scholarly journals Folded Sheets as a Universal Material for Shaping Transformed Shell Roofs

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2051
Author(s):  
Jacek Abramczyk
Keyword(s):  
Computer Simulations ◽  
Constitutive Relations ◽  
Experimental Tests ◽  
Ruled Surfaces ◽  
Complex State ◽  
Geometric Properties ◽  
Building Roof ◽  
Characteristic Lines ◽  
Roof Shells ◽  
Insight Into

This article provides a novel insight into specific properties of flat folded sheets transformed elastically into building roof shells. Elastic twist transformations of the sheets resulting from the arrangement of the sheets on two skew roof directrices cause changes in the geometric and mechanical sheet properties of the roof shell sheeting composed of these sheets. Regular smooth-ruled surfaces and their characteristic lines are used in the analysis of changes in the geometric properties. In the analysis of the mechanical changes, the constitutive relations and complex state of stresses are considered. The analysis is carried out on the basis of the results of the experimental tests and FEM computer simulations. They have led to the development of such a method of shaping of the effectively transformed folded covers that ensures the initial effort of each shell fold to be the smallest possible.

A Study on Polymer Particle Flow in a Disk Zone of a Screw-Disk Extruder

2014 ◽  
Vol 35 (1) ◽  
pp. 121-135 ◽  
Author(s):  
Tomasz Rydzkowski ◽  
Iwona Michalska-Pożoga
Keyword(s):  
Mechanical Properties ◽  
Computer Simulations ◽  
Particle Motion ◽  
Polymer Melt ◽  
Experimental Tests ◽  
Polymer Particle ◽  
Particle Flow ◽  
Material Particle ◽  
Motion Trajectories ◽  
Stretching Effect

Abstract The paper presents the summary of research on polymer melt particle motion trajectories in a disc zone of a screw-disk extruder. We analysed two models of its structure, different in levels of taken simplifications. The analysis includes computer simulations of material particle flow and results of experimental tests to determine the properties of the resultant extrudate. Analysis of the results shows that the motion of melt in the disk zone of a screw-disk extruder is a superposition of pressure and dragged streams. The observed trajectories of polymer particles and relations of mechanical properties and elongation of the molecular chain proved the presence of a stretching effect on polymer molecular chains.

Experimental tests of constitutive relations for polymers undergoing uniaxial shear flows

1977 ◽  
Vol 16 (3) ◽  
pp. 291-301 ◽  
Author(s):  
W. W. Graessley ◽  
W. S. Park ◽  
R. L. Crawley
Keyword(s):  
Shear Flows ◽  
Constitutive Relations ◽  
Experimental Tests

scholarly journals FEM Study of a Steel Corrugated Web Plate Girder Subjected to Fire

2021 ◽  
Vol 26 (2) ◽  
pp. 201-218
Author(s):  
D. Sokołowski ◽  
M. Kamiński
Keyword(s):  
High Strength Steel ◽  
Constitutive Relations ◽  
High Strength ◽  
Experimental Tests ◽  
Physical Parameters ◽  
Bottom Flange ◽  
Gas Temperature ◽  
Temperature Dependent ◽  
Corrugated Web ◽  
Plate Girder

Abstract The main aim of this work is a computational nonlinear analysis of a high strength steel corrugated-web plate girder with a very detailed and realistic mesh including vertical ribs, all the fillet welds and supporting areas. The analysis is carried out to verify mechanical structural response under transient fire temperature conditions accounting for an efficiency and accuracy of three various transient coupled thermo-elastic models. All the resulting stress distributions, deformation modes and their time variations, critical loads and eigenfrequencies as well as failure times are compared in all these models. Nonlinearities include material, geometrical and contact phenomena up to the temperature fluctuations together with temperature-dependent constitutive relations for high strength steel. They result partially from steady state and transient experimental tests or from the additional designing rules included in Eurocodes. A fire scenario includes an application of the normative fire gas temperature curve on the bottom flange of the entire girder for a period of 180 minutes. It is computed using sequentially coupled thermo-elastic Finite Element Method analyses. These account for heat conductivity, radiation and convection. The FEM model consists of a combination of 3D hexahedral and tetrahedral solid finite elements and uses temperature-dependent material and physical parameters, whose values are taken after the experiments presented in Eurocodes. Numerical results presented here demonstrate a fundamental role of the lower flange in carrying fire loads according to this scenario and show a contribution of the ribs and of the welds to the strength of the entire structure.

