Two-dimensional lubrication analysis and design optimization of a Scotch Yoke engine linear bearing

Recent study has shown that the application of a Scotch Yoke crank mechanism to a reciprocating internal combustion engine reduces the engine's size and weight and generates sinusoidal piston motion that allows for complete balance of the engine. This paper describes detailed investigation of the performance of a linear bearing assembly, which is one of the key components of the Scotch Yoke mechanism. The investigation starts by solving Reynolds equation for the Scotch Yoke linear bearing. The two-dimensional lubricant flow is numerically simulated and the calculated results are compared with experimental results from a linear bearing test rig. The performance characteristics and a design sensitivity analysis of the bearing are presented. Dynamic testing and analysis of an instrumented linear bearing on a test rig are used to validate the numerical simulation model. The oil supply and lubrication mechanism in the linear bearing are analysed and described in detail. This work aims to provide new insights into Scotch Yoke linear bearing design. In addition, strategies for optimization of the linear bearing are discussed

Capability framework for sustainable manufacturing of sports apparel and footwear

The sporting goods sector is characterized by large volumes of production, high levels of consumption and short product life cycles resulting in high disposal rates and waste. Manufacturing of sports products is distributed globally through tier-based supply chains and complex logistics systems. Companies within such supply chains have different levels of capability in sustainable manufacturing, which impacts on the sustainability of the overall business. Reducing environmental impacts is of particular concern for companies at present, due to heightened requirements for the reduction of energy and water consumption, waste and greenhouse gas (GHG) emissions. This article describes outcomes of a research project conducted in collaboration with a global sporting goods manufacturer that focused on the development of relevant capabilities across their supply chain for sustainable manufacturing of sports apparel and footwear. The article presents the developed sustainable manufacturing framework and capability assessment results obtained for selected companies within the supply chain of this global manufacturer in Asia

Constitutive Modeling of Additive Manufactured Ti-6Al-4V Cyclic Elastoplastic Behaviour

Metal additive manufacturing techniques have been increasingly attracting the interest of the aerospace and biomedical industry. A particular focus has been on high value and complexity parts and components, as there the advantages offered by additive manufacturing are very significant for the design and production organisations. Various additive manufacturing techniques have been tested and utilized over the past years, with laser-based technology being among the preferred solutions – e.g. selective laser melting / sintering (SLM / SLS). Fatigue qualification, as one of the primary design challenges to meet, imposes the need for extensive material testing. Moreover, this need is amplified by the fact that currently there is very limited in-service experience and understanding of the distinct mechanical behaviour of additively manufactured metallic materials. To this end, material modelling can serve as a mediator, nevertheless research particular to additively manufactured metals is also quite limited. This work attempts to identify the cyclic elastoplastic behaviour characteristics of SLM manufactured Ti-6Al-4V. A set of uniaxial stress and strain controlled mechanical tests have been conducted on as-built SLM coupons. Phenomena critical for engineering applications and interrelated to fatigue performance (mean stress relaxation, ratcheting) have been examined under the prism of constitutive modeling. Cyclic plasticity models have been successfully employed to simulate the test results. Moreover, a preliminary analysis has been conducted on the differences observed in the elastoplastic behaviour of SLM and conventionally manufactured Ti-6Al-4V and their possible connection to material performance in the high cycle fatigue regime

Effects of Spin on Tennis Ball Aerodynamics: An Experimental and Computational Study

The aerodynamic behaviour of a tennis ball is very complex and significantly differs from other sports balls due to its surface structures (fuzz, seam orientation etc). Relatively high rotational speeds (spin) make the aerodynamic properties of tennis balls even more complex. Although several studies have been conducted on drag and lift in steady state condition (no spin involved) by the author and others, little or no studies have been conducted on spin effects. The so called Magnus effect on a sphere is well known in fluid mechanics. It is believed that the spinning can affect aerodynamic drag and lift of a tennis ball thus the motion and flight path of the ball. Therefore, the primary objectives of this work are to study the spin effects using both experimental and computational methods. In order to achieve these objectives, a series of tennis balls were used to measure their aerodynamics forces as a function of wind speeds, seam orientation and spins. The experimental study was conducted in the RMIT Industrial Wind Tunnel. A computational study of a simplified tennis ball was also studied using commercial software ‘FLUENT’. The CFD results were compared with the experimental findings. Flow around the ball was visualised with smoke

Prospects for liquefied natural gas and other alternative fuels for future civil air transportation

