Finite element analysis of filament-wound composite pressure vessel under internal pressure

In this study, finite element analysis (FEA) of composite overwrapped pressure vessel (COPV), using commercial software ABAQUS 6.12 was performed. The study deals with the simulation of aluminum pressure vessel overwrapping by Carbon/Epoxy fiber reinforced polymer (CFRP). Finite element method (FEM) was utilized to investigate the effects of winding angle on filament-wound pressure vessel. Burst pressure, maximum shell displacement and the optimum winding angle of the composite vessel under pure internal pressure were determined. The Laminae were oriented asymmetrically for [00,00] s, [150,-150]s, [30 0,-300]s, [450,-450] s, [550,-550]s, [60 0,-600]s, [750,-750] s, [900,-900]s orientations. An exact elastic solution along with the Tsai-Wu, Tsai-Hill and maximum stress failure criteria were employed for analyzing data. Investigations exposed that the optimum winding angle happens at 550 winding angle. Results were compared with the experimental ones and there was a good agreement between them. © Published under licence by IOP Publishing Ltd.S Sulaiman, S Borazjani and S H Tan

Bioremediation and Leaching Potential of Pentachlorophenol (PCP) in Biodiesel Versus Diesel Carriers

Biodiesel is believed to be more environmentally friendly than petroleum-based diesel when used as a carrier for impregnating wood products with pentachlorophenol (PCP) for decay protection. A 6-mo study was conducted to evaluate bioremediation of PCP in biodiesel vs diesel in soil. Different percentages of biodiesel, diesel, and PCP were mixed with clean soil from a forested site and tested. Samples were taken bimonthly and analyzed for oil and grease, PCP concentration, and microbial enumeration. Soil moisture content was adjusted twice weekly if needed. In addition, toxicity and toxicity characteristic leaching potential were measured at Days 0 and 180. Results showed that with an increase in percentage of biodiesel, there was an increase in degradation of diesel and diesel-amended PCP. The greatest decrease of PCP concentration and toxicity occurred in biodiesel alone by Day 180. Results also showed a significant decrease with time in oil and grease concentration, PCP concentration, and toxicity among different treatments. Based on this study, it appears that the cometabolic effect of biodiesel on micro-organisms could accelerate degradation of PCP in treated wood after disposal

Milk and Protein Intake by Pregnant Women Affects Growth of Foetus

The study assessed the effects of the daily intake of milk and protein by pregnant women on foetal growth and determined the growth pattern and velocity of growth. A total of 504 ultrasound observations from 156 respondents were collected following a cross-sectional design in the last trimester of pregnancy; majority of them were in the last month of pregnancy. De facto and purposive sampling was done, and direct interviews of affluent pregnant women were conducted. Kruskal-Wallis test shows that majority of the respondents had tendency to consume 155.65 to 465.17 mL of milk per day, resulting in better and higher foetal growth. Most respondents consumed about 50-70 g of protein per day, and the foetal growth measurements, such as abdomen-circumference, femur length, biparietal diameter, and head-circumference, on an average, were higher in the same group. Quadratic regression model exhibited that all the traits of growth pattern in Model 1 (low milk and protein intake) appeared to have more mode of decline, in contrast to Model 2 (more milk and protein intake), which shows better growth. In addition, velocity of growth pattern was obtained through the first derivative of quadratic regression of growth pattern. Moreover, 95% confidence interval calculated for regression line slope of Model 1 and Model 2 showed that the estimation point (2 B2) of Model 1 does not lay into 95% CI of Model 2; so, statistical significance assorted and also the same trend conversely hold for Model 2. The rate of growth was highly influenced by maternal milk and protein intake. These findings suggest that contribution of common nutrients or other nutritional factors present in milk and protein promote the growth of foetus

Fluid-structure interaction simulation of prosthetic aortic valves : comparison between immersed boundary and arbitrary Lagrangian-Eulerian techniques for the mesh representation

In recent years the role of FSI (fluid-structure interaction) simulations in the analysis of the fluid-mechanics of heart valves is becoming more and more important, being able to capture the interaction between the blood and both the surrounding biological tissues and the valve itself. When setting up an FSI simulation, several choices have to be made to select the most suitable approach for the case of interest: in particular, to simulate flexible leaflet cardiac valves, the type of discretization of the fluid domain is crucial, which can be described with an ALE (Arbitrary Lagrangian-Eulerian) or an Eulerian formulation. The majority of the reported 3D heart valve FSI simulations are performed with the Eulerian formulation, allowing for large deformations of the domains without compromising the quality of the fluid grid. Nevertheless, it is known that the ALE-FSI approach guarantees more accurate results at the interface between the solid and the fluid. The goal of this paper is to describe the same aortic valve model in the two cases, comparing the performances of an ALE-based FSI solution and an Eulerian-based FSI approach. After a first simplified 2D case, the aortic geometry was considered in a full 3D set-up. The model was kept as similar as possible in the two settings, to better compare the simulations' outcomes. Although for the 2D case the differences were unsubstantial, in our experience the performance of a full 3D ALE-FSI simulation was significantly limited by the technical problems and requirements inherent to the ALE formulation, mainly related to the mesh motion and deformation of the fluid domain. As a secondary outcome of this work, it is important to point out that the choice of the solver also influenced the reliability of the final results

