scholarly journals Non-Symmetrical Direct Extrusion—Analytical Modelling, Numerical Simulation and Experiment

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7856
Author(s):  
Marek Kowalik ◽  
Piotr Paszta ◽  
Tomasz Trzepieciński ◽  
Leon Kukiełka
Keyword(s):  
Finite Element ◽  
Experimental Studies ◽  
Experimental Tests ◽  
Radius Of Curvature ◽  
Curvature Radius ◽  
Outer Diameter ◽  
Extrusion Die ◽  
Curved Pipes ◽  
Lead Pipes ◽  
Simulation And Experiment

The article presents the original technology of the extrusion of hollow curved pipes. The curvature radius of pipe axis was obtained directly during extrusion by eccentric alignment of the annular calibration gap of the extrusion die. Theoretical relationships describing the radius of curvature of the extruded part as a function of the eccentricity e of position of the annular calibration gap in the die were developed. A die with replaceable inserts with eccentricity e equal to 1, 2, 3, 5, 7 mm was designed and fabricated. Experimental tests were carried out to extrude lead pipes with an outer diameter of 20 mm and an inner diameter of 18 mm. Measurements of the radii of the curvature of the extruded pipes were consistent with the values calculated from the developed theoretical relationships. Numerical modelling of the proposed method of extrusion in a finite element-based QForm 3D program was carried out. The finite element method (FEM) numerical calculations were carried out for lead. Numerical simulations and experimental studies have shown that, by changing the value of the eccentric gap, the radius of curvature of the extruded pipe can be controlled.

Experimental and numerical analysis of vibration frequency in sandwich composites with different radii of curvature

2017 ◽  
Vol 21 (8) ◽  
pp. 2870-2886
Author(s):  
Melis Yurddaskal ◽  
Buket Okutan Baba
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Boundary Conditions ◽  
Natural Frequencies ◽  
Experimental Studies ◽  
Sandwich Panels ◽  
Mode Shapes ◽  
Sandwich Composite ◽  
Radius Of Curvature ◽  
Finite Element Software

In this study, free vibration responses of sandwich composite panels with different radius of curvature were presented numerically. The studies were carried out on square flat and curved sandwich panels made of E-glass/epoxy face sheets and polyvinyl chloride foam with three different radii of curvature. Experimental studies were used to verify the numerical results. Vibration tests were performed on flat and curved sandwich panels under free–free boundary conditions. The experimental data were then compared with finite element simulation, which was conducted by ANSYS finite element software and it was shown that the numerical analysis results agree well with the experimental ones. Effect of the curvature on natural frequencies under different boundary conditions (all edge free, simply supported, and fully clamped) was investigated numerically. Results indicated that the natural frequencies and corresponding mode shapes were affected by boundary conditions and curvature of the panel. For all boundary conditions, the variation of curvature had smaller effect on the natural frequency of the first mode than those of the other modes.

Novel U-bending designed setups for investigating the spring-back/spring-go of two-layer aluminum/copper sheets through experimental tests and finite element simulations

2020 ◽  
Vol 234 (8) ◽  
pp. 1142-1153 ◽  
Author(s):  
Ehsan Etemadi ◽  
Abbas Naseri ◽  
Mohsen Valinezhad
Keyword(s):  
Finite Element ◽  
Experimental Tests ◽  
Finite Element Simulations ◽  
Curvature Radius ◽  
Stacking Sequence ◽  
Spring Back ◽  
Effective Parameters ◽  
Bending Process ◽  
Copper Aluminum ◽  
Good Agreement

This paper presents novel U-bending setups in order to investigate the effects of the curvatures created on the punch, die, or both on the spring-back/spring-go of the two-layer aluminum/copper sheets. Comparison of the new U-bending setups with the regular ones showed that the curvatures had important roles in reducing the spring-back/spring-go in the U-bending process. The results further indicated the good agreement between spring-back/spring-go and finite element simulations. Moreover, through finite element simulations, the effects of three effective parameters on reducing the spring-back/spring-go, including the curvature radius ( r) of the punch, the distance between curvature center and the fillet center ( d) in the punch, and the curvature radius at the end of the die ( R) were investigated. In achieving the desired state (90°), the results showed that the distance of curvature center from the fillet center ( d) was a more important parameter compared with the curvature radius at the end of the punch ( r) and the curvature radius at the end of the die ( R). This paper also focuses on the thicknesses of copper and aluminum as well as the stacking sequence of layers. Concerning the thicknesses of the implemented copper and aluminum change, the minimum angle of the spring-back/spring-go relative to the desired state was 75% Al/25% Cu thickness. Furthermore, the spring-back of aluminum/copper was lower than the copper/aluminum layer sheet. The effects of both thickness changing and stacking sequence of aluminum/copper layers on the spring-back/spring-go amounts of different sheets were due to the relocation of the neutral axis.

scholarly journals Effects of the Radius of Curvature on Natural Frequency and Mode Shape

