Effect Of Different Geometries Research Articles

Inelastic Solution for Power Law Fluid with Taylor Galerkin-Pressure Correction Finite Element Method: Axisymmetric Contraction Flows

In this study we examine the flow of inelastic fluids with various shear properties in axisymmetric contractions with various contraction ratios are selected as 4:1, 6:1 and 8:1 with both rounded-corner and sharp. Particular attention is paid to the effect of shear thickening and shear thinning upon the solution behavior. Power-law inelastic model is employed coupling with the conservation of momentum equation and continuity equation. The numerical simulation of such fluid is performed by using the Taylor Galerkin pressure correction (T-G/P-C) finite element algorithm. The effects of geometry structure and many factors such as Reynolds number (Re) and the parameters of power law model are presented in this study. Particularly, in this study we are focused on the influence of these factors on the solution components and the level of convergence. This research was a comparative study between sharp and rounded-corner contraction geometries with a ratio of 4:1, and to another comparative study among sharp contraction geometries with ratios of 4:1, 6:1, and 8:1. The practical implications of this study focused on vortex length and the impact of varying the parameters of the power law model and the Reynolds number (Re) on it for 4:1 contraction flow. The study dealt with the effect of different geometries on the rates of convergence of velocity and pressure as well as the characteristics of axial velocity and pressure on the axis of symmetry.

Parametric design, simulation, fabrication, and test of an Origami-core based sandwich composite material

Sandwich panel structures are widely used for light-weight applications due to their high strength and stiffness to density ratios. They are composed of two main parts: the skins and the core. This paper investigates a Miura-ori structural sandwich core with open cells that can be used as an alternative to the existing honeycomb structures. A fully parametric design approach, starting from drawing to Finite Element Analysis (FEA), is presented to efficiently analyze the effect of different geometries on the resulting structure. The geometric model was built based on the kinematic model, which can represent the folding process of the foldcore using the Matlab script. The obtained coordinates of the vertices of the folding pattern were exported to ANSYS APDL where the surfaces were automatically created and meshed. The created mesh was imported to LS-Dyna where explicit compression analyses were performed to evaluate the compression stiffness and strength of the studied geometries. The developed parametric model aims to find the best configuration for a given application, based on three sets of geometric parameters that define the shape of the Miura Ori folding pattern. Therefore, in the range of the studied geometries, the best parameter combination for specific compression stiffness and specific compression strength was found. To evaluate the performance of the foldcore and to validate the FE model, experimental quasi-static compression tests were undertaken with two kinds of specimens (‘strip’ and “panel”), and the measured force-displacement curves were obtained. The result of the test agrees with that of the FE simulations, with an error of <6.6% in the elastic region.

Prediction of Mechanical Behavior of Epoxy Polymer Using Artificial Neural Networks (ANN) And response Surface Methodology (RSM)

The aim of this study is to analyze the effect of different geometries and sections on the mechanical properties of epoxy specimens. Five tensile tests were carried out on three types of series. The experimental results obtained were 1812.21 MPa, 3.90% and 41.91 MPa for intact specimens, 1450.41 MPa, 2.16% and 21.28 MPa for specimens with hole and 750.77 MPa, 2.77% and 11.89 MPa for specimens with elliptical -notched for Young's modulus, strain and stress respectively. In addition, the experimental results indicated that the mechanical properties of both (Young's modulus value and stress value) were higher in an intact specimen. Afterwards, the nonlinear functional relationship of input parameters between epoxy sample geometries and sections was established using the response surface model (RSM) and the artificial neural network (ANN) to predict the output parameters of mechanical properties (Young's modulus and stress). In addition, the design of experiment was developed by the Analysis of the Application of Variance (ANOVA). The results showed the superiority of the ANN model over the RSM model, where the correlation coefficient values for the model datasets exceed ANN (R2 = 0.984 for Young's modulus and R2 = 0.981 for the constraint).

