Experimental Investigation of the Time Delay Between a Varying Applied Normal Force and the Resulting Friction Force

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Guangxiong Chen ◽  
Xiaolu Cui
Keyword(s):  
Time Delay ◽  
Friction Force ◽  
Normal Force ◽  
Excitation Frequency ◽  
Experimental Tests ◽  
Generation Mechanism ◽  
Test Results ◽  
Test Apparatus ◽  
Force Measurements ◽  
Force Signal

Recently, one of the present authors proposed a new model to explain the generation mechanism of brake squeal based on the time delay between a varying applied normal force and the resulting friction force. The present work conducts a series of experimental tests examining the behavior of this time delay using a special test apparatus. The test apparatus suppresses the effect of interference in the time delay owing to the excitation normal force to the greatest extent possible. Several calibration tests of the test apparatus are conducted to ensure the validity of the normal force and friction force measurements. The varying friction force is extracted from the overall friction force signal without phase distortion using a zero-phase filter. The test results demonstrate a time delay between the varying normal force and the resulting friction force under various testing parameters. The time delay is found to increase with increasing excitation frequency. The generation mechanism of the time delay is also discussed.

Experimental study on the temperature of the contact strip in sliding electric contact

2017 ◽  
Vol 231 (10) ◽  
pp. 1268-1275 ◽  
Author(s):  
GX Chen ◽  
Y Hu ◽  
BJ Dong ◽  
HJ Yang ◽  
GQ Gao ◽  
...  
Keyword(s):  
Electric Current ◽  
Normal Force ◽  
Experimental Tests ◽  
Wear Volume ◽  
Test Results ◽  
Electric Contact ◽  
Sliding Speed ◽  
Factors Affecting ◽  
Contact Wire ◽  
Sliding Electric Contact

Using a ring-on-block tester with AC, the authors accomplished several experimental tests on the temperature of the contact wire and strip in sliding electric contact. In the test, the temperature of the samples, arc voltage, electric current, and wear volume of the strip were collected. Influences of the normal force, sliding speed, and electric current on the temperature of the contact wire and strip were studied. Test results show that the temperature of the carbon strip increases with the increasing of sliding speed and electric current or the decreasing of normal force. The strip wear rate is linearly related with the temperature of the strip. Moreover, the factors affecting the strip temperature were also discussed.

On axial compressive behavior of steel fiber reinforced concrete confined by FRP

2021 ◽  
pp. 136943322098165
Author(s):  
Hossein Saberi ◽  
Farzad Hatami ◽  
Alireza Rahai
Keyword(s):  
Reinforced Concrete ◽  
Experimental Test ◽  
Steel Fiber ◽  
Experimental Tests ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Test Results ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Frp Confinement

In this study, the co-effects of steel fibers and FRP confinement on the concrete behavior under the axial compression load are investigated. Thus, the experimental tests were conducted on 18 steel fiber-reinforced concrete (SFRC) specimens confined by FRP. Moreover, 24 existing experimental test results of FRP-confined specimens tested under axial compression are gathered to compile a reliable database for developing a mathematical model. In the conducted experimental tests, the concrete strength was varied as 26 MPa and 32.5 MPa and the steel fiber content was varied as 0.0%, 1.5%, and 3%. The specimens were confined with one and two layers of glass fiber reinforced polymer (GFRP) sheet. The experimental test results show that simultaneously using the steel fibers and FRP confinement in concrete not only significantly increases the peak strength and ultimate strain of concrete but also solves the issue of sudden failure in the FRP-confined concrete. The simulations confirm that the results of the proposed model are in good agreement with those of experimental tests.

scholarly journals Methodology for Selecting the Operating Conditions of a Vibration Generator Used in the Hot-Dip Galvanizing Process