2019 ◽  
Vol 7 (12) ◽  
Author(s):  
Can Gonenli ◽  
Hasan Ozturk ◽  
Oguzhan Das
Keyword(s):  
Finite Element ◽  
Natural Frequency ◽  
Natural Frequencies ◽  
Free Vibration Analysis ◽  
Mode Shapes ◽  
Radius Of Curvature ◽  
Curvature Radius ◽  
Finite Element Program ◽  
Plane Theory ◽  
Element Type

In this study, the effect of radius of curvature on the natural frequency of isotropic square thin plate is investigated. The models examined are obtained by simply changing the radius of curvature by keeping the length constant from the flat plate to the semicircle model. The free vibration analysis of the plates fixed on two straight edges is performed by the finite element method. As a finite element type, the four-node quadrilateral rectangular element type, which has a total of 24 generalized coordinates, is used. Out-of-plane theory and in-plane theory are used together to form the curve model. The accuracy and validity of the theory are controlled with the data obtained from the finite element program. The effect of the curvature radius on the first five natural frequencies and the mode shapes of these natural frequencies is given in tables and graphs.

Research on the Seismic Response Characteristic under Different Curvature Radios

2011 ◽  
Vol 243-249 ◽  
pp. 536-540
Author(s):  
Qing Ning Li ◽  
Feng Jie Jiang ◽  
Tian Li Wang ◽  
Jian Pen Sun ◽  
Lei Juan Wang
Keyword(s):  
Finite Element ◽  
Response Spectrum ◽  
Dynamic Performance ◽  
Single Point ◽  
Time History ◽  
Response Characteristic ◽  
Radius Of Curvature ◽  
Curvature Radius ◽  
Seismic Action ◽  
Finite Element Program

The curvature radius is a very important factor which influences the dynamic performance of the curved continuous long bridge badly. This paper based on the practical engineering, with large finite element program, established the curved continuous long bridge space finite element calculation model. Respectively by response spectrum method and the time-history response method, consider single-point excitation and multi-support excitation seismic action, Analyzes different radius of curvature in curved continuous long bridge self-vibration frequency, internal force and displacement on the differences, and given the internal relations between the difference and the curvature radius, offer some reasonable design reference suggestion for curved continuous long bridge of the radius of curvature.

HotPipe JI Project: Experimental Test and FE Analyses

2005 ◽  
Author(s):  
Luigino Vitali ◽  
Lorenzo Bartolini ◽  
Dag Askheim ◽  
Ralf Peek ◽  
Erik Levold
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Internal Pressure ◽  
Phase 1 ◽  
Local Buckling ◽  
Experimental Tests ◽  
Element Model ◽  
Thickness Ratio ◽  
Outer Diameter ◽  
Test Configuration

In the last twenty years, experimental tests and FEM-based theoretical studies have been carried out to investigate the buckling mechanisms of thin-walled pipes subject to internal pressure, axial force and bending moment. Unfortunately, these studies do not completely cover the scope relevant for offshore pipelines i.e. outer diameter to thickness ratio lower than 50. In the HotPipe Phase 2 JI Project, full-scale bending tests were performed on pressurized pipes to verify the Finite Element Model predictions from HotPipe Phase 1 of the beneficial effect of internal pressure on the capacity of pipes to undergo large plastic bending deformations without developing local buckling. A total of 4 pipes were tested, the key test parameters being the outer-diameter-to-wall-thickness ratio (seameless pipes with D/t = 25.6, and welded UOE pipes with D/t = 34.2), and the presence of a girth weld in the test section. For comparison a Finite Element Model was developed with shell elements in ABAQUS. The test conditions were matched as closely as possible: this includes the test configuration, the stress-strain curves (i.e. using measured curves as input), and the loading history. The FE results very realistically reproduce the observed failure mechanisms by formation and localization of wrinkles on the compression side of the pipe. Good agreement is also achieved in the moment capacities (with predictions only 2.5 to 8% above measured values), but larger differences arose for the deformation capacity, suggesting that the DNV OS-F101 formulation for the characteristic bending strain (which is based on FE predictions from HotPipe Phase I) may be non-conservative in certain cases.

Experimental Studies Concerning the Semipermeable Membrane Separation Efficiency for 134Cs, 137Cs, 57Co, 58Co, 60Co, 54Mn in Liquid Radioactive Waste I. Treatment of secondary waste from POD decontamination procedure

2008 ◽  
Vol 59 (5) ◽  
Author(s):  
Mirela Dulama ◽  
Nicoleta Deneanu ◽  
Cristian Dulama ◽  
Margarit Pavelescu
Keyword(s):  
Membrane Separation ◽  
Separation Efficiency ◽  
Liquid Radioactive Waste ◽  
Experimental Studies ◽  
Experimental Tests ◽  
Suspended Solid ◽  
Process Efficiency ◽  
Active Charcoal ◽  
Precipitation Process ◽  
Pre Treatment

