scholarly journals Engineering calculations for complex geometric domains

2018 ◽  
Vol 157 ◽  
pp. 02009 ◽  
Author(s):  
Elzbieta Gawronska ◽  
Robert Dyja ◽  
Andrzej Grosser ◽  
Jerzy Winczek
Keyword(s):  
Volume Fraction ◽  
Layer By Layer ◽  
The Finite Element Method ◽  
Compound Structure ◽  
Software Module ◽  
Volume Percentage ◽  
Unit Cell Size ◽  
Complex Shapes ◽  
Full Structure ◽  
Spherical Core

The paper aims to present the possibility of performing engineering calculations in domains of complex shapes expressed by mathematical descriptions. We focus on calculations done with the use of the Finite Element Method. An example of the compound structure is gyroid, which is a periodic structure representing an area close to the porous structure. The presented gyroid structure exhibits circular struts and a spherical core and spatially occupies a cube. The side length of the cube is defined as unit cell size, and the volume percentage of the struts inside the cube is referred to as volume fraction. The periodic cellular lattice structures are generated by our own software module. One of the uses of such structures is their employment in additive manufacturing (AM) of the so-called 3D printing (layer-by-layer AM technique), where they can contribute reducing the weight of an item and limiting the material consumption. It is important to answer the question of what effect does an element with a gyroid structure have on the thermal properties (e.g. the heat flow versus the volume fraction) compared to an element with full structure. The paper will show the results of such a comparison.

Low-Density Phenolic Syntactic Foams: Processing and Properties

2007 ◽  
Vol 26 (4) ◽  
pp. 229-244 ◽  
Author(s):  
Bibin John ◽  
C.P. Reghunadhan Nair ◽  
K.N. Ninan
Keyword(s):  
Phenolic Resin ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Mechanical Analysis ◽  
Low Density ◽  
Syntactic Foams ◽  
Novolac Resin ◽  
High Concentration ◽  
Volume Percentage ◽  
Propargyl Ether

Low-density phenolic syntactic foams with different volume percentages of microballoons were processed and their mechanical performance has been evaluated in terms of tensile, flexural, compressive and the corresponding specific properties. Tensile and flexural strength increased with volume fraction of microballoon and optimized at 72–74 percentage by volume of microballoon. Both the properties decreased with further addition of microballoon. The corresponding specific properties also manifested a similar order. Compressive and specific compressive strength decreased with increase in microballoon volume percentage. The flexural and compressive modulus values followed the same trend as the strength values. The properties of phenolic syntactic foams were compared with syntactic foams based on an addition cure phenolic resin, Propargyl Ether Novolac resin (PN). The mechanical properties of the latter were inferior to those of phenolic syntactic foams. The morphology of the failed samples as examined by SEM showed that failure occurred by a combination of matrix and microballoon failure at low microballoon loading whereas it occurred by microballoon cracking and resin to microballoon debonding at high concentration of filler. The dynamic mechanical analysis of phenolic and PN resin syntactic foams showed a higher use temperature for PN system in comparison to phenolic.

Experimental Analysis of Velocity Fields in Hot Extrusion of Aluminium Alloy 6351

2011 ◽  
Vol 491 ◽  
pp. 145-150 ◽  
Author(s):  
Marcelo Martins ◽  
Sérgio Tonini Button ◽  
José Divo Bressan
Keyword(s):  
Metal Forming ◽  
Internal Flow ◽  
Hot Extrusion ◽  
Experimental Tests ◽  
Velocity Fields ◽  
The Finite Element Method ◽  
Forming Process ◽  
Complex Shapes ◽  
Metal Forming Process ◽  
Volume Method

Hot extrusion is a metal forming process with a huge importance in the manufacturing of long metallic bars with complex shapes, and because of this, academics and industries are especially interested in better understanding how metal flows during the process. In order to have a reliable computational tool that can help to solve and to obtain material internal flow, experimental tests and numerical simulation with the finite element method were carried out to obtain results of the velocity fields generated in hot direct extrusion of aluminum billets (aluminum alloy 6351). The experimental results of the velocity field will be used to validate a computational code based on the finite volume method.

