Numerical simulation of dynamic pressures on a novel drafting system and experimental study on yarn properties based on friction fields

2021 ◽  
pp. 004051752110460
Author(s):  
Jing Quan ◽  
Longdi Cheng ◽  
Jianyong Yu ◽  
Wenliang Xue
Keyword(s):  
Numerical Simulation ◽  
Pressure Distribution ◽  
Friction Force ◽  
Dynamic Pressure ◽  
Experimental Studies ◽  
The Novel ◽  
Friction Forces ◽  
Pressure Distributions ◽  
Significant Difference ◽  
Pressure Peak

The friction fields of a novel drafting device based on the ring spinning frame are investigated in terms of numerical simulation and experimental studies. In numerical simulation, the results demonstrate that the dynamic pressure distribution in the drafting zone is presented in the form of wave undulation in the main drafting zone. Besides this, the pressure peak greatly increases close to the front nip. The effect of different spacers and middle roller speeds on the pressure distribution was also simulated, which indicates that the dynamic pressure decreases strictly with increasing spacer size, while at middle roller speeds of 0.18 rad/s and 0.26 rad/s the pressure distributions only show a significant difference at the pins nip and not throughout the drafting zone. For experimental studies, the friction fields of the novel drafting device were tested with different spacers. The peaks of the friction field decrease with the increasing spacing in the main drafting zone. The friction force shows a wavy undulation in the direction of the middle roller nip to the front roller nip, and there is also a great increase in the peak of the friction force near the front roller nip. Analysis of the properties of the three yarns spun by the novel draft device under different spacers shows that changing the spacer affects the friction forces of the drafting zone and has a significant effect on the yarn evenness, imperfections, and strength, but not on the hairiness.

Study of the Pressure Distribution between the Piston Rings in Reciprocating Compressors

2011 ◽  
Vol 383-390 ◽  
pp. 6048-6052
Author(s):  
Dian Bo Xin ◽  
Jian Mei Feng ◽  
Yan Jing Xu ◽  
Xue Yuan Peng
Keyword(s):  
Pressure Distribution ◽  
Piston Ring ◽  
Dynamic Pressure ◽  
Threshold Value ◽  
Piston Rings ◽  
Premature Failure ◽  
Root Cause ◽  
Pressure Distributions ◽  
Start Up ◽  
Set Up

Piston ring is one of the most important sealing components that can be easily damaged in reciprocating compressors. The severe non-uniformity of the pressure distribution was suggested to be the essential reason for the premature failure of the piston rings. Therefore, a test rig was set up to measure the pressure distributions as well as the build-up of the dynamic pressure difference, which could reveal the root cause for the non-uniformity of the pressure distributions. The results showed that the build-ups of the pressure differences between different rings were not simultaneous; there existed a threshold pressure, and the latter ring could work only when the pressure before the former ring reached to the threshold value. The pressure distributions were also investigated at the start-up and shut-down of the compressor, which further validated the cause of the premature failure of the first ring.

Elastic-Plastic Partial Slip Rolling Wheel-Rail Contact With an Oblique Rail Crack

2004 ◽  
Author(s):  
Yung-Chuan Chen ◽  
Jao-Hwa Kuang
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Friction Force ◽  
Element Model ◽  
Partial Slip ◽  
Contact Pressure Distribution ◽  
Tractive Force ◽  
Plastic Energy ◽  
Elastic Plastic ◽  
Pressure Distributions

The effect of rail surface crack on the wheel-rail contact pressure distribution under partial slip rolling was studied in this work. The elastic-plastic finite element model was employed for stress analyses. The numerical simulations were used to explore the effects of the contact distances and tractive force on the normal and tangential contact pressure distributions, tip plastic energy and critical wheel applied load. Contact elements were used to simulate the interaction between wheel and rail and crack surfaces. Numerical results indicate that the contact pressure distributions are significantly affected by the rail crack. Traditional contact theories are not available to describe the contact pressure distribution on the contact crack surfaces. Results also indicate that a higher friction force on the contact crack surfaces is observed for wheel subjected a larger tractive force. A larger crack surfaces friction force can reduce the sliding between crack surfaces and leads to a smaller tip plastic energy.

Two-Dimensional Contact Pressure Distribution of a Radial Tire

1990 ◽  
Vol 18 (2) ◽  
pp. 80-103 ◽  
Author(s):  
T. Akasaka ◽  
M. Katoh ◽  
S. Nihei ◽  
M. Hiraiwa
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Side Wall ◽  
Bending Moment ◽  
Two Dimensional ◽  
Contact Pressure Distribution ◽  
Friction Forces ◽  
Radial Tire ◽  
Pressure Distributions ◽  
Reaction Forces

Abstract Two-dimensional contact pressure distribution of a radial tire, statically compressed to a flat roadway, is analyzed using a rectangular contact patch. The tire structure is modeled by a spring-bedded ring belt comprised of a laminated-biased composite strip. The belt is supported by radial springs simulating the sidewall. The spring constant Kr was well defined previously by one of the authors. Deformation of the rectangular flat belt is obtained theoretically. The belt is subjected to inflation pressure, reaction forces transmitted from the spring bed of the tread rubber, and shearing force and bending moment along the belt boundaries brought from side-wall springs and the detached part of the ring belt. In-plane membrane forces, which are not uniform in the contact area, due to the friction forces acting between the tread surface and the roadway are also applied. The resulting contact pressure distributions in the circumferential direction are shown to be convex along the shoulder, but concave along the crown center line. This distribution agrees well with the experimental results.