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2042
Author(s):  
Wojciech Kacalak ◽  
Igor Maciejewski ◽  
Dariusz Lipiński ◽  
Błażej Bałasz
Keyword(s):  
Simulation Model ◽  
Asynchronous Motor ◽  
Experimental Tests ◽  
Suspension System ◽  
Operating Conditions ◽  
Test Results ◽  
Forced Simulation

A simulation model and the results of experimental tests of a vibration generator in applications for the hot-dip galvanizing process are presented. The parameters of the work of the asynchronous motor forcing the system vibrations were determined, as well as the degree of unbalance enabling the vibrations of galvanized elements weighing up to 500 kg to be forced. Simulation and experimental tests of the designed and then constructed vibration generator were carried out at different intensities of the unbalanced rotating mass of the motor. Based on the obtained test results, the generator operating conditions were determined at which the highest values of the amplitude of vibrations transmitted through the suspension system to the galvanized elements were obtained.

Experimental and Theoretical Rotordynamic Characteristics of a Hybrid Journal Bearing

1997 ◽  
Vol 119 (1) ◽  
pp. 132-141 ◽  
Author(s):  
J. T. Sawicki ◽  
R. J. Capaldi ◽  
M. L. Adams
Keyword(s):  
Journal Bearing ◽  
Operating Conditions ◽  
Dynamic Force ◽  
Test Results ◽  
Force Measurements ◽  
Lubrication Equation ◽  
Load Cells ◽  
Theoretical Predictions ◽  
Stiffness And Damping

This paper describes an experimental and theoretical investigation of a four-pocket, oil-fed, orifice-compensated hydrostatic bearing including the hybrid effects of journal rotation. The test apparatus incorporates a double-spool-shaft spindle which permits independent control over the journal spin speed and the frequency of an adjustable-magnitude circular orbit, for both forward and backward whirling. This configuration yields data that enables determination of the full linear anisotropic rotordynamic model. The dynamic force measurements were made simultaneously with two independent systems, one with piezoelectric load cells and the other with strain gage load cells. Theoretical predictions are made for the same configuration and operating conditions as the test matrix using a finite-difference solver of Reynolds lubrication equation. The computational results agree well with test results, theoretical predictions of stiffness and damping coefficients are typically within thirty percent of the experimental results.

Composite Fretting Wear of Aluminum Alloy

2007 ◽  
Vol 353-358 ◽  
pp. 868-873 ◽  
Author(s):  
Min Hao Zhu ◽  
Zhong Rong Zhou
Keyword(s):  
Plastic Deformation ◽  
Aluminum Alloy ◽  
Relative Motion ◽  
Wear Mechanism ◽  
Normal Force ◽  
Fretting Wear ◽  
Test Results ◽  
Contact Configuration ◽  
Inclined Angle ◽  
Flat Contact

A complex relative motion of fretting combined by dual motions of radial and tangential fretting was achieved on a modified fretting tester. The composite fretting motion was induced by the action of an oscillating normal force in a sphere-on-inclined flat contact (52100 steel ball against 2091 aluminum alloy). Two types of inclined angles (45° and 60°) were used in the tests. Variations of veridical force vs displacement have been recorded and analyzed as a function of cycles. Effects of the cyclic normal force and the inclined angle were discussed. The test results showed that wear, cracking and plastic deformation accumulation with a strong dissymmetry in damage morphology was observed. A transformation of fretting mode from composite to radial fretting mode occurred due to a strong modification at local contact configuration. As a conclusion, a physical model for wear mechanism of composite fretting was presented.