Spontane Taaldata en het Meten van Lexicale RIJKDOM I Tweede-taalverwerving

1988 ◽  
Vol 30 ◽  
pp. 67-80 ◽  
Author(s):  
Roeland van Hout ◽  
Anne Vermeer
Keyword(s):  
Second Language ◽  
Language Learners ◽  
Computer Simulations ◽  
Second Language Learners ◽  
Simple Computer ◽  
Spoken Text ◽  
Text Corpora ◽  
Lexical Richness ◽  
Speech Data ◽  
Insight Into

Increasing use of spontaneous speech data in second language re-search made it necessary to use other measures than tests for getting insight into the lexical richness of (spoken) text corpora of second language learners. In this article several lexical measures (types, TTR(c), Guiraud, logTTR, Uber, theoretical vocabulary) are examined and discussed. On the basis of several studies that the TTR is the worst measure possible, but the better measures (types, Guiraud, theoretical vocabulary) are problematic too. Next, the characteristics of the lexical measures are examined by means of a few simple computer simulations with hypothetical lexica. The outcome is mat neither the reliability, nor the validity of the different measures are satisfactory, especially with respect to the TTR.

Experimental and empirical study of large transverse deformation of triangular plates subjected to water hammer shock loading

2019 ◽  
Vol 233 (12) ◽  
pp. 2498-2509
Author(s):  
Mojtaba Haghgoo ◽  
Mohammad Rezasefat ◽  
Ali Mahmoudi ◽  
Hashem Babaei
Keyword(s):  
Mechanical Properties ◽  
Center Of Mass ◽  
Experimental Tests ◽  
Experimental Results ◽  
Dimensionless Numbers ◽  
Hydrodynamic Loads ◽  
Drop Hammer ◽  
Properties Of Materials ◽  
Plate Geometry ◽  
Insight Into

In this paper, the dynamic plastic response of isosceles triangular plates under hydrodynamic loads was investigated experimentally using a drop hammer machine. To do this, a series of experimental tests were carried out on mild steel triangular plates with different thicknesses to bring insight into the effect of geometry and mechanical properties of the plate on the deformation of specimens, which were impacted by a piston-induced pressure wave inside a water tube. The effects of various impact loads originated from different drop hammer standoff distances, and hammer weights concerning variations of deflection of the center of mass were described. The experimental results were presented in terms of deflection of the center of mass of the plates and deflection profiles. The experimental results showed that the plate with lower thickness experienced higher deflection-to-thickness ratio. An empirical model was also proposed based on new dimensionless numbers for triangular plates in order to predict the ratio of deflection of the center of mass to thickness. The dimensionless numbers considered the effects of plate geometry, hydrodynamic applied load, and mechanical properties of materials. Comparison between the experimental results and empirical predictions demonstrated that the suggested model is accurate enough to predict of the response of isosceles triangular plates under hydrodynamic loads.

Adiabatic Shear Localization in a Liquid Lubricant Under Pressure

1994 ◽  
Vol 116 (4) ◽  
pp. 705-708 ◽  
Author(s):  
Scott Bair ◽  
Farrukh Qureshi ◽  
Michael Khonsari
Keyword(s):  
Energy Equation ◽  
Shear Bands ◽  
Experimental Tests ◽  
Valuable Insight ◽  
Rapid Rise ◽  
Brinkman Number ◽  
Liquid Lubricant ◽  
Elevated Pressures ◽  
Insight Into ◽  
Unstable Temperature

Experimental tests with a high-pressure flow visualization cell clearly reveal that the shear deformation in a lubricant film at elevated pressures can localize by a mechanism vastly different from previously reported mechanically-induced shear bands. Verification by numerical solution of the energy equation shows that for a stress-controlled experiment, provided that the Brinkman number is sufficiently large, the local temperature experiences a rapid rise. The rapid rise of temperature along with the local rate of shear favors an unstable temperature profile. The research provides valuable insight into the behavior of lubricants under extreme conditions since this phenomenon may be operating in the thermally dominated regime of EHD traction. Furthermore, the fact that the hot shear band is isolated from the metal boundaries by a cooler liquid, may confound recent attempts to infer the shear stress distribution in a concentrated contact from IR temperature measurement of the metal temperature distribution.

scholarly journals Probing Shells Against Buckling: A Nondestructive Technique for Laboratory Testing

2017 ◽  
Vol 27 (14) ◽  
pp. 1730048 ◽  
Author(s):  
J. Michael T. Thompson ◽  
John W. Hutchinson ◽  
Jan Sieber
Keyword(s):  
Lateral Displacement ◽  
Experimental Tests ◽  
Volume Control ◽  
Imperfection Sensitivity ◽  
Nondestructive Technique ◽  
Experimental Procedure ◽  
Buckling Behavior ◽  
Highly Nonlinear ◽  
Structural Specimen ◽  
Insight Into