scholarly journals Digital printing of shape-morphing natural materials

2021 ◽  
Vol 118 (43) ◽  
pp. e2113715118
Author(s):  
Ze Zhao ◽  
Jatin Kumar ◽  
Youngkyu Hwang ◽  
Jingyu Deng ◽  
Mohammed Shahrudin Bin Ibrahim ◽  
...  
Keyword(s):  
Wide Spectrum ◽  
Substrate Material ◽  
Digital Printing ◽  
Shape Evolution ◽  
The Finite Element Method ◽  
Computational Simulations ◽  
Natural Materials ◽  
Shape Morphing ◽  
Geometrical Features ◽  
Complex Shapes

We demonstrate how programmable shape evolution and deformation can be induced in plant-based natural materials through standard digital printing technologies. With nonallergenic pollen paper as the substrate material, we show how specific geometrical features and architectures can be custom designed through digital printing of patterns to modulate hygrophobicity, geometry, and complex shapes. These autonomously hygromorphing configurations can be “frozen” by postprocessing coatings to meet the needs of a wide spectrum of uses and applications. Through computational simulations involving the finite element method and accompanying experiments, we develop quantitative insights and a general framework for creating complex shapes in eco-friendly natural materials with potential sustainable applications for scalable manufacturing.

The Effect of Grain Refiners for Aluminium Alloy Containing Mn-Ti-Sr Dispersoid

2006 ◽  
Vol 519-521 ◽  
pp. 449-454
Author(s):  
V.T. Vacariu ◽  
Aurelian Buzaianu ◽  
Eugeniu Vasile ◽  
R. Trusca ◽  
Petru Moldovan
Keyword(s):  
Volume Fraction ◽  
Lightweight Design ◽  
High Volume ◽  
Sr Modification ◽  
Fine Grain ◽  
Homogenization Time ◽  
Structural Applications ◽  
Complex Shapes ◽  
Metallic Compounds

The new structural applications of aluminum materials are determined by intelligent lightweight design: the demand of safety, ecology, recycling and by economics. Al-Si alloys allow complex shapes to be cast. Metallurgical a high volume fraction of fine dispersoid which are less about 0.1 microns in size are useful for retaining a fine grain. In the 6061 series of alloys, iron combines with aluminium and silicon to form two types of commune inter-metallic, (beta AlFeSi and alpha AlFeSi).The type of inter-metallic that is present these alloys will have an important bearing on the homogenization time, workability and quality of the surface finish. The microstructure of the as-cast samples was evaluated by electronic microscopy and the morphology of inter-metallic compounds related to the efficiently modification. Mn-Ti-Sr modification of Al-alloys is normally accompanied by an increase in porosity in the casting.

Transient Vibroacoustic Analysis of Functionally Graded Plates

2021 ◽  
pp. 1-36
Author(s):  
Avnish Mahendra Pandey ◽  
K. V. Nagendra Gopal
Keyword(s):  
Volume Fraction ◽  
Free Field ◽  
Shear Deformation Theory ◽  
Structural Response ◽  
Functionally Graded ◽  
Functionally Graded Plates ◽  
The Finite Element Method ◽  
Time Marching ◽  
The Time Domain ◽  
Vibroacoustic Response

Abstract This paper presents the vibroacoustic response of pure functionally graded plates under transient loading of mechanical nature. The functionally graded plate is modelled using the conventional first-order shear deformation theory to incorporate the effects of transverse shear and rotary inertia. The mid-surface variables are determined using the finite element method. Transient structural response is determined using Newmark Beta time marching scheme and the acoustic pressure in the free field is obtained using the time-domain Rayleigh integral. The effective material properties of the FG plate and the transient response of both the structural and acoustic fields have been computed in MATLAB. The influence of the volume fraction index, thickness ratio and boundary conditions of pure FG plate on its transient vibroacoustic response is investigated by a detailed parametric study.

