Friction measurement and correction method in quasi-static tests of columns under combined axial and cyclic lateral loading

2019 ◽  
Vol 22 (12) ◽  
pp. 2672-2686
Author(s):  
Zeyuan Wang ◽  
Peng Feng ◽  
Shi Cheng ◽  
Tao Yu
Keyword(s):  
Friction Force ◽  
Force Measurement ◽  
Reaction Force ◽  
Lateral Force ◽  
Correction Method ◽  
Friction Measurement ◽  
Measurement Device ◽  
Friction Forces ◽  
Static Tests ◽  
Lateral Friction

In quasi-static tests of large-scale structural columns and/or columns under large axial loads, the lateral friction force between the column and the loading system can become a significant problem: they may cause considerable deviation between the measured lateral force and the actual reaction force of the column, especially under large axial compression load. Many researchers have come up with different methods to reduce or eliminate the influence of such friction force. In this article, previous treatments on the lateral friction force in quasi-static tests are first discussed. A shear force measurement device, for accurate measurement of the friction force, is then presented and calibrated. Based on the friction forces measured by the device in real tests, a simple model is proposed to predict the lateral friction force in quasi-static tests. Using the model, the measured lateral force in such tests can be corrected to obtain the actual reaction force of the column when a friction measurement device is absent. The proposed model and the correction method are then validated using results from several previous tests.

Effects of Particle Concentration in CMP

2001 ◽  
Vol 671 ◽  
Author(s):  
Wonseop Choi ◽  
Seung-Mahn Lee ◽  
Rajiv K. Singh
Keyword(s):  
Friction Force ◽  
Contact Area ◽  
Particle Concentration ◽  
Surface Coverage ◽  
Force Measurement ◽  
Solid Loading ◽  
Friction Forces ◽  
Lateral Friction

ABSTRACTThis paper reports on characterization of the surface coverage of particles by in-situ lateral friction force measurement during chemical mechanical polishing. The lateral friction force apparatus was made to operate close to real CMP conditions. For these experiments a sapphire wafer of constant surface roughness was used. For both 2psi and 4psi down force we observed increase in lateral friction forces with increasing solid loading. The lateral friction forces have been found to be significantly dependent on the contact area at the wafer-pad-slurry interface, thus showing that in-situ dynamic friction force changes in the surface coverage of particles. From these results, we conclude that the enhancement of frictional force is due to increased contact area at the wafer-pad-slurry interfaces. The lateral friction force measurement can provide an understanding of wafer-pad-slurry interactions.

Stiffness and Friction Force Measurements on a Freight Car Truck from Quasi-Static Tests

1984 ◽  
Vol 106 (1) ◽  
pp. 16-20 ◽  
Author(s):  
G. Kachadourian ◽  
C. L. Orth ◽  
D. W. Inskeep
Keyword(s):  
Friction Force ◽  
The Body ◽  
Load Application ◽  
Force Measurements ◽  
Friction Forces ◽  
Static Tests ◽  
Bearing Contact ◽  
Freight Car ◽  
Force Data ◽  
Fixed Section

A conventional three-piece truck with load sensitive friction snubbing was tested as a complete assembly with its wheels resting on a fixed section of rail and with loads applied through a fixture that duplicated the body bolster at the truck bolster interface. The purpose of the testing was to determine the stiffness and friction forces of the truck under vertical, lateral, and roll moment loading conditions. Loads were varied to cover a range of car gross weight conditions. The test was quasi-static in that load application was varied at sinusoidal rates of 0.1 or 0.2 Hertz to minimize errors in spring rate measurement caused by friction snubber forces. The desired stiffness and friction force data were obtained in terms of system rather than component properties and are consequently more directly usable in mathematical models. The roll test data were particularly useful because separate spring rates were obtained for the different conditions of center plate seated, center plate rocking, and side bearing contact. Because of the sinusoidal method of load application, it was possible to obtain system spring rates with the friction snubbers static and sliding.

scholarly journals The Split Friction Model - Introducing Mixed Lubrication to Curling

2021 ◽  
Author(s):  
Martin Ziegler
Keyword(s):  
Friction Force ◽  
Normal Force ◽  
Lateral Force ◽  
Friction Model ◽  
Mixed Lubrication ◽  
Stribeck Curve ◽  
Static Case ◽  
Friction Forces ◽  
Gyroscopic Precession ◽  
Centripetal Forces

Abstract In general, the curling stone is subject to mixed lubrication, resulting in the characteristic Stribeck -curve. As velocity increases, the friction force falls quadratically just to rise linearly yet almost flat after the minimum. In the case of a rotating curling stone this results in a torque. Due to isotropy , the lateral force arises as a delta of asymmetric friction forces opposite to the centripetal forces. \par This in turn allows a split friction model that splits up the quadratic curve into two rather constant values for the friction force on the advancing and the retreating side below a critical velocity difference of these sides: the flee force on the advancing side must not exceed the normal force of the retreating side. Only then a curl can happen. This explains why a stone curls towards the end of the throw. \par Following basic static considerations, the stone may theoretically rest on up to three points during a throw. Each single static case is investigated. These results are discussed with additional heuristic calculations that involve Scratch-Theory. Lastly, the influence of gyroscopic precession yields a graph that reflects established experimental observations: A desired flat curve within deviations ranging from 0.80 to 1.02 meter for up to 20 rotations just to rise linearly up to 2 meters for 80 rotations.