Immersed boundary-finite element model of fluid-structure interaction in the aortic root

It has long been recognized that aortic root elasticity helps to ensure efficient aortic valve closure, but our understanding of the functional importance of the elasticity and geometry of the aortic root continues to evolve as increasingly detailed in vivo imaging data become available. Herein, we describe fluid-structure interaction models of the aortic root, including the aortic valve leaflets, the sinuses of Valsalva, the aortic annulus, and the sinotubular junction, that employ a version of Peskin's immersed boundary (IB) method with a finite element (FE) description of the structural elasticity. We develop both an idealized model of the root with three-fold symmetry of the aortic sinuses and valve leaflets, and a more realistic model that accounts for the differences in the sizes of the left, right, and noncoronary sinuses and corresponding valve cusps. As in earlier work, we use fiber-based models of the valve leaflets, but this study extends earlier IB models of the aortic root by employing incompressible hyperelastic models of the mechanics of the sinuses and ascending aorta using a constitutive law fit to experimental data from human aortic root tissue. In vivo pressure loading is accounted for by a backwards displacement method that determines the unloaded configurations of the root models. Our models yield realistic cardiac output at physiological pressures, with low transvalvular pressure differences during forward flow, minimal regurgitation during valve closure, and realistic pressure loads when the valve is closed during diastole. Further, results from high-resolution computations demonstrate that IB models of the aortic valve are able to produce essentially grid-converged dynamics at practical grid spacings for the high-Reynolds number flows of the aortic root

National Outbreak of Acanthamoeba Keratitis Associated with Use of a Contact Lens Solution, United States

Premarket standardized testing for Acanthamoeba spp. is warranted

Light-Weight Design Application: Design of a composite vehicle roof and analysis in the frontal crash

Nowadays, light-weight design has absorbed attentions in automotive industry due to its beneficial impacts such as reducing fuel consumption and CO2 emission and, at the same time, maintain or even improve structural efficiency and performance. Beside other materials, such as aluminum, which can be used in light-weight design, composites play an important role due to their high strength, low weight and more durability. In this paper efforts have been made to investigate the design of a roof panel with different composite material solutions paying particular attention to its response in the car frontal crash. The roof panel modeling is carried out in the explicit finite element code LS-DYNA, which is suitable for crashworthiness analysis, with three material solutions of steel (that being the normal production solution will be the reference), aluminum and composite. MAT 24 "Piecewise Linear Plasticity" is applied to model the steel and aluminum roof panels which is an elasto-plastic material model that can analyze failure based on plastic strain. MAT 54 "Enhanced Composite Damage" along with the Chang-Chang failure criterion is utilized to model the composite roof. This material model is quite common to model composite material because it reduces the number of experimental input parameters compared to damage mechanics-based material models and it can develop the progressive failure and material degradation during the crash. Roof sections are defined near the car body pillars to obtain the results in a wide range and ease to compare set of data. Results including section forces, section displacements and roof absorbed energy are computed and compared for different materials. Results reveal that the composite roof has almost similar response with aluminum and steel panels in frontal crash but is giving larger contribution to vehicle stiffnes

Light-Weight Design Application: Design of a composite vehicle roof and analysis in the frontal crash

Nowadays, light-weight design has absorbed attentions in automotive industry due to its beneficial impacts such as reducing fuel consumption and CO2 emission and, at the same time, maintain or even improve structural efficiency and performance. Beside other materials, such as aluminum, which can be used in light-weight design, composites play an important role due to their high strength, low weight and more durability. In this paper efforts have been made to investigate the design of a roof panel with different composite material solutions paying particular attention to its response in the car frontal crash. The roof panel modeling is carried out in the explicit finite element code LS-DYNA, which is suitable for crashworthiness analysis, with three material solutions of steel (that being the normal production solution will be the reference), aluminum and composite. MAT 24 ”Piecewise Linear Plasticity” is applied to model the steel and aluminum roof panels which is an elasto-plastic material model that can analyze failure based on plastic strain. MAT 54 “Enhanced Composite Damage” along with the Chang-Chang failure criterion is utilized to model the composite roof. This material model is quite common to model composite material because it reduces the number of experimental input parameters compared to damage mechanics-based material models and it can develop the progressive failure and material degradation during the crash. Roof sections are defined near the car body pillars to obtain the results in a wide range and ease to compare set of data. Results including section forces, section displacements and roof absorbed energy are computed and compared for different materials. Results reveal that the composite roof has almost similar response with aluminum and steel panels in frontal crash but is giving larger contribution to vehicle stiffness