The Effects of Layer-by-Layer Thickness and Fiber Volume Fraction Variation on the Mechanical Performance of a Pressure Vessel

2018 ◽  
Author(s):  
Emre Özaslan ◽  
Ali Yetgin ◽  
Volkan Coşkun ◽  
Bülent Acar ◽  
Tarık Olğar
Keyword(s):  
Finite Element ◽  
Layer Thickness ◽  
Pressure Vessel ◽  
Fiber Volume Fraction ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Element Model ◽  
Layer By Layer ◽  
Fiber Volume ◽  
Filament Wound

Due to high stiffness/weight ratio, composite materials are widely used in aerospace applications such as motor case of rockets which can be regarded as a pressure vessel. The most commonly used method to manufacture the pressure vessels is the wet filament winding. However, the mechanical performance of a filament wound pressure vessel directly depends on the manufacturing process, manufacturing site environmental condition and material properties of matrix and fiber. The designed ideal pressure vessel may not be manufactured because of the mentioned issues. Therefore, manufacturing of filament wound composite structures are based on manufacturing experience and experiment. In this study, the effect of layer-by-layer thickness and fiber volume fraction variation due to manufacturing process on the mechanical performance was investigated for filament wound pressure vessel with unequal dome openings. First, the finite element model was created for designed thickness dimensions and constant material properties for all layers. Then, the model was updated. The updated finite element model considered the layer-by-layer thickness and fiber volume fraction variation. Effects of the thickness and fiber volume fraction on the stress distribution along the motor axial direction were shown. Also hydrostatic pressurization test was performed to verify finite element analysis in terms of fiber direction strain through the motor case outer surface. Important aspects of analyzing a filament wound pressure vessel were addressed for designers.

EFFECT OF COOLING RATE ON THE TRANSITION TEMPERATURE IN Bi–Pb–Sr–Ca–Cu–O SYSTEM

1990 ◽  
Vol 04 (04) ◽  
pp. 293-299
Author(s):  
YUGUI WANG ◽  
JINSONG WANG ◽  
NANLIN WANG ◽  
XINPING JIAO ◽  
GUCHANG HAN ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Specific Heat ◽  
Cooling Rate ◽  
Volume Fraction ◽  
Oxygen Deficiency ◽  
Ac Susceptibility ◽  
Rapid Quenching ◽  
Nominal Composition ◽  
Unit Cell Size ◽  
Superconducting Volume Fraction

The resistance and ac susceptibility measurements show that cooling rate of the cast-annealing samples in heat treatment process has some effect on the 110 K superconducting phase in Bi–Pb–Sr–Ca–Cu–O system. Rapid quenching of the sample in air from 845°C causes oxygen deficiency in lattice and brings about a trifling change of unit cell size along c-axis direction. The dc magnetization and specific heat anomaly ∆c measurements demonstrate that fast cooling rate can reduce the transition temperature of high T c phase and the lower critical field, and weaken the pinning forces for vertex lines. The peak value of specific heat anomaly of the sample with nominal composition of Bi 1.7 Pb 0.3 Sr 2 Ca 2 Cu 4.5 O y is still small in comparison with YBa 2 Cu 3 O 7. From the magnetization curve we can estimate that the superconducting volume fraction is about 20%.

A Theoretical Formula for the Validity Limits of the Dipole Approximation for a Dielectric Mixture

2014 ◽  
Vol 906 ◽  
pp. 72-80
Author(s):  
Chang He Yang ◽  
Ding Long Cao ◽  
Lin Song Guo
Keyword(s):  
Finite Element Method ◽  
Numerical Solutions ◽  
Volume Fraction ◽  
Dipole Approximation ◽  
Empirical Method ◽  
Theoretical Formula ◽  
The Finite Element Method ◽  
Dielectric Mixture ◽  
Good Agreement ◽  
Dielectric Mismatch

A newly criterion for the validity limits of the dipole approximation for a dielectric mixture was presented, based on the comparison between the dipole approximation and the numerical solutions by the finite-element method (FEM). In terms of this criterion and the dipole-enhanced model, a simple theoretical formula for the validity limits was derived. This formula includes three variables: the dielectric mismatch, the volume fraction of particles and the precision. Its calculated results have a good agreement with the limits determined by the empirical method in the range of our interest, which indicates the theoretical formula is creditable. Using this formula, we can approximate the precision of the dipole approximation for an arbitrary dielectric mixture. And we found that the dipole approximation is acceptable with the precision equal to 30% when the dielectric mismatch is less than 2.3 (εi/ εe2.3) for the almost touching spheres.