Geometrically nonlinear effect on forced vibrational behavior of superlight composite beams with auxetic core layer under harmonic excitation based on FSDT

The growing use of light composite materials in different industries such as automotive and aerospace has caused the need for more studies to analyze their behavior. In this study, an analytical solution for the nonlinear forced vibrational behavior of a multilayered superlight composite beam with a honeycomb core layer and adjustable Poisson’s ratio subjected to a harmonic excitation has been presented. The beam has two isotropic upper and lower layers with one honeycomb core layer. The Poisson’s ratio of the honeycomb core layer can be adjusted by changing the honeycomb cell parameters in a range of negative to positive values. The equations of motion have been extracted using the first-order shear deformation theory and nonlinear von Kármán relations. The equations are a system of coupled nonlinear partial differential equations that have been solved using the perturbation technique. To investigate the effect of different geometry and honeycomb cell parameters on the nonlinear response, a parametric study has been conducted. The effect of nonlinearity on the chaotic behavior and primary resonance is studied. The finite element method has been used to compare the results. It is observed that by adding a honeycomb layer, the total weight has been dropped by about 50% while the dynamic responses nearly remain the same.

Selection of Bifurcated Grafts' Dimensions during Aorto-Iliac Vascular Reconstruction Based on Their Hemodynamic Performance.

During the vascular surgical reconstruction of aorto-iliac occlusive/aneurysmal disease, bifurcated grafts are used where vascular surgeons intra-operatively select the size and the relative lengths of the parent and daughter portions of the graft. Currently, clinical practice regarding the selection of the most favorable geometric configuration of the graft is an understudied research subject: decisions are solely based on the clinical experience of the operating surgeon. This manuscript aims to evaluate the hemodynamic performance of various diameters, D, of bifurcated aortic grafts and relate those with proximal/distal part length ratios (the angle φ between the limbs is used as a surrogate marker of the main body-to-limb length ratio) in order to provide insights regarding the effects of different geometries on the hemodynamic environment. To this end, a computationally intensive set of simulations is conducted, and the resulting data are analyzed with modern statistical regression tools. A negative curvilinear relationship of TAWSS with both φ and D is recorded. It is shown that the angle between limbs is a more important predictor for the variability of TAWSS, while the graft's diameter is an important determinant for the variability of OSI. Large percentages of the total graft area with TAWSS < 0.4 Pa, which correspond to thrombogenic stimulating environments, are only observed for large values of φ and D > 20 mm. This variable ranges from 10% (for the smallest values of φ and D) to 55% (for the largest φ and D values). Our findings suggest that grafts with the smallest possible angle between the limbs (i.e., smallest parent-to-daughter length ratio) present the most favorable hemodynamic performance, yielding the smallest percentage of total graft area under thrombogenic simulating environments. Similarly, grafts with the smallest acceptable diameter should be preferred for the same reason. Especially, grafts with diameters greater than 20 mm should be avoided, given the abrupt increase in estimated thrombogenic areas.

The effect of geometry on fretting fatigue test results in Al7075-t651 specimens with cylindrical contact

Fretting fatigue is a material damage phenomenon that produces damage on the contact surface, such as wear and surface cracks that can grow through the specimen. It is possible to reproduce the phenomenon in a laboratory using different geometries. In the absence of a common guide, this work studies the effect of different geometries of specimens and contact pairs on the fretting fatigue behaviour. This paper compares the results of a fretting fatigue test campaign made with cylindrical contact pairs made of AL7075-T651 alloy. In addition, 3D numerical models are developed to analyse the stress/strain fields and asses the total life. According to the experimental and numerical results, the differences of total life obtained between the geometries considered are negligible.

Thermoformability analysis of TPO sheets blended with postindustrial secondary feedstock

AbstractProduction scrap is a significant cost for automotive thermoforming due to the expensive resin costs and large part sizes. Manufacturers strive to regrind and reprocess sheet cutouts from production runs, however, the utilization of a secondary feedstock can be limited by its impact on the sheet processing behavior. To mitigate the economic impact of production scrap, the thermoformability of a blend needs to be predicted at the material development stage. In this work, a test mold is designed to assess the thermoformability of blended TPO sheets. The mold design is developed to evaluate the effects of different geometries. Regrind content is introduced in the blend before extrusion to compare the sheet properties to those of a virgin material configuration. The statistical analysis of the thermoforming experiments shows that the sheet thickness reduction is affected by the draw ratio and sheet temperature. Multivariate regression modeling allows for predicting the thermoformed part thickness as a function of the sheet configuration, draw ratio, and processing conditions. However, the introduction of regrind content, below 50%, did not affect thermoformability. The stretchability of the sheets was also characterized by uniaxial tensile testing and dynamic mechanical analysis, confirming the absence of negligible differences when regrind content is introduced in the blend.

