Advanced Materials Research Vol. 633

Abstract: Today additive manufacturing is shaping the future of global manufacturing and is influencing the design and manufacturability of tomorrows products. With selective laser melting (SLM), parts can be built directly from computer models or from measurements of existing components to be re-engineered, and therefore bypass traditional manufacturing processes such as cutting, milling and grinding. Benefits include: 1) new designs not possible using conventional subtractive technology, 2) dramatic savings in time, materials, wastage, energy and other costs in producing new components, 3) significant reductions in environmental impact, and 4) faster time to market. SLM builds up finished components from raw material powders layer by layer through laser melting. SLM removes many of the shape restrictions that limit design with traditional manufacturing methods, thereby allowing computationally optimised, high performance structures to be utilised. Functional engineering prototypes and actual components can then be built in their final shape with minimal material wastage. Samples and small product runs can be produced quickly at comparatively low cost to test and build market acceptance without major investment. In this chapter we present and discuss some of the concepts and findings involved in the design, manufacture and examination of high-value aerospace components from Ti-6Al-4V alloy produced at the RMITs Advanced Manufacturing Precinct.

Abstract: Support material is often utilised in additive manufacture to enable geometries that are not otherwise self-supporting. Despite the associated opportunities for innovation, the use of support material also introduces a series of limitations: additional material cost, cost of removal of support material, potential contamination of biocompatible materials, and entrapment of support material within cellular structures. This work presents a strategy for minimising the use of support material by comparing the geometric limits of an additive manufacture process to the build angles that exist within a proposed geometry. This method generates a feasibility map of the feasible build orientations for a proposed geometry with a given process. The method is applied to polyhedra that are suitable for close packing to identify space-filling tessellated structures that can be self-supporting. The integrity of an FDM process is quantified, and using the associated feasibility map, self-supporting polyhedra are manufactured. These polyhedra are integrated with non-trivial geometries to achieve a reduction in consumed material of approximately 50%. Nomenclature

Abstract: The level of protective material performance attributes are well defined and highly regulated, however the attributes related to the thermo physiological comfort of materials are not. In this chapter, the application of new materials to firefighting protective clothing systems used in extreme heat is addressed, with a focus on thermo physiological comfort. The new generation of protective textile materials and their structures are evaluated through use of both objective laboratory testing and mathematical modeling methods. In addition, 3D body imaging technology is utilized to demonstrate a method of assessing the fit of protective garments and its potential impact on the thermal status of the wearer. The proposed engineering approach could be used in other areas where the balance between clothing performance and wear comfort is critical, e.g. sport, work wear etc.

Abstract: The digital image correlation method was used in this study to investigate heat polymerizable acrylic resin, which is the material of choice for prosthesis in edentulous patients. The aim was to analyze and determine the force-induced displacement and strain of a complete denture in the physiological force field of edentulous patients. An acrylic lower complete denture was made for the edentulous mandible, placed on the residual ridge of the macerated mandible bone, lacquered with spray, and exposed to a force of 300 N. The Digital Image Correlation system (DIC) (GOM, Braunschweig, Germany) was used to measure the strain in the complete denture, consisting of two digital cameras and the software ARAMIS (6.2.0, Braunschweig, Germany). Both fields indicated the maximum dimensional changes occurred just below the point of force incidence. The displacement field registered movements in the range from 0.165 to 0.782 mm and the principal strain field showed strain values between 1.25 and 18.94%. In vitro investigation of the dynamic behavior of the lower complete denture under load by using the optical measuring system-DIC demonstrated that the strain/displacement alterations were generally influenced by prosthesis movement toward the residual alveolar ridge.

Abstract: Energy efficiency is a key issue worldwide, and not confined solely to the realm of engineers. Past failures of mechanical power system components must be examined carefully in order to minimise future occurrences and increase energy efficiencies. Improved design procedures have been highly sought by engineers and researchers over the past few decades. The latest verified method with strong application potential within the power industry is that of the Theory of Critical Distances (TCD). TCD is not one method, but a group of methods that have a common feature; the use of a characteristic material length parameter, the critical distance L, for calculating the influence of notch-like stress raisers under static and fatigue loading. A case study from a hydro power plant turbine shaft was chosen to illustrate the development of this methodology. The paper illustrates the application of TCD to the fatigue life assessment of a turbine shaft with stress concentrations due to pitting corrosion.