Fundamental issues related to the possible introduction of liquid methane, propane or butane fuelled civil passenger transport aircraft are addressed. It is proposed that partial transition to one, or a mixture, of these alternative fuels may provide an operational interim option when supplies of Avtur become prohibitively expensive. Preliminary criteria to determine the suitability of alternative fuels are also included

Aerodynamic analysis of Speedo Fastskin-I Swimsuit

Swimming is one of the most energy intensive sporting events, where a winner is decided by a short margin. The winning time margin can be increased by various means, including engineered outfits within the game's regulations. In swimming, apart from optimisation of the swimmer's body, an appropriately devised swimsuit can play a significant role in reducing the drag, thereby enhancing the winning time margin. The main motivation for undertaking this study stems from the increasing levels of technical sophistication in the swimsuits that are claimed by the manufacturers for performance enhancement. Therefore, the goal of this paper is to undertake an experimental study with microscopic illustration of the swimsuit fabric, and its effects on aerodynamic properties. The study utilised a commercial swimsuit under stretched and un-stretched conditions of fabric morphology, and their impact on aerodynamic drag. This study was conducted using a wind tunnel for a range of Reynolds numbers. The simplified body shape was used to determine the aerodynamic drag. The finding of this study illustrates that there is a significant difference between the aerodynamic drag for the stretched and un-stretched surface morphology of the Speedo FS-I swimsuit. Furthermore, the microscopic analysis of the stretched and un-stretched fabric was undertaken to extend our undertstanding

Renal involvement in HCV related cirrhosis evidenced as glomerular and tubular derangement

Introduction and Aims: The relation between HCV infection and glomerular damage is well recognized, with evidences of negative impact on renal function. HCV replication in renal tubular cells on kidney biopsies has been reported but very limited data are available on HCV-mediated tubular damage. The aim of the study was to assess the presence of renal involvement (RI), glomerular or tubular, in patients with HCV cirrhosis. Methods: 98 patients with HCV cirrhosis Child Pugh-A were consecutively enrolled. Glomerular filtration rate (eGFR) was estimated with CKD-EPI 2009 equation. Urinary albumin/creatinine (ACR) and alpha1microglobulin/creatinine (a1MCR) ratios were calculated. Glomerular involvement was defined based on ACR>20μg/mg, tubular involvement based on a1MCR>14μg/mg plus fractional sodium excretion (FeNa)>1%. Urine concentration of Liver-type Fatty Acid-Binding Protein (L-FABP) and Kidney injury molecule-1 (KIM-1) were examined in morning midstream urine samples (ELISA) and the values normalized to urine creatinine concentration as expression of tubular derangement. Results: eGFR was ≥60 mL/min/1.73 m2 in 92 patients (93.8%) and between 45-59 mL/min/1.73 m2 in 6 patients (6.1%). Glomerular involvement was found in 19 patients (19.4%), tubular involvement in 31 patients (31.6%) and these co-occurred in 10 patients ( p=0.034). Patients with glomerular or tubular involvement, or both, considered as patients with RI, showed significantly lower eGFR values ( p=0.005) (Tab 1). A ROC curve was drafted and a cut point of 90 ml/min predicted RI (AUC: 0.700; sensitivity 63%, specificity 75%). Patients with RI were older, had higher ACR and a1MCR levels and exhibited a higher KDIGO stage (Tab 1). No association was found between RI and: HCV-RNA levels, liver stiffness and liver function tests. L-FABP and KIM-1 levels were significantly higher in patients with RI. Conclusions: Tubular and/or glomerular involvement is quite frequent in HCV cirrhotic patients, despite a normal eGFR. The evidence of tubular involvement suggests an alternative localization of HCV as renal disease

3D anthropometric investigation of head and face characteristics of Australian cyclists

Design specialists have acknowledged the need for more accurate measurements of human anthropometry through the use of 3D data, especially for the design of head and facial equipment. However, 3D anthropometric surveys of the human head are sparse in the literature and practically non-existent for Australia. Research published to date has not proposed concrete methods that can accurately address the hair thickness responsible for inaccurate representation of the head's shape. This study used a state-of-theart handheld white light scanner to digitize 3D anthropometric data of 222 participants in the Melbourne Metropolitan Area. The participants volunteered for the study consisted of 46 females and 176 males (age: 34.6 ± 12.5). The participants' head scans were aligned to a standard axis system, whereby a Hair Thickness Offset (HTO) method was introduced to more accurately describe the true shape of the head. It is envisaged that the database constructed through this research can be used as a reference for the design and testing of helmets in Australia