Predicting the effect of voids on mechanical properties of woven composites

An accurate yet easy to use methodology for determining the effective mechanical properties of woven fabric reinforced composites is presented. The approach involves generating a representative unit cell geometry based on randomly selected 2D orthogonal slices from a 3D X-ray micro-tomographic scan. Thereafter, the finite element mesh is generated from this geometry. Analytical and statistical micromechanics equations are then used to calculate effective input material properties for the yarn and resin regions within the FE mesh. These analytical expressions account for the effect of resin volume fraction within the yarn (due to infiltration during curing) as well as the presence of voids within the composite. The unit cell model is then used to evaluate the effective properties of the composite

Forming low-cost, high quality carbon tows for automotive application

Carbon fiber reinforced composites are widely used in many industries due to their high performance. Its application in the aerospace industry has increased significantly, however, in mass produced automobile sector it is still limited. The current production of carbon fiber tow is slow and capital intensive. Thus, carbon manufactures produce higher tow counts to increase production rate to reduce its cost. In order to offset the higher cost of carbon fiber composite, an innovative and unique approach has been developed. The higher tow count carbon spools are split into smaller tow counts. Due to the delicate nature of carbon fiber, it is important to control the filamentation during that process. Different splitting process line strategies have been developed in this research work for understanding the process limitations and challenges involved. The process was made feasible for production by developing a fully automated process line with a laser feedback system. The system splits a 12K spool into two 6K tows. The quality of the 6K split tows has been determined statistically by recording real time data from the laser during the splitting process. It was demonstrated that the proposed process effectively controls filamentation and produces consistent tow quality

A review of advancements in synthesis, manufacturing and properties of environment friendly biobased Polyfurfuryl Alcohol Resin and its Composites

The quest for environmentally friendly and sustainable materials in the production of fibre reinforced composite materials has led to the use of biobased materials, which are easily accessible and renewable. Biomass-derived chemicals, their derivatives, and their applications have become increasingly prevalent in various industries and processes, greatly contributing to the goal of ecological sustainability. The biobased Polyfurfuryl Alcohol (PFA) resin is one of such polymeric materials that is gaining attention for composite applications due to its endearing Fire Smoke and Toxicity properties. Derived from agricultural by products such as sugar cane bagasse, it has been known for applications within the foundry, coating, and wood industries. However, there has been a growing interest in its use for fibre reinforced composite applications. For this reason, this work intends to provide a comprehensive review of the PFA resin in relationship to fibre reinforced composites applications. The work provides an in-depth discussion on the synthesis, curing process, manufacturing, and properties of the PFA resin as well as its composites

Characteristics, Risk Factors, and Treatment Practices of Known Adult Hypertensive Patients in Saudi Arabia

Objective. To determine the prevalence, risk factors, characteristics, and treatment practices of known adult hypertensives in Saudi Arabia. Methods. Cross-sectional community-based study using the WHO stepwise approach. Saudi adults were randomly chosen from Primary Health Care Centers catchment areas. Data was collected using a questionnaire which included sociodemographic data, history of hypertension, risk factors, treatment practices, biochemical and anthropometric measurements. Collected data was cheeked, computer fed, and analysed using SPSS V17. Results. Out of 4719 subjects (99.2% response), 542 (11.5%) subjects were known hypertensives or detected by health workers in the past 12 months. Hypertension was significantly associated with age, gender, geographical location, education, employment, diabetes, physical inactivity, excess body weight, and ever smoking. Multiple logistic analysis controlling for age showed that significant predictors of hypertension were diabetes mellitus, ever smoking, obesity, and hypercholesteremia. Several treatment modalities and practices were significantly associated with gender, age, education, and occupation. About 74% were under prescribed treatment by physicians, 62% on dietary modification, 37% attempted weight reduction, 27% performed physical exercise, and less than 7% used herbs, consulted traditional healers or quitted smoking. Income was not significantly associated with any treatment modality or patient practices. Conclusion. Hypertension (known and undetected) is a major chronic health problem among adults in Saudi Arabia. Many patients' practices need changes. A comprehensive approach is needed to prevent, early detect, and control the disease targeting, the risk factors, and predictors identified

Response to: "Renal biopsies should be performed whenever treatment strategies depend on renal involvement"