The paper presents the experimental tests concerning the treatment by membrane techniques of radioactive aqueous waste. Solutions, which have been treated by using the bench-scale installation, were radioactive simulated secondary wastes from the decontamination process with modified POD. Generally, an increasing of the retention is observed for most of the contaminants in the reverse osmosis experiments with pre-treatment steps. The main reason for taking a chemical treatment approach was to selectively remove soluble contaminants from the waste. In the optimization part of the precipitation step, several precipitation processes were compared. Based on this comparison, mixed [Fe(CN)6]4-/Al3+/Fe2+ was selected as a precipitation process applicable for precipitation of radionuclides and flocculation of suspended solid. Increased efficiencies for cesium radionuclides removal were obtained in natural zeolite adsorption pre-treatment stages and this was due to the fact that volcanic tuff used has a special affinity for this element. Usually, the addition of powdered active charcoal serves as an advanced purifying method used to remove organic compounds and residual radionuclides; thus by analyzing the experimental data (for POD wastes) one can observe a decreasing of about 50% for cobalt isotopes subsequently to the active charcoal adsorption.. The semipermeable membranes were used, which were prepared by the researchers from the Research Center for Macromolecular Materials and Membranes, Bucharest. The process efficiency was monitored by gamma spectrometry.

scholarly journals Experimental and Numerical Investigation on the Perforation Resistance of Double-Layered Metal Shield under High-Velocity Impact of Armor-Piercing Projectiles

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 626
Author(s):  
Riccardo Scazzosi ◽  
Marco Giglio ◽  
Andrea Manes
Keyword(s):  
High Strength Steel ◽  
Steel Plate ◽  
Experimental Studies ◽  
Practical Interest ◽  
High Strength ◽  
Experimental Tests ◽  
Element Model ◽  
Transportation Systems ◽  
Metal Shield ◽  
Softening Parameter

In the case of protection of transportation systems, the optimization of the shield is of practical interest to reduce the weight of such components and thus increase the payload or reduce the fuel consumption. As far as metal shields are concerned, some investigations based on numerical simulations showed that a multi-layered configuration made of layers of different metals could be a promising solution to reduce the weight of the shield. However, only a few experimental studies on this subject are available. The aim of this study is therefore to discuss whether or not a monolithic shield can be substituted by a double-layered configuration manufactured from two different metals and if such a configuration can guarantee the same perforation resistance at a lower weight. In order to answer this question, the performance of a ballistic shield constituted of a layer of high-strength steel and a layer of an aluminum alloy impacted by an armor piercing projectile was investigated in experimental tests. Furthermore, an axisymmetric finite element model was developed. The effect of the strain rate hardening parameter C and the thermal softening parameter m of the Johnson–Cook constitutive model was investigated. The numerical model was used to understand the perforation process and the energy dissipation mechanism inside the target. It was found that if the high-strength steel plate is used as a front layer, the specific ballistic energy increases by 54% with respect to the monolithic high-strength steel plate. On the other hand, the specific ballistic energy decreases if the aluminum plate is used as the front layer.

scholarly journals Thermal Inertia Characterization of Multilayer Lightweight Walls: Numerical Analysis and Experimental Validation

2021 ◽  
Vol 11 (11) ◽  
pp. 5008
Author(s):  
Juan José del Coz-Díaz ◽  
Felipe Pedro Álvarez-Rabanal ◽  
Mar Alonso-Martínez ◽  
Juan Enrique Martínez-Martínez
Keyword(s):  
Lightweight Concrete ◽  
Thermal Flux ◽  
Experimental Studies ◽  
Thermal Inertia ◽  
Transient State ◽  
Experimental Tests ◽  
Building Design ◽  
Experimental Methodology ◽  
Improve Energy Efficiency ◽  
Concrete Blocks

The thermal inertia properties of construction elements have gained a great deal of importance in building design over the last few years. Many investigations have shown that this is the key factor to improve energy efficiency and obtain optimal comfort conditions in buildings. However, experimental tests are expensive and time consuming and the development of new products requires shorter analysis times. In this sense, the goal of this research is to analyze the thermal behavior of a wall made up of lightweight concrete blocks covered with layers of insulating materials in steady- and transient-state conditions. For this, numerical and experimental studies were done, taking outdoor temperature and relative humidity as a function of time into account. Furthermore, multi-criteria optimization based on the design of the experimental methodology is used to minimize errors in thermal material properties and to understand the main parameters that influence the numerical simulation of thermal inertia. Numerical Finite Element Models (FEM) will take conduction, convection and radiation phenomena in the recesses of lightweight concrete blocks into account, as well as the film conditions established in the UNE-EN ISO 6946 standard. Finally, the numerical ISO-13786 standard and the experimental results are compared in terms of wall thermal transmittance, thermal flux, and temperature evolution, as well as the dynamic thermal inertia parameters, showing a good agreement in some cases, allowing builders, architects, and engineers to develop new construction elements in a short time with the new proposed methodology.

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