INVESTIGATION OF Pt:MgO COMPOSITE FILMS PREPARED BY MAGNETRON SPUTTERING AND PULSED LASER CO-DEPOSITION METHOD

2019 ◽  
Vol 26 (07) ◽  
pp. 1850215
Author(s):  
J. Z. LOU ◽  
Y. S. ZHANG ◽  
X. H. DAI ◽  
J. M. SONG ◽  
Z. N. LI ◽  
...  
Keyword(s):  
Magnetron Sputtering ◽  
Composite Film ◽  
Volume Fraction ◽  
Composite Films ◽  
Pulsed Laser ◽  
Volume Ratio ◽  
X Ray Diffraction ◽  
Volume Percentage ◽  
Fraction Increase ◽  
Quartz Substrates

Pt:MgO composite films are prepared on quartz substrates at room temperature by magnetron sputtering and pulsed laser co-deposition (MSPLC) method, in which the volume ratio of the composite film can be easily controlled by MSPLC method. The sample with Pt volume percents of 40%, 50%, 60% and 70% are prepared, and all the samples are further annealed at 800∘C for 30[Formula: see text]min. Impacts of Pt content on the structural and physical properties have been investigated. Pt (111), (002) and (220) peaks can be observed, and the peak intensity increases with the increase of Pt content, as can be seen from the X-ray diffraction (XRD) pattern. Scanning electron microscope (SEM) results show that the size and density of grains increase and the distance between grains is decreased with the volume fraction increase. Significant absorption peaks were observed for different volume percentage of Pt:MgO composite film. Absorption peaks can be observed at 200, 220, 250 and 275[Formula: see text]nm, corresponding to Pt volume percents of 40%, 50%, 60% and 70%, respectively. The observed red shift of the absorption peak can be mainly related to the increase of Pt grain sizes.

The Effects of Layer-by-Layer Thickness and Fiber Volume Fraction Variation on the Mechanical Performance of a Pressure Vessel

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Emre Özaslan ◽  
Ali Yetgin ◽  
Bülent Acar ◽  
Volkan Coşkun ◽  
Tarık Olğar
Keyword(s):  
Finite Element ◽  
Pressure Vessel ◽  
Material Properties ◽  
Fiber Volume Fraction ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Element Model ◽  
Layer By Layer ◽  
Fiber Volume ◽  
Filament Wound

Abstract Due to high stiffness/weight ratio, composite materials are widely used in aerospace applications such as motor case of rockets which can be regarded as a pressure vessel. The most commonly used method to manufacture pressure vessels is the wet filament winding. However, the mechanical performance of a filament wound pressure vessel directly depends on the manufacturing process, manufacturing site environmental condition, and material properties of matrix and fiber. The designed pressure vessel may not be manufactured because of the mentioned issues. Therefore, manufacturing of filament wound composite structures are based on manufacturing experience and experiment. In this study, effects of layer-by-layer thickness and fiber volume fraction variation due to manufacturing process on the mechanical performance were investigated for filament wound pressure vessel with unequal dome openings. First, the finite element model was created for designed thickness dimensions and constant material properties for all layers. Then, the model was updated. The updated finite element model considered the thickness of each layer separately and variation of fiber volume fraction between the layers. Effects of the thickness and fiber volume fraction on the stress distribution along the motor axial direction were shown. Also hydrostatic pressurization tests were performed to verify finite element analysis in terms of fiber direction strain through the motor case outer surface. Important aspects of analyzing a filament wound pressure vessel were addressed for designers.

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