Abstract: Crossed helical gears are used in cars and many household appliances. The trend towards increased comfort in motor vehicles has led to the utilization of more than a hundred servo-drives in luxury class automobiles. Key advantages of crossed helical gears are their simple and inexpensive design, good noise performance and high ratios that can be realized in one step. Sintered steel is a highly favorable material for wheels in crossed helical gears. They are able to satisfy high performance demands in the areas of wear, fretting, tooth fracture and pitting load capacity. This report describes the results of an examination into the use of the iron-based sintered material Fe1.5Cr0.2Mo with pyrohydrolysis in crossed helical gears, in the areas of wear resistance and other damage types under different speeds and loading conditions.

Abstract: Magnetic Force Microscopy (MFM) and Opto-Magnetic Spectroscopy (OMS) were used to characterize HTCV stainless steel and aluminum. Both materials were immersed in 1.0M HCl and 1.0M CH₃COOH solutions for two hours. From the OMS method it was discovered that treated materials showed differences in peak wavelengths. Topographical and magnetic features for steel plate samples showed better resistance to an aggressive medium compared to aluminum. The results and analysis of these investigations are compared and presented in this paper.

Abstract: Since their discovery in 1985, fullerenes have attracted considerable attention. Their unique carbon cage structure provides numerous opportunities for functionalization, giving this nanomaterial great potential for applications in the field of medicine. Analysis of the chemical, physical, and biological properties of fullerenes and their derivatives showed promising results. In this study, functionalized fullerene based nanomaterials were characterized using near infrared spectroscopy, and a novel method - Aquaphotomics. These nanomaterials were then used for engineering a new skin cream formula for their application in cosmetics and medicine. In this paper, results of nanocream effects on the skin (using near infrared spectroscopy and aquaphotomics), and existing results of biocompatibility and cytotoxicity of fullerene base nanomaterials, are presented.

Abstract: Contact lenses are a common optical aid to provide help with refractive anomalies of the human eye. Construction of contact lenses is a complex engineering task as it requires knowledge of optics, materials science, production and characterization methods for product quality. Besides correcting refractive anomalies, by using contact lenses it is possible to change the characteristics of light through the manipulation of material structure properties. Nanomaterials, such as fullerene C₆₀, are candidates for the medium that interacts with light, thus changing its properties. During material syntheses for contact lenses, fullerenes are added to the base material and optical characteristics of the new nanophotonic material are compared with the base material. The engineering, manufacture and characterization of both a commercial and a new nanophotonic contact lens is presented in this paper. The interaction of water with both base and nanophotonic contact lens materials is described. Using experimental techniques, the phenomena of an exclusion zone (EZ) is also identified.

Abstract: The following study was conducted in order to evaluate the effects of height, width and design variations on the stress distribution of vertically loaded, cylindrical titanium implants using finite element analysis (FEA). Three groups of cylindrical titanium TPS surface implants (Premium, Sweden & Martina, Italy) inserted into mandible segments were analysed. The three Premium implants in the first group were of different length (10.0, 11.5 and 13.0 mm) but possessed the same diameter of 3.80 mm. The second group consisted of three Premium implants with the same length of 11.5 mm but with different diameters (3.30, 3.80 and 4.25 mm). In the last group two different implant designs were compared, one featuring platform switching and a straight emergence profile and the other without platform switching. Overall, eight implant-bone samples were analyzed and the resulting stress distributions during vertical loading were obtained. For all eight samples, maximum stress values were found in the area of the implant neck and the stress values decreased in the apical direction. The higher stress values in the second group were detected in the implant with smaller diameter. It was noted that the implant with platform switching experienced lower stresses than the one without platform switching. Changes in length did not have any significant effect on the stress distribution. Under a vertical occlusal load, an implant with a larger diameter and with platform switching had the most favorable stress distribution throughout the implant structure and the adjacent bone tissue.