Bond of Steel Bars to Masonry Mortar Joints: Test Results and Analytical Modelling

2017 ◽  
Vol 747 ◽  
pp. 319-325 ◽  
Author(s):  
Matteo Maragna ◽  
Cristina Gentilini ◽  
Giovanni Castellazzi ◽  
Christian Carloni
Keyword(s):  
High Strength ◽  
Experimental Tests ◽  
Analytical Investigation ◽  
Masonry Walls ◽  
Test Results ◽  
Bond Slip ◽  
Pull Out ◽  
Steel Bars ◽  
Masonry Mortar

In this paper, the preliminary results of a series of pull-out tests conducted on mortar cylinders with embedded bars are presented. The bars are made of high strength stainless steel and are of helical shape to increase mechanical interlocking with the surrounding mortar. Usually, such bars are employed in situ to realize structural repointing in the case of fair-faced masonry walls. To this aim, they are inserted in the mortar bed joints of masonry for providing tensile strength to the walls and with the function of crack stitching. The aim of the present experimental tests is to determine the bond-slip relationship for bars embedded in masonry. Firstly, pull-out tests are conducted on mortar cylinders considering different embedded lengths of the bars. Further tests are on-going on masonry specimens with bars embedded in the mortar joints. An analytical investigation is also carried out for the interpretation of the pull-out test results.

scholarly journals Investigation of the Performances of a Diesel Engine Operating on Blended and Emulsified Biofuels from Rapeseed Oil

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6661
Author(s):  
Vladimir Anatolyevich Markov ◽  
Bowen Sa ◽  
Sergey Nikolaevich Devyanin ◽  
Anatoly Anatolyevich Zherdev ◽  
Pablo Ramon Vallejo Maldonado ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Rapeseed Oil ◽  
Characteristic Curve ◽  
Motor Fuel ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Test Results ◽  
Cfd Simulations ◽  
Brake Thermal Efficiency ◽  
Flow Simulations

The article discusses the possibility of using blended biofuels from rapeseed oil (RO) as fuel for a diesel engine. RO blended diesel fuel (DF) and emulsified multicomponent biofuels have been investigated. Fuel physicochemical properties have been analyzed. Experimental tests of a diesel engine D-245 in the operating conditions of the external characteristic curve and the 13-mode test cycle have been conducted to investigate the effect of these fuels on engine performances. CFD simulations of the nozzle inner flow were performed for DF and ethanol-emulsified RO. The possibility of a significant improvement in brake thermal efficiency of the engine has been noted. The efficiency of using blended biofuels from RO as a motor fuel for diesel engines has been evaluated based on the experimental test results. It was shown that in comparison with the presence of RO in emulsified multicomponent biofuel, the presence of water has a more significant effect on NOx emission reduction. The content of RO and the content of water in the investigated emulsified fuels have a comparable influence on exhaust smoke reduction. Nozzle inner flow simulations show that the emulsification of RO changes its flow behaviors and cavitation regime.

CAE Correlation of Sealing Pressure of a Press-in-Place Gasket

2021 ◽  
Keyword(s):  
Internal Pressure ◽  
Pressure Distribution ◽  
Load Condition ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Test Results ◽  
Local Pressure ◽  
Cross Sectional ◽  
Pad Test ◽  
Sealing Pressure

The Press-in-Place (PIP) gasket is a static face seal with self-retaining feature, which is used for the mating surfaces of engine components to maintain the reliability of the closed system under various operating conditions. Its design allows it to provide enough contact pressure to seal the internal fluid as well as prevent mechanical failures. Insufficient sealing pressure will lead to fluid leakage, consequently resulting in engine failures. A test fixture was designed to simulate the clamp load and internal pressure condition on a gasket bolted joint. A Sensor pad using TEKSCAN equipment was used to capture the overall and local pressure distribution of the PIP gasket under various engine loading conditions. Then, the Sensor pad test results were compared with simulated CAE results from computer models. Through the comparisons, it is found that the gasket sealing pressure of test data and CAE data show good correlation for bolt load condition 500N when compared to internal pressure side load condition of 0.138 MPa & 0.276 MPa. Moreover, the gasket cross-sectional pressure distribution obtained by experimental tests and CAE models correlated very well with R2 ranging from 90 to 99% for all load cases. Both CAE and Sensor pad test results shows increase in sealing pressure when internal side pressure is applied to the gasket seal.

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