Synthesis and characterisation of magnesium-based nano-composite – A review

In the recent decades, the need for light weight and high specific strength has been the hot issue in many engineering field and also biomedical sectors. Magnesium and its alloys are considered as a light weight material due to its low density that can replaced aluminium, steel and titanium. However, at room temperature, magnesium alloys have closely packed hexagonal crystalline structure with restricted number of freely actuated independent slip system that suffers from poor ductility by 5%–8% approximately. Therefore, Magnesium alloy creates some challenges for the application of many industrial sectors. One technique that can improve strength properties without significant reduction of ductility is to add reinforcing nanoparticles within the magnesium matrix and making them an attractive choice for light weight structural application. The performance of magnesium matrix-based composites to a current stage depends upon the proper selection of composition and combination of reinforcement particles within the matrix materials. In light of the writing overview, the inclusion of reinforcing particles, for example, TiC, SiC, B4C, Al2O3, hybrid reinforcement and so forth is the way to betterment of the tribological behaviour and the mechanical properties of magnesium matrix composites. This paper presents a brief overview based on the available literature survey that the effect of different geometries and percentage contribution of reinforcement particles in various processing techniques on the mechanical properties, microstructure and wear behaviour of magnesium-based metal composites.

Recent Development and Future Prospective of Tiwari and Das Mathematical Model in Nanofluid Flow for Different Geometries: A Review

The rapid changes in nanotechnology over the last ten years have given scientists and engineers a lot of new things to study. The nanofluid constitutes one of the most significant advantages that has come out of all these improvements. Nanofluids, colloid suspensions of metallic and nonmetallic nanoparticles in common base fluids, are known for their astonishing ability to transfer heat. Previous research has focused on developing mathematical models and using varied geometries in nanofluids to boost heat transfer rates. However, an accurate mathematical model is another important factor that must be considered because it dramatically affects how heat flows. As a result, before using nanofluids for real-world heat transfer applications, a mathematical model should be used. This article provides a brief overview of the Tiwari and Das nanofluid models. Moreover, the effects of different geometries, nanoparticles, and their physical properties, such as viscosity, thermal conductivity, and heat capacity, as well as the role of cavities in entropy generation, are studied. The review also discusses the correlations used to predict nanofluids’ thermophysical properties. The main goal of this review was to look at the different shapes used in convective heat transfer in more detail. It is observed that aluminium and copper nanoparticles provide better heat transfer rates in the cavity using the Tiwari and the Das nanofluid model. When compared to the base fluid, the Al2O3/water nanofluid’s performance is improved by 6.09%. The inclination angle of the cavity as well as the periodic thermal boundary conditions can be used to effectively manage the parameters for heat and fluid flow inside the cavity.

A numerical model for diesel engine SCR systems under different inlet NH3 distribution profiles

Selective Catalytic Reduction (SCR) technology is currently used to effectively reduce NOx emissions for diesel engines. The present study aims at building a three-dimensional numerical model to evaluate the NOx conversion efficiency and the NH3 slip in an SCR system, reducing the time and resources necessary for design and development process. A numerical model of an SCR system has been built to integrate species transport, heat transfer and flow characteristics along with kinetics of the chemical reactions. In order to systematically simulate situations where the concentration of NH3 at the inlet is not uniform, different NH3 inlet profiles have been built by using a Multivariate Gaussian Distribution and considering the maximum concentration in different locations. The effect of different geometries and NH3 distribution profiles on the NOx conversion efficiency and NH3 slip has been studied. The behaviour of the system at different inlet temperatures has been explored and the reaction rates in the monolith have been analysed. The study has been extended by studying the effect of different NH3/NO ratios to provide a more complete comparison between different designs. The numerical model has been found useful to take into account many aftertreatment system parameters during the design of an SCR system, maximize the NOx conversion efficiency by modifying the NH3/NO ratio while minimizing the NH3 slip, providing a comprehensive tool for the optimization of geometrical characteristics of an SCR system.

