A Method for Generating Desired Contact Pressure Distributions in Experimental Interfacial Studies

1985 ◽  
Vol 107 (3) ◽  
pp. 241-246 ◽  
Author(s):  
M. H. Attia ◽  
L. Kops
Keyword(s):  
Rigid Body ◽  
Contact Pressure ◽  
Flexural Rigidity ◽  
Thermal Contact ◽  
Contact Length ◽  
Wear Testing ◽  
Elastic Response ◽  
Rigid Base ◽  
Two Dimensional ◽  
Pressure Distributions

Computer simulation of the thermal deformation behavior of machine tools requires a priori knowledge of the correlation between the contact pressure distribution and the thermal contact resistance distribution along the structural joint. To establish this correlation experimentally, a method for generating different distributions of contact pressure has been devised in the present work. The method provides also a basic tool toward the satisfaction of the requirements of simulative wear testing. In this paper, the effect of the relative flexural rigidity of two solids in contact on the shape of the distribution of contact pressure is presented as a means for generating desired contact pressure distributions. The theoretical background of the concept is discussed considering two limiting cases: a rigid body on an elastic semi-infinite mass, and an elastic layer on a rigid base. Through a photoelastic analysis, the geometric parameters of contacting bodies, which allow us to generate the desired distributions, have been defined. The results of the analysis were verified by a two-dimensional, plane-stress finite element model. The results indicated that a finite plate, whose dimensions are not less than threefold the contact length can simulate a two-dimensional rigid base or a semi-infinite elastic mass. A change in the height-to-contact length ratio of the contacting beam from 0.5 to 2.5, causes a significant change in its elastic response from a flexural to a rigid body.

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.

The Departure from Equilibrium of Turbulent Boundary Layers

1968 ◽  
Vol 19 (1) ◽  
pp. 1-19 ◽  
Author(s):  
H. McDonald
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Kinetic Energy ◽  
Stress Distribution ◽  
Boundary Layers ◽  
Turbulent Boundary Layers ◽  
Two Dimensional ◽  
Pressure Distributions ◽  
Momentum Integral ◽  
State Examination

SummaryRecently two authors, Nash and Goldberg, have suggested, intuitively, that the rate at which the shear stress distribution in an incompressible, two-dimensional, turbulent boundary layer would return to its equilibrium value is directly proportional to the extent of the departure from the equilibrium state. Examination of the behaviour of the integral properties of the boundary layer supports this hypothesis. In the present paper a relationship similar to the suggestion of Nash and Goldberg is derived from the local balance of the kinetic energy of the turbulence. Coupling this simple derived relationship to the boundary layer momentum and moment-of-momentum integral equations results in quite accurate predictions of the behaviour of non-equilibrium turbulent boundary layers in arbitrary adverse (given) pressure distributions.

Three-dimensional flow in cavities

1963 ◽  
Vol 16 (4) ◽  
pp. 620-632 ◽  
Author(s):  
D. J. Maull ◽  
L. F. East
Keyword(s):  
Static Pressure ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Three Dimensional Flow ◽  
Large Span ◽  
Dimensional Flow ◽  
Pressure Distributions ◽  
Oil Flow ◽  
Two Dimensional Flow

The flow inside rectangular and other cavities in a wall has been investigated at low subsonic velocities using oil flow and surface static-pressure distributions. Evidence has been found of regular three-dimensional flows in cavities with large span-to-chord ratios which would normally be considered to have two-dimensional flow near their centre-lines. The dependence of the steadiness of the flow upon the cavity's span as well as its chord and depth has also been observed.

scholarly journals Test Rig for Applied Experimental Investigations of the Thermal Contact Resistance at the Blade-Rotor-Connection in a Steam Turbine

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
Dennis Toebben ◽  
Xavier E. R. de Graaf ◽  
Piotr Luczynski ◽  
Manfred Wirsum ◽  
Wolfgang F. D. Mohr ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Steam Turbine ◽  
Contact Pressure ◽  
Rotational Speed ◽  
Thermal Contact Resistance ◽  
Thermal Stresses ◽  
Thermal Contact ◽  
Experimental Investigations ◽  
Molybdenum Steel ◽  
Bottle Neck

Recent studies have shown that in a prewarming, respectively, warm-keeping operation of a steam turbine, the blades and vanes transport most of the heat to the thick-walled casing and rotor. Thereby, a thermal bottle-neck arises at the connection between the blade root and the rotor. The thermal contact resistance (TCR) at these interfaces affects the temperature distribution and thus the thermal stresses in the rotor. The present paper introduces an experimental setup, which is designed to quantify the TCR at the blade-rotor-connection of a steam turbine. An uncertainty analysis is presented, which proves that the average measurement uncertainties are less than one percent. The experiments especially focus on the investigation of the contact pressure, which is a function of the rotational speed. Therefore, the results of several steady-state measurements under atmospheric and evacuated atmosphere using a high temperature-resistant chromium-molybdenum steel are presented. For the evaluation of the TCR, a numerical model of the specimen is developed in addition to a simplified 1D approach. The results show a significantly increasing TCR with decreasing contact pressure, respectively, rotational speed.

Flow Fields in a Two-Dimensional Diffuser With Extraction of Fluid on the Diverging Walls

1972 ◽  
Vol 94 (3) ◽  
pp. 226-232
Author(s):  
D. O. Rockwell
Keyword(s):  
Experimental Verification ◽  
Static Pressure ◽  
Flow Fields ◽  
Hydrogen Bubble ◽  
Two Dimensional ◽  
Stagnation Region ◽  
Pressure Distributions

A theory is developed to describe the inviscid core in two-dimensional unstalled diffusers with suction (extraction) on the diverging walls. Experimental wall static pressure distributions and streamline patterns agree well with those predicted theoretically. Under appropriate extraction conditions, a stagnation region is located downstream of the diverging wall extraction station. Experimental verification of the streamline patterns and of the location of this stagnation region was achieved via hydrogen bubble visualization. In addition, the possible stall conditions, which result if improper extraction is employed, are described qualitatively.

scholarly journals Contribution to the Study of Solid-Solid Thermal Contact Resistances--A Comparative Study

2021 ◽  
Vol 45 (4) ◽  
pp. 267-272
Author(s):  
Rahmouna Cheriet ◽  
Bourassia Bensaad ◽  
Fatiha Bouhadjela ◽  
Soufyane Belhenini ◽  
Mohammed Belharizi
Keyword(s):  
Contact Resistance ◽  
Contact Pressure ◽  
Mixed Method ◽  
Thermal Contact Resistance ◽  
Low Cost ◽  
Thermal Contact ◽  
Three Dimensional ◽  
Empirical Models ◽  
Three Dimensional Finite Element ◽  
Semi Empirical

This study presents a mixed numerical / semi-empirical approach that primarily aimed to estimate the thermal contact resistance between two solids. The results obtained by this mixed method were compared and validated by experimental measurements of this resistance. Three semi-empirical models were used, namely the Mikic model, the Yovanovich model and the Antonetti model. The three-dimensional finite element numerical simulation was used to estimate the contact pressure between the two solids. Then this contact pressure obtained numerically was compared to the hardness of the solids in contact. The findings indicated that the numerically obtained contact pressures were close to hardness. Therefore, the hardness, which is usually used as an input variable in semi-empirical models, was replaced by the contact pressure. The thermal contact resistance obtained by this mixed method was then compared with the experimental one. The outcomes obtained from this comparison turned out to be very conclusive and can therefore be used to reinforce our approach which can actually be viewed as a reliable and low-cost method for estimating the thermal contact resistance between solids in contact.

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