We thank Chemouny et al for their letter and concur with their conclusions. As we state (1): “A positive biopsy for AAV is helpful when considering an initial diagnosis or recurrent disease.” In our view, renal biopsy is important to establish diagnosis and may also provide an indication of prognostic trajectory and although existing classification systems need further validation, changes like glomerular sclerosis have obvious adverse prognostic value for patients with AAV (2-4). The Delphi process, for the scope of the current recommendations, identified the role of biopsy at both diagnosis and follow-up as an important item for update. Histopathological evidence of vasculitis, such as pauci-immune glomerulonephritis or necrotising vasculitis in any organ, remains the gold standard for diagnostic purposes. The likely diagnostic yield varies and is dependent on the organ targeted and in patients with GPA with renal involvement can be as high as 91.5% from renal biopsy (5). As Chemouny and colleagues have demonstrated, a renal biopsy was definitive in determining their management decisions. However during follow-up when relapses occur, it may be prudent to consider judicious use of further kidney biopsy during suspected renal relapse since the cause for acute kidney injury may be due to another cause other than AAV (6). Kind regards, M Yates, C Mukhtyar and DR Jayne on behalf of co-authors

Forming low-cost, high quality carbon tows for automotive application.

Carbon fiber reinforced composites are widely used in many industries due to their high performance. Its application in the aerospace industry has increased significantly, however, in mass produced automobile sector it is still limited. The current production of carbon fiber tow is slow and capital intensive. Thus, carbon manufactures produce higher tow counts to increase production rate to reduce its cost. In order to offset the higher cost of carbon fiber composite, an innovative and unique approach has been developed. The higher tow count carbon spools are split into smaller tow counts. Due to the delicate nature of carbon fiber, it is important to control the filamentation during that process. Different splitting process line strategies have been developed in this research work for understanding the process limitations and challenges involved. The process was made feasible for production by developing a fully automated process line with a laser feedback system. The system splits a 12K spool into two 6K tows. The quality of the 6K split tows has been determined statistically by recording real time data from the laser during the splitting process. It was demonstrated that the proposed process effectively controls filamentation and produces consistent tow quality.Company research funding by Bentley Motors Limite

Predicting the effect of voids on mechanical properties of woven composites.

An accurate yet easy to use methodology for determining the effective mechanical properties of woven fabric reinforced composites is presented. The approach involves generating a representative unit cell geometry based on randomly selected 2D orthogonal slices from a 3D X-ray micro-tomographic scan. Thereafter, the finite element mesh is generated from this geometry. Analytical and statistical micromechanics equations are then used to calculate effective input material properties for the yarn and resin regions within the FE mesh. These analytical expressions account for the effect of resin volume fraction within the yarn (due to infiltration during curing) as well as the presence of voids within the composite. The unit cell model is then used to evaluate the effective properties of the composite.DelPHE 780 Project funded by UK Department of International Development (DFID), through British Council managed DelPHE scheme

Regional Integration of Equity Markets in Sub-Saharan Africa

Equity markets in developing and emerging economies have grown in number and importance as a result of financial market globalisation. However, their role in economic growth and development is enhanced if nascent markets are integrated with well-established ones. Market integration, measured by the transmission of returns volatility, is identified across a sample of SSA countries, using a unique dataset. Evidence for potential integration between financial markets in Sub-Saharan Africa (SSA) is found. Spillovers are found across markets, some unidirectional and others bi-directional. However, continued illiquidity and incomplete institutions indicate that an integrated financial community remains premature, and considerable regulatory reform and harmonisation will be necessary for this to succeed

The potential and environmental benefits of developing renewable energy strategy: a comparative analysis of Pakistan and developed countries

Renewable energy is being developed globally to overcome the depletion of natural resources and mitigating the global issue of climate change. The increasing energy crisis and environmental concerns make renewable energy more critical for a sustainable future. Renewable energy technologies have a great potential across the globe. Pakistan being a developing country is continuously facing energy crisis and an emphasis on industrialization is increasing carbon emissions. Renewable energy development provides necessary solutions, particularly in developing countries where energy demands have to be met through an economical and environmental friendly way. This paper explores the significance and potential of renewable energy development in developing countries i.e. Pakistan and how it can contribute to reduce the environmental impacts for mitigating climate change. It argues that the current policy measures and infrastructure is inadequate to implement renewable energy technologies, also discussing various renewable energy sources. The critical review of the literature and case-based experiences has been used as an overall approach to this paper. It will help in exploring renewable energy strategy and its implementation in developing countries in comparison to developed economies. It concludes with an integrated and comprehensive policy recommendations and possible solutions to develop a strategic approach to renewable energy