Numerically Evaluation of Dynamic Behavior of Post-Tensioned Concrete Flat Slabs under Free Vibration

The objective of this paper is to investigate the dynamic behaviour of post-tensioned concrete flat slabs with different geometries and damping ratios. Four groups of models with different lengths, widths, thicknesses and damping ratios designed according to the AS3600 standard. These were used to determine the influence of each parameter on the vibration serviceability by comparing the control variable method with the reference model. The vibration assessment parameters were used as natural frequency, peak acceleration, and response factor. Both the SCI/CSTR43 standard theoretical calculations method and the Strand7 finite element analysis (FEA) method are used to determine the effect of different geometries and damping ratios on vibration. The feasibility of the Strand7 FEA method for vibration analysis is also assessed by calculating the errors of the two methods. The paper concludes that the Strand7 FEA method is highly accurate and feasible. The span in both directions has a large effect on the natural frequency, and increasing both the slab thickness and the damping ratio are effective methods to improve the vibration serviceability. Based on the research in this paper, recommendations are provided for future vibration design of post-tensioned concrete slabs.

Numerical Parametric Study and Design of Pultruded GFRP Composite Channel Columns

This article reports the finite element (FE) investigation of the axial capacities of pultruded fiber-reinforced polymer (PFRP) composite channel columns. The nonlinear finite element model (FEM) was developed by using the ABAQUS package for glass fiber-reinforced polymer (GFRP) composite channel columns, which included geometric and initial geometric imperfections. The developed FEMs were verified against an experimental result available in the literature for GFRP channel columns. The validated FEMs were used to carry out the parametric study comprising 61 FE models to investigate the effect of different geometries, plate slenderness and the length of members on the axial capacities of GFRP pultruded channel columns. The results obtained from the parametric study were used to examine the accuracy of the current Italian guidelines, American pre-standard and the Direct Strength Method (DSM) proposed in the literature for GFRP channel profiles. Based on the obtained results, the suitability of the current design guidelines is assessed and, also, a new set of design equations is proposed to estimate the axial capacity of the pultruded GFRP channel columns. The new proposed set of reliable design equations witnessed a less scattered and a high degree of accuracy in determining the axial load capacity of the pultruded GFRP composite channel columns.

Numerical Study of Road Embankment Type Action on Shear Stress Around Skewed Bridge Abutment

This paper investigates the effect of different geometries of approach embankments and guides banks on the flow pattern and bed shear stress values in the skewed bridges in the compound channel using three-dimensional numerical modelling. First, the numerical model was evaluated based on the results of existing laboratory studies. After ensuring its proper performance, the elliptical guide bank and the three types of abutments: vertical-wall, spill-through, and wing-wall, at different skew angles are examined. Investigation of the values of maximum velocity and bed shear stress at the flow-conducting embankment and the flow-splitting embankment showed that in the flow-conducting embankment, the best performance is assigned to the elliptical guide bank. In contrast, the performance of various abutments is different for the flow-splitting embankment depending on the skew angle of the bridge. Then, different patterns based on streamlines for the geometry plan of the guide bank were proposed and studied. The results show that the most suitable pattern for the guide bank reduces the maximum flow velocity by up to 15% and reduces the maximum bed shear stress by up to 80% around the flow-splitting embankments.

Predicting powder feedability: A workflow for assessing the risk of flow stagnation and defining the operating space for different powder-feeder combinations

Powder feeding is of critical importance for continuous manufacturing (CM) since next to in-process segregation it is the phenomenon primarily responsible for fluctuations in content uniformity and for content deviations in the final drug product. So far, feeding studies have focused on the characterization of specific feeders and the prediction of their performance for various materials. This work presents a more holistic approach, an early general assessment of the “feedability” of raw materials. With that regard, we established a workflow to: i) predict potential feeding issues, such as the flow stagnation in the hopper based on both the material attributes and the feeder’s geometry; and ii) predict the feed rate space using various feeder/screw combinations for powders with an acceptable risk of hopper flow stagnation. Statistical models were developed for this twofold approach using a dataset comprising nine powders and four different feeders. In order to include different feeding equipment into the statistical models, novel equipment descriptors (capturing the effect of different geometries) and performance indicators (the end fill level as indicator for the risk of powder flow stagnation) were introduced. The application of the workflow was demonstrated for a simple formulation, and model validation was successfully performed for an additional powder that was not contained in the original dataset. Finally, the most relevant material attributes were identified, and reduced material characterization data sets were investigated in terms of effects on the model’s prediction performance. The workflow presents a promising tool for initial process assessment in early-phase development.