Numerical Simulation of Wind Pressure on Different Types of Large-Span Roofs

2012 ◽  
Vol 170-173 ◽  
pp. 3371-3374
Author(s):  
Ying Jia ◽  
Xi Meng ◽  
Hai Jun Zhang
Keyword(s):  
Numerical Simulation ◽  
Pressure Distribution ◽  
Wind Direction ◽  
Influencing Factor ◽  
Wind Pressure ◽  
Large Span ◽  
Computing Platform ◽  
Pressure Distributions ◽  
Roof Shape ◽  
Main Factor

The geometric shape of buildings in wind field is an important influencing factor of wind pressure distribution on the buildings. Along with the change of roof shape, wind pressure distributions vary obviously. In this paper, the numerical simulation of the wind pressure for four types of large-span roofs is carried out, using CFX12.0 as computing platform. The characteristics of wind pressure distribution are studied by considering some parameters, such as wind direction, rise-span ratio, and terrain roughness. Wind pressure distribution is greatly affected by wind direction, and the wind pressure on large-span roofs is dominated by suction; the vortex shedding produced by airflow separation is the main factor affecting the characteristics of wind load.

Improvement Of Curvilinear Diagrams Of Concrete Deformation

2019 ◽  
pp. 99-104
Keyword(s):  
Reinforced Concrete ◽  
Peak Load ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
Significant Difference ◽  
Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

One-Dimensional Contact Pressure Distribution of Radial Tires in Motion

1995 ◽  
Vol 23 (2) ◽  
pp. 116-135 ◽  
Author(s):  
H. Shiobara ◽  
T. Akasaka ◽  
S. Kagami ◽  
S. Tsutsumi
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Experimental Studies ◽  
Rolling Resistance ◽  
Leading Edge ◽  
Forward Direction ◽  
Contact Pressure Distribution ◽  
Support Ring ◽  
One Dimensional ◽  
Lowered Pressure

Abstract The contact pressure distribution and the rolling resistance of a running radial tire under load are fundamental properties of the tire construction, important to the steering performance of automobiles, as is well known. Many theoretical and experimental studies have been previously published on these tire properties. However, the relationships between tire performances in service and tire structural properties have not been clarified sufficiently due to analytical and experimental difficulties. In this paper, establishing a spring support ring model made of a composite belt ring and a Voigt type viscoelastic spring system of the sidewall and the tread rubber, we analyze the one-dimensional contact pressure distribution of a running tire at speeds of up to 60 km/h. The predicted distribution of the contact pressure under appropriate values of damping coefficients of rubber is shown to be in good agreement with experimental results. It is confirmed by this study that increasing velocity causes the pressure to rise at the leading edge of the contact patch, accompanied by the lowered pressure at the trailing edge, and further a slight movement of the contact area in the forward direction.

A Relativistic Newtonian Mechanics Predicts with Precision the Results of Recent Neutrino-Velocity Experiments

2014 ◽  
Vol 6 (1) ◽  
pp. 1032-1035 ◽  
Author(s):  
Ramzi Suleiman
Keyword(s):  
Null Hypothesis ◽  
Experimental Studies ◽  
Theoretical Models ◽  
Newtonian Mechanics ◽  
Speed Of Light ◽  
Symmetry Principle ◽  
Proposed Model ◽  
Significant Difference ◽  
The One ◽  
Complete Collapse

The research on quasi-luminal neutrinos has sparked several experimental studies for testing the "speed of light limit" hypothesis. Until today, the overall evidence favors the "null" hypothesis, stating that there is no significant difference between the observed velocities of light and neutrinos. Despite numerous theoretical models proposed to explain the neutrinos behavior, no attempt has been undertaken to predict the experimentally produced results. This paper presents a simple novel extension of Newton's mechanics to the domain of relativistic velocities. For a typical neutrino-velocity experiment, the proposed model is utilized to derive a general expression for . Comparison of the model's prediction with results of six neutrino-velocity experiments, conducted by five collaborations, reveals that the model predicts all the reported results with striking accuracy. Because in the proposed model, the direction of the neutrino flight matters, the model's impressive success in accounting for all the tested data, indicates a complete collapse of the Lorentz symmetry principle in situation involving quasi-luminal particles, moving in two opposite directions. This conclusion is support by previous findings, showing that an identical Sagnac effect to the one documented for radial motion, occurs also in linear motion.