This paper addresses testing of compressed structures, such as shells, that exhibit catastrophic buckling and notorious imperfection sensitivity. The central concept is the probing of a loaded structural specimen by a controlled lateral displacement to gain quantitative insight into its buckling behavior and to measure the energy barrier against buckling. This can provide design information about a structure’s stiffness and robustness against buckling in terms of energy and force landscapes. Developments in this area are relatively new but have proceeded rapidly with encouraging progress. Recent experimental tests on uniformly compressed spherical shells, and axially loaded cylinders, show excellent agreement with theoretical solutions. The probing technique could be a valuable experimental procedure for testing prototype structures, but before it can be used a range of potential problems must be examined and solved. The probing response is highly nonlinear and a variety of complications can occur. Here, we make a careful assessment of unexpected limit points and bifurcations, that could accompany probing, causing complications and possibly even collapse of a test specimen. First, a limit point in the probe displacement (associated with a cusp instability and fold) can result in dynamic buckling as probing progresses, as demonstrated in the buckling of a spherical shell under volume control. Second, various types of bifurcations which can occur on the probing path which result in the probing response becoming unstable are also discussed. To overcome these problems, we outline the extra controls over the entire structure that may be needed to stabilize the response.

Insight Into the Design of Blast-Mitigating Floor Mats Using Design of Experiments

2019 ◽  
Author(s):  
Hisham Kamel
Keyword(s):  
Design Of Experiments ◽  
Computational Study ◽  
Close Contact ◽  
Dynamic Performance ◽  
Experimental Tests ◽  
Element Model ◽  
Influential Factor ◽  
Fe Model ◽  
Energy Absorbing ◽  
Insight Into

Abstract Recently, Improvised explosive devices (IEDs) have evolved into a major and significant threat inflicting substantial human casualties and property damage. The majority of injuries are to the lower extremities since they are in close contact to vehicle floor. Floor mats have been developed to mitigate the effects of IEDs blasts. This paper reports a computational study on the energy absorbing behavior of a novel commercial floor mat — Skydex — for foot protection. The design of experiments (DOE) approach was applied to investigate the effect of shape variations on the dynamic performance of a finite element model of Skydex. The FE model was verified using experimental tests on samples produced using 3D printing technique. The DOE approach revealed significant insight into the design of Skydex. It confirmed that shape variables have strong effect on the amount of energy absorbed and the transmitted load. DOE specifically identified the radius of the mid-section of Skydex as the most influential factor in controlling the mode of deformation under compression. In addition, it uncovered the interaction effect between the radius of curvatures of the two hemispheres and upper and lower radii. Finally, DOE revealed the bi-trade-off relations between energy absorbed, transmitted load and mass. These were shown in meaningful and helpful plots which will help the development of Skydex design.

scholarly journals AC/DC Current Sensor for Rotating Applications

Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6811
Author(s):  
Miguel Angel Pardo-Vicente ◽  
Carlos A. Platero ◽  
José Ángel Sánchez-Fernández ◽  
Francisco Blázquez
Keyword(s):  
Computer Simulations ◽  
Direct Current ◽  
Electromagnetic Coupling ◽  
Experimental Tests ◽  
Signal Amplitude ◽  
Current Measurement ◽  
Current Sensor ◽  
External Fields ◽  
Large Size ◽  
Dc Current

There are several techniques for current measurement. Most of them are capable of measuring both alternating and direct current (AC/DC) components. However, they have severe drawbacks for rotating applications (large size, sensitivity to external fields, and low signal amplitude). In addition to these weaknesses, measured signals should be transmitted to a stationary part. In order to contribute solving these difficulties, this paper presents a sensor that can measure AC/DC simultaneously based on the electromagnetic coupling of two coils. To this aim, the measured waveform is analysed. In this paper, the design of such a sensor is presented. This design is validated through computer simulations and a prototype is built. The performance of this sensor prototype is analysed through experimental tests.

scholarly journals Understanding and Controlling Food Protein Structure and Function in Foods: Perspectives from Experiments and Computer Simulations

2020 ◽  
Vol 11 (1) ◽  
pp. 365-387 ◽  
Author(s):  
Fernando Luís Barroso da Silva ◽  
Paolo Carloni ◽  
David Cheung ◽  
Grazia Cottone ◽  
Serena Donnini ◽  
...  
Keyword(s):  
Computer Simulations ◽  
Critical Role ◽  
Pharmaceutical Products ◽  
Food Protein ◽  
Combining Data ◽  
In Silico Modeling ◽  
Physiological Outcomes ◽  
And Function ◽  
And Control ◽  
Insight Into

The structure and interactions of proteins play a critical role in determining the quality attributes of many foods, beverages, and pharmaceutical products. Incorporating a multiscale understanding of the structure–function relationships of proteins can provide greater insight into, and control of, the relevant processes at play. Combining data from experimental measurements, human sensory panels, and computer simulations through machine learning allows the construction of statistical models relating nanoscale properties of proteins to the physicochemical properties, physiological outcomes, and tastes of foods. This review highlights several examples of advanced computer simulations at molecular, mesoscale, and multiscale levels that shed light on the mechanisms at play in foods, thereby facilitating their control. It includes a practical simulation toolbox for those new to in silico modeling.

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