Importance of nanochannels shape on blue energy generation in soft nanochannels

Energy production is one of today's most pressing issues. Finding alternative energy sources has become one of the hottest research areas for scholars due to the limited use of fossil resources. Using water sources of different concentrations is one of the newest methods of energy production. Due to the energy of mixing fluids, two fluids of different concentrations on both sides of a nanochannel membrane can produce energy. Given the costs and restrictions of studying complex systems experimentally, simulation is required to investigate their behavior and determine the best states. As a result, using an energy production strategy, this work explores the effect of nanochannel shape on the ion transfer behavior. Asymmetric (bullet, trumpet, cigarette, hourglass, and hill) and symmetric (cylindrical) geometries were utilized. The effects of different geometries, soft layer density, and concentration ratio on energy production considering the effect of ion partitioning in soft surfaces was investigated. A finite element numerical computation approach was employed to solve the Poisson-Nernst-Planck and Navier-Stokes equations at steady-state. The best geometry at various concentration ratios to create the most performance were: cylindrical and cigarette for osmotic current, hourglass and trumpet for transmission number, hourglass and trumpet for diffusion potential, cylindrical for electrical conductivity, cylindrical and trumpet for power capacity, and hourglass and trumpet for energy conversion efficiency, respectively. In the case of considering the ion partitioning at a concentration ratio of CH/CL=1000for trumpet geometry, raising the soft layer's charge density from NPEL/NA=25to100mol/m3 boosted the maximum produced power by about 25 times, from 0.215pW to 5.35pW.

Antioxidant Properties of SLA Printed Hydrogels Enriched with Pomegranate Powder

3D printing (3DP) is a powerful platform for fabrication of complex or personalized geometries. Hydrogels as attractive candidates for wound dressing, soft implant, encapsulation of phenolic compounds, drug delivery, etc. could be manufactured by using different 3D printing techniques. In this study, encapsulation of pomegranate powder into PEGDMA gel by Stereolithography (SLA) printing was investigated and then antioxidant activity and total phenolic content of printed gels with varying shapes were examined to see the effect of different geometry and process conditions. According to the results, pomegranate based blend was successfully incorporated into gel matrix and printed with high printability ratio at optimized 3D printing conditions. UV induced gelation did not prevent existence of phenolic compounds and allowed retention of antioxidant potential in printed samples. Obtained hydrogels represent promising biomaterials with great potential for the use in different applications such as antioxidant gel for tissue engineering, wound healing or as a nutraceutical carrier.

Processing, thermal conductivity and flame retardant properties of silicone rubber filled with different geometries of thermally conductive fillers: A comparative study

With the development of highly integrated and miniaturized electronic devices, silicone rubber composites with good mechanical flexibility, high thermal conductivity and excellent flame resistance have aroused considerable interest in both industrial and research community. However, the effect of different geometries of thermally conductive fillers on the processing, mechanical and thermal properties as well as flame resistance of silicone rubber composites is still not clear. Herein, liquid silicone rubber (LSR) composites filled with three geometries of thermal conductive fillers i.e. spherical-like aluminum oxide (Al 2 O 3 ), irregular aluminum nitride (AlN) and 2D boron nitride (BN) sheets were prepared by an extremely simple mechanical-mixing process. As expected, incorporation of BN sheets into LSR matrix produces much higher increase in the viscosity, tensile strength and hardness than the corresponding AlN and Al 2 O 3 fillers, respectively. Typically, at a fixed filler loading of 120 phr, the increased thermal conductivity and heating/cooling efficiency of the BN/LSR composites display much better than the corresponding AlN/LSR and Al 2 O 3 /LSR composites, e.g. 316, 124 and 88% improvement in thermal conductivity, respectively. Interestingly, the thermal stability and flame resistance of the three composites present unexpected different phenomena. Compared with the pure LSR, the addition of AlN and Al 2 O 3 exacerbates the thermal degradation of LSR chains, while the presence of BN sheets improves the flame resistance of LSR dramatically, which is attributed to the compact BN/silica residue after burning that effectively restricts the heat and oxygen to attack the inside LSR chains.

