Aaron S. Blicblau

Applications of fixed and variable frequency microwave (VFM) facilities in polymeric materials processing and joining

Microwave processing of materials is a relatively new technology advancement alternative that provides new approaches for enhancing material properties as well as economic advantages through energy savings and accelerated product development. Factors that hinder the use of microwaves in materials processing are declining, so that prospect for the development of this technology seem to be very promising [Ceram. Bull. 68 (2) (1989) 376]. The two mechanisms of orientation polarisation and interfacial space charge polarisation, together with DC conductivity, form the basis of high frequency heating. Clearly, advantages in utilising microwave technologies for processing materials include penetrating radiation, controlled electric field distribution and selective and volumetric heating. However, the most commonly used facilities for microwave processing materials are of fixed frequency, e.g. 2.45 GHz. This paper presents a state-of-the-art review of microwave technologies, processing methods and industrial applications, using variable frequency microwave (VFM) facilities. This is a new alternative for microwave processing. The technique is geared towards advanced materials processing and chemical synthesis. It offers rapid, uniform and selective heating over a large volume at a high energy coupling efficiency. This is accomplished using a preselected bandwidth sweeping around a central frequency employing frequency agile sources such as travelling wave tubes as the microwave power amplifier. Selective heating of complex samples and industrial scale-up are now viable. During VFM processing, a given frequency of microwaves would only be launched for less than 1 ms.

Fostering Creativity through Engineering Projects.

Summary Final year projects are a showcase for engineering students’ creativity. All final year engineering students at Swinburne University of Technology are required to spend part of their final semester of studies developing and completing various aspects of a major project. The theme of the project work is defined either by industrial sponsors or academic supervisors or by both. In addition, project guidelines are provided by the university for the final submission and completion of the work. The project may be any combination of research, design or developmental work. Within the constraints required by these factors, students’ creativity in their approach and execution of the project work may be both limited and expanded to simulate conditions experienced in a work environment. The culmination of the project work is in a written, oral and visual presentation to a professional audience. It is the students’ own creativity which determines not only the format of all three forms of presentations, but als...

Beyond traditional literacy: Learning and transformative practices using ICT

Educators, government bodies and employers have acknowledged the need for modern learners to acquire 21st century skills using information and communication technologies, to personalise student learning. Students need broader skills than the 3Rs (reading, writing and arithmetic) to operate in the 21st century. These broader skills known as the 4Cs include: creativity, communication, collaboration and critical thinking. The use of information and communication technologies is crucial in developing the 4Cs in conjunction with understanding how learning takes place. However, simply using technology does not guarantee that deep learning will occur. The use of technology needs to align and adapt with our knowledge of learning to be able to operate in a transformative space. This paper is designed to link the understandings of deep learning, 21st century skills and appropriate use of information and communication technologies to provide direction to educators who wish to lead in a technological environment of change.

Effect of rapid curing doped epoxy adhesive between two polycarbonate substrates on the bond tensile strength

Abstract The aim of this work was to determine the bond tensile strength of a polycarbonate sandwich joined with a fast cured epoxy adhesive. A 6.5 kW single mode microwave unit operating at 2.5 GHz was used to fast cure the epoxy adhesive. The samples of polycarbonate were prepared in accordance with ASTM D2095-72 (modified) and glued with a two-part epoxy adhesive mix employing a doping agent for rapid cure in the microwave unit. Two operational parameters, cure time, microwave power and one processing parameter, dopant concentration, were varied to determine their effect on the resulting bond strength. These rapidly-cured samples were then tensile tested to determine the joint strength as a function of the operational and processing parameters. The fracture surfaces of the adhesively joined polycarbonate samples were examined using light microscopy and scanning electron microscopy. A polariscope was employed to determine the variation in stress in the adhesive joint. Conventional curing of epoxy adhesive polycarbonate sandwiches was also undertaken. The tensile strength of these conventionally-cured bonded samples were then compared to that of fast cure using microwave. Results of the processing and testing program indicate the effect of dopant concentration, curing time and microwave absorbed power on the resulting mechanical strength of the adhesively bonded joint.

Online delivery management for teaching and learning

The learning initiative described in this paper looks at how the adoption of a flexible, online learning approach can be used to optimize teaching and learning in engineering materials to a variety of engineering disciplines. The main driver for adopting this approach was to increase the effectiveness of delivery of subject matter. Practical examples are given of delivery strategies, activities and assessment protocols. This flexible, online approach required the development and implementation a learning management system for the provision of online lectures, audiovisual material, discovery-based learning activities and communication tools for the guidance of students in the self-management of their personal learning styles. The implementation of such an online initiative led to an encouraging response from both students and staff. This was seen as pivotal in its contribution to the success of the overall learning strategy.The learning initiative described in this paper looks at how the adoption of a flexible, online learning approach can be used to optimize teaching and learning in engineering materials to a variety of engineering disciplines. The main driver for adopting this approach was to increase the effectiveness of delivery of subject matter. Practical examples are given of delivery strategies, activities and assessment protocols. This flexible, online approach required the development and implementation a learning management system for the provision of online lectures, audiovisual material, discovery-based learning activities and communication tools for the guidance of students in the self-management of their personal learning styles. The implementation of such an online initiative led to an encouraging response from both students and staff. This was seen as pivotal in its contribution to the success of the overall learning strategy.

