The results show that the difference in the fracture toughness is minimal [5]. This paper presents the analysis of the fracture of the samples using a Scanning Electron Microscope (SEM). The fracture toughness of vinyl ester composites varies slightly after undergoing microwave treatment; it varies with different microwave power level and duration of exposure. The microscopic results show some important features such as brittle behavior, elongation of the fracture surface. The sample with lower fracture toughness is found to have more bubbles in the composite than those samples with higher fracture toughness. Therefore, the microwave power level and exposure time appear to correlate with the fracture toughness values obtained.

Short Bar Tests for Vinyl Ester Particulate Reinforced Composites Cured by Microwaves

Abstract This paper examines some of the drivers and barriers to the development of green commercial buildings in Australia based on a series of interviews with key stakeholders in the building industry. The business drivers for building green are described along with some of the barriers including perceived fi nancial risks such as split incentives, initial capital costs and lack of life cycle costing, perceived construction risks including project delivery mechanisms, material procurement and site practices and the current regulatory environment. Finally an agenda for the future with recommendations such as the need to establish integrated design teams at the conceptual design stage and to undertake post-occupancy studies of completed buildings to assist in the development of green commercial buildings are presented

A zero-cost, real-time, Windows signal laboratory

This paper introduces a Windows-based signal capture, display, and waveform synthesis package called ‘Win-eLab’. The software is able to run on a conventional desktop or laptop with no additional hardware, and can perform real-time Fourier analysis on audio-frequency signals. This paper is intended as an introduction to Win-eLab, aimed at motivating further use of it in both teaching and self-directed learning contexts. The use of the software to familiarize students with the concept of ‘laboratory’ instrumentation is discussed, as well as the usefulness of a simultaneous time-domain/frequency-domain display for understanding signals, particularly in signal processing and communications systems courses. It is anticipated that applications may extend beyond electrical and electronic engineering – for example, as an aid to understanding mechanical vibrations, acoustics, and in other discipline areas.

Micrographs of Fractured Vinyl Ester Composites

This paper reports the difference in impact strength between microwave cured vinyl ester particulate composites and those cured under ambient conditions, by examining the micrographs of the fractured specimens. The drop weight impact test had been used to fracture the samples. The original contribution of this paper is to tell the fracture behavior of the samples as well as the relative toughness of the specimens by viewing their micrographs. The results show that the difference in the impact strength between optimally (lower power and longer exposure duration) microwave cured samples and those cured under ambient conditions is minimal. However, if the specimens were cured using higher power, the resulting toughness of the samples would be lower as many voids would form in the samples due to the initial expansion of the composite.