A new equivalent sand grain roughness relation for two-dimensional rough wall turbulent boundary layers

The effects of different geometries of two-dimensional (2-D) roughness elements in a zero pressure gradient (ZPG) turbulent boundary layer (TBL) on turbulence statistics and drag coefficient are assessed using single hot-wire anemometry. Three kinds of 2-D roughness are used: (i) circular rods with two different heights, $k= 1.6$ and 2.4 mm, and five different streamwise spacing of $s_{x}= 6k$ to $24k$ , (ii) three-dimensional (3-D) printed triangular ribs with heights of $k= 1.6$ mm and spacing of $s_{x}= 8k$ and (iii) computerized numerical control (CNC) machined sinewave surfaces with two different heights, $k= 1.6$ and 2.4 mm, and spacing of $s_{x}= 8k$ . These roughnesses cover a wide range of ratios of the boundary layer thickness to the roughness height ( $23 &lt; \delta /k &lt; 41$ ), where $\delta$ is the boundary layer thickness. All roughnesses cause a downward shift on the wall-unit normalised streamwise mean velocity profile when compared with the smooth wall profiles agreeing with the literature, with a maximum downward shift observed for $s_{x}= 8k$ . In the fully rough regime, the drag coefficient becomes independent of the Reynolds number. Changing the roughness height while maintaining the same spacing ratio $s_{x}/k$ exhibits little influence on the drag coefficient in the fully rough regime. On the other hand, the effective slope $(ES)$ and the height skewness $(k_{sk})$ appear to be major surface roughness parameters that affect the drag coefficient. These parameters are used in a new expression for $k_{s}$ , the equivalent sand grain roughness, developed for 2-D uniformly distributed roughness in the fully rough regime.

Numerical study and design rule for axial capacities of pultruded GFRP hollow columns

This article reports the finite-element (FE) investigation on the axial capacities of pultruded fibre reinforced polymer (PFRP) composite hollow columns. The non-linear finite-element model (FEM) was developed by using ANSYS package for glass fibre reinforced polymer (GFRP) composite hollow columns, which included geometric and initial geometric imperfections. The developed FEMs were verfied against an experimental results available in the literature for GFRP hollow columns. The validated FEMs were used to carry out the parametric study comprising 92 FE models to investigate the effect of different geometries, plate slenderness and length of members on the axial capacities of GFRP pultruded hollow columns. The axial capacities predicted by the nonlinear FE analysis were also used to examine the accuracy/applicability of the current design guidelines for GFRP pultruded hollow columns available in the literature. Based on the comparison of results the merits and demerits of existing design rules in literature are discussed. In addition, this article proposed a simplified design approach over the existing strength equations to predict the axial capacity of GFRP pultruded hollow columns. The proposed design equations have closely predict the axial capacities of GFRP pultruded hollow columns, being only 9% conservative to the FEA strengths.

Contribution of the dipole–dipole interaction to targeting efficiency of magnetite nanoparticles inside the blood vessel: A computational modeling analysis with different magnet geometries

The widespread use of magnetite nanoparticles inside the bloodstream for diagnostic and therapeutic purposes has made the influence of the interaction forces between these nanoparticles an important issue for predicting their behavior for improving the effectiveness of the protocols. Magnets with various geometries have been used in different biomedical applications, such as targeted drug delivery, to guide drugs carrying magnetite nanoparticles to specific areas. In this regard, using computational modeling, we have employed a multiphysics modeling approach using the particle tracing module in the COMSOL software environment to investigate the behavior of magnetite nanoparticles considering not only the magnetophoretic force, but also the dipole–dipole interaction forces between the nanoparticles. The effects of different geometries of magnets on the induced magnetic flux density and the laminar flow velocity inside the bloodstream were studied as well. The results of our study show that each geometry of the magnet induces different magnetic flux density profile and laminar velocity inside the blood flow. The behavior of ferrofluid flow is dependent on the geometry of the magnet and its remanent flux density. By increasing the size of magnetic nanoparticles, the magnetophoretic force enhances the particle velocity in the direction perpendicular to the vessel's walls, which could result in pull out. The results also reveal that the magnetic dipole–dipole interactions between nanoparticles could lead to the induction of higher dipole–dipole interaction forces in regions close to the magnet, especially on the upper wall of the blood vessel.