Comparative study of two materials for dynamic hip screw during fall and gait loading: titanium alloy and stainless steel

BackgroundInternal fixation with dynamic hip screw is a choice of treatment for hip fractures to stabilize a femoral fracture. Choosing the proper implant and its material has a great effect on the healing process and failure prevention. The purpose of this analysis was to assess biomechanical behavior of dynamic hip screw with two different materials implanted in the femur during fall and gait.MethodsA 3D finite element model of an intact femur and a 3D implant within the same femur were developed. A finite element analysis was carried out to establish the effect of load conditions and implant material properties on biomechanical behavior of the dynamic hip screw after internal fixation. Two load configurations are chosen: one simulating the stance phase of the normal gait cycle, and the other replicating a low-energy fall. The implanted femur was investigated with two different materials for the dynamic hip screw: stainless steel and titanium alloy.ResultsDuring stance, more stress is placed on the implanted femur compared with the intact femur. During a fall, the implanted femur is in a greater state of stress, which mostly occurs inside the dynamic hip screw. Titanium alloy decreases stress levels by an average of 40% compared with stainless steel. However, deformation is slightly reduced with a stainless steel dynamic hip screw during both load cases.ConclusionsAfter internal fixation, dynamic hip screw generates greater stresses within the implanted femur compared with the intact femur under the same loading conditions. A titanium alloy implant appears to undergo less stress from a low-energy fall compared with stainless steel and can be considered the preferred implant material. The critical parts of the dynamic hip screw are the forth distal screw and the plate.

The Trend Towards Materials in Science and Technology Education

The teaching of science and technology in the final year of high school is examined in a new curriculum developed for the education system in Victoria, Australia. The traditional areas of Physics and Chemistry together with a technology related subject, Materials and Technology, are investigated The major curriculum link amongst these studies was the area of materials. In Chemistry this involved the nature of materials, the chemical basis for the production of metals and polymers, and the social consequences of waste disposal. Within Physics, the major involvement was the investigation of the structure and physical properties of materials through theory and practical investigation. The selection of materials, production of components and their testing were the major area involved with Materials and Technology. Although the area of materials related all three subjects enrollments were comparatively high for Physics and Chemistry but Materials and Technology had less than one tenth as much enrollment. Similarly, school providers were significantly lower for materials and technology. Materials and Technology is still considered a vocational subject compared with the science oriented subjects. When gender enrollments were considered, Chemistry had a similar number of females and males, Physics had twice as many males as females, and Materials and Technology had twice as many males as females. This appears to be a consequence of typical gender roles.

Non-destructive evaluation using variable frequency microwaves

Microwave assisted Non-Destructive Evaluation (NDE) technologies have been utilised in industry for materials characterization and quality assessment. This paper discusses the potential of using broadband variable frequency microwaves (2.5−18 GHZ) for diagnosing materials integrity, especially during processing in resonant cavities. The technique is compared to conventional microwave based NDE. Details regarding system configuration with on-line process control and volumetric quality control capabilities are included for microwave curable epoxy test pieces. The principles of microwave interactions with these materials are explained and experimental findings presented.

Stress analysis of a novice windsurfer sail by finite element analysis

The purpose of this work is to investigate the forces applied, and the resultant material deformations and stresses, on a novice windsurfer sail. Finite Element Analysis (FEA) modelling is applied to both a mast and sail of a specified size. After verification of the modelling process, the results are analysed to identify possible improvements that could be made to the sail to enhance longevity. The emphasis is on material characteristics and their performance under given loading conditions. A detailed description of the modelling work is given, and is followed by an analysis of the sail deflection and stress results obtained.

Rapid determination of the optimum frequency band and temperature profile using fully computerised VFM oven

Abstract Recent developments in variable frequency microwave (VFM) ovens in the market for both laboratory scale application and industrial use for materials processing has led to a new way of thinking for better determination of materials–microwave interactions. This paper reports the use of a VFM oven to determine rapidly and efficiently the optimum frequency band and temperature profile of some dielectric materials such as thermoplastic polymers. The objective was to accurately describe what is the best frequency band for processing these selected materials and the temperature profiles (time vs temperature) using a four-level cavity characterisation facilitated by a fully computerised VFM oven. A fibre optic sensor was used to determine the temperature profile when samples were heated in the oven. The results of the cavity characterisation and temperature profile were compared and analysed using suitable software. For each material, an optimum frequency which could successfully interact with the samples was found, thus allowing efficient use of microwaves in terms of time and energy. The time the microwave power takes to reach the expected processing temperature, at a certain frequency, was also investigated.