Development of a Knee-gap Force Measurement Device to Evaluate Quantitative Lower Limb Muscular Strength of the Elderly

2010 ◽  
Vol 130 (2) ◽  
pp. 267-274 ◽  
Author(s):  
Kazuhiko Yamashita ◽  
Kazuya Imaizumi ◽  
Yumi Iwakami ◽  
Mitsuru Sato ◽  
Sawako Nakajima ◽  
...  
Keyword(s):  
Lower Limb ◽  
Muscular Strength ◽  
Force Measurement ◽  
The Elderly ◽  
Measurement Device

scholarly journals Influence of Nanoscale Textured Surfaces and Subsurface Defects on Friction Behaviors by Molecular Dynamics Simulation

Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1617 ◽  
Author(s):  
Ruiting Tong ◽  
Zefen Quan ◽  
Yangdong Zhao ◽  
Bin Han ◽  
Geng Liu
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Friction Force ◽  
Copper Substrate ◽  
Dynamics Simulation ◽  
Textured Surfaces ◽  
Friction Forces ◽  
Subsurface Structures ◽  
Texture Orientation ◽  
Subsurface Defects

In nanomaterials, the surface or the subsurface structures influence the friction behaviors greatly. In this work, nanoscale friction behaviors between a rigid cylinder tip and a single crystal copper substrate are studied by molecular dynamics simulation. Nanoscale textured surfaces are modeled on the surface of the substrate to represent the surface structures, and the spacings between textures are seen as defects on the surface. Nano-defects are prepared at the subsurface of the substrate. The effects of depth, orientation, width and shape of textured surfaces on the average friction forces are investigated, and the influence of subsurface defects in the substrate is also studied. Compared with the smooth surface, textured surfaces can improve friction behaviors effectively. The textured surfaces with a greater depth or smaller width lead to lower friction forces. The surface with 45° texture orientation produces the lowest average friction force among all the orientations. The influence of the shape is slight, and the v-shape shows a lower average friction force. Besides, the subsurface defects in the substrate make the sliding process unstable and the influence of subsurface defects on friction forces is sensitive to their positions.

scholarly journals Shearing force measurement device with a built-in integrated micro displacement sensor

2015 ◽  
Vol 221 ◽  
pp. 1-8 ◽  
Author(s):  
Takuma Iwasaki ◽  
Toshihiro Takeshita ◽  
Yuji Arinaga ◽  
Koji Uemura ◽  
Hideyuki Ando ◽  
...  
Keyword(s):  
Force Measurement ◽  
Displacement Sensor ◽  
Shearing Force ◽  
Measurement Device

Numerical and Experimental Study of Turbulent Flows Around Clark Y-14 Aerofoil

2015 ◽  
Author(s):  
Kshitij Vadake ◽  
Jie Cui
Keyword(s):  
Fluid Dynamics ◽  
Wind Tunnel ◽  
Real World ◽  
Force Measurement ◽  
Test Model ◽  
Wind Tunnel Testing ◽  
Cfd Simulations ◽  
Measurement Device ◽  
Tunnel Testing

Experimental Fluid Dynamics (EFD) and Computational Fluid Dynamics (CFD) have been instrumental in Fluid Mechanics to help solve scientific and engineering problems. This research attempts to use both techniques to perform a parametric study of turbulence flow around airfoil ClarkY-14 at various velocity and angle of attack (AoA). Clark Y-14 airfoil was designed in the 1920’s. It demonstrated good overall performance at low and moderate Reynolds numbers. With the progress in the aviation field, its performance was sub-optimal for newer aircraft designs. However, with the advent of RC airplanes and model aircrafts, there is a renewed interest in this airfoil. Various research projects have been conducted using this airfoil, but there hasn’t been a combined EFD and CFD study of the performance characteristics of the airfoil itself, which still finds real world applications today. One important aspect of this research included the investigation of the effects of a Force Measurement Device/Sensor, which is typically used in scaled/full-size wind tunnels to mount the test model as well as measure the forces/moments acting on it during the testing. The presence of such a device could affect the quality of the data obtained from the wind tunnel testing when compared to a real world application scenario where the aforementioned device may not be present. To the best of the author’s knowledge, no detailed study has been published on the effects of such devices. In this study, the results with and without the measuring device were generated by using CFD simulations. The results were then compared to see to what extent the inclusion of these devices will affect the results. The methodology used for this research was experimental as well as computational. In the present research, a commercially available CFD software STAR-CCM+ was employed to simulate the flows around airfoil Clark Y-14. The experimental data was obtained from wind tunnel tests using AEROLAB Educational Wind Tunnel (EWT) and compared with the simulation data from the CFD. The two data sets were in good agreement. Both experimental and simulation results were used to understand the effects of the measurement device/sensor used in the scaled wind tunnel on the lift and drag coefficients of the airfoil. Two separate CFD simulation setups were designed to model the presence and absence of the measurement device/sensor. These setups replicated the wind tunnel setup. The airfoil was tested and simulated at different speeds as well as different AoA. The comparative study gave a useful insight on the accuracy of the CFD simulations in relation to the actual testing. The analysis of results concluded that the force measurement device/sensor had insignificant effects on the accuracy and quality of data collected through wind tunnel testing.

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