Non-stationary process characteristics of the gas outflow into a liquid

2019 ◽  
Vol 14 (2) ◽  
pp. 82-88
Author(s):  
M.V. Alekseev ◽  
I.S. Vozhakov ◽  
S.I. Lezhnin
Keyword(s):  
Numerical Simulation ◽  
Liquid Column ◽  
Gas Content ◽  
Liquid Lead ◽  
Gas Flows ◽  
Asymptotic Model ◽  
Process Characteristics ◽  
Significant Difference ◽  
Order Of Magnitude ◽  
Volume Method

A numerical simulation of the process of the outflow of gas under pressure into a closed container partially filled with liquid was carried out. For comparative theoretical analysis, an asymptotic model was used with assumptions about the adiabaticity of the gas outflow process and the ideality of the liquid during the oscillatory one-dimensional motion of the liquid column. In this case, the motion of the liquid column and the evolution of pressure in the gas are determined by the equation of dynamics and the balance of enthalpy. Numerical simulation was performed in the OpenFOAM package using the fluid volume method (VOF method) and the standard k-e turbulence model. The evolution of the fields of volumetric gas content, velocity, and pressure during the flow of gas from the high-pressure chamber into a closed channel filled with liquid in the presence of a ”gas blanket“ at the upper end of the channel is obtained. It was shown that the dynamics of pulsations in the gas cavity that occurs when the gas flows into the closed region substantially depends on the physical properties of the liquid in the volume, especially the density. Numerical modeling showed that the injection of gas into water occurs in the form of a jet outflow of gas, and for the outflow into liquid lead, a gas slug is formed at the bottom of the channel. Satisfactory agreement was obtained between the numerical calculation and the calculation according to the asymptotic model for pressure pulsations in a gas projectile in liquid lead. For water, the results of calculations using the asymptotic model give a significant difference from the results of numerical calculations. In all cases, the velocity of the medium obtained by numerical simulation and when using the asymptotic model differ by an order of magnitude or more.

scholarly journals Effect of Pressure Distribution on the Energy Dissipation of Lap Joints under Equal Pre-tension Force

Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 320-328
Author(s):  
Delin Sun ◽  
Minggao Zhu
Keyword(s):  
Energy Dissipation ◽  
Pressure Distribution ◽  
Theoretical Basis ◽  
Lap Joints ◽  
Power Exponent ◽  
Lap Joint ◽  
Stick Slip ◽  
Pressure Distributions ◽  
Hysteretic Characteristics ◽  
Effective Use

Abstract In this paper, the energy dissipation in a bolted lap joint is studied using a continuum microslip model. Five contact pressure distributions compliant with the power law are considered, and all of them have equal pretension forces. The effects of different pressure distributions on the interface stick-slip transitions and hysteretic characteristics are presented. The calculation formulation of the energy dissipation is introduced. The energy dissipation results are plotted on linear and log-log coordinates to investigate the effect of the pressure distribution on the energy distribution. It is shown that the energy dissipations of the lap joints are related to the minimum pressure in the overlapped area, the size of the contact area and the value of the power exponent. The work provides a theoretical basis for further effective use of the joint energy dissipation.

Comparative Study for the Assay of Plant Derived Chemicals in Pharmaceutical Formulation Using Methods Dependent on Factorized Spectra

2021 ◽  
Author(s):  
Nesma M Fahmy ◽  
Adel M Michael
Keyword(s):  
Pharmaceutical Formulations ◽  
Pharmaceutical Formulation ◽  
Ternary Mixtures ◽  
Ratio Method ◽  
The Novel ◽  
Naturally Occurring ◽  
Accuracy And Precision ◽  
Validation Parameters ◽  
Significant Difference

Abstract Background Modern built-in spectrophotometer software supporting mathematical processes provided a solution for increasing selectivity for multicomponent mixtures. Objective Simultaneous spectrophotometric determination of the three naturally occurring antioxidants—rutin(RUT), hesperidin(HES), and ascorbic acid(ASC)—in bulk forms and combined pharmaceutical formulation. Method This was achieved by factorized zero order method (FZM), factorized derivative method (FD1M), and factorized derivative ratio method (FDRM), coupled with spectrum subtraction(SS). Results Mathematical filtration techniques allowed each component to be obtained separately in either its zero, first, or derivative ratio form, allowing the resolution of spectra typical to the pure components present in Vitamin C Forte® tablets. The proposed methods were applied over a concentration range of 2–50, 2–30, and 10–100 µg/mL for RUT, HES, and ASC, respectively. Conclusions Recent methods for the analysis of binary mixtures, FZM and FD1M, were successfully applied for the analysis of ternary mixtures and compared to the novel FDRM. All were revealed to be specific and sensitive with successful application on pharmaceutical formulations. Validation parameters were evaluated in accordance with the International Conference on Harmonization guidelines. Statistical results were satisfactory, revealing no significant difference regarding accuracy and precision. Highlights Factorized methods enabled the resolution of spectra identical to those of pure drugs present in mixtures. Overlapped spectra of ternary mixtures could be resolved by spectrum subtraction coupled FDRM (SS-FDRM) or by successive application of FZM and FD1M.

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