FRICTION PAIR MODELING BY A 2-DOF SYSTEM: NUMERICAL AND EXPERIMENTAL INVESTIGATIONS

2005 ◽  
Vol 15 (06) ◽  
pp. 1931-1944 ◽  
Author(s):  
JAN AWREJCEWICZ ◽  
PAWEŁ OLEJNIK
Keyword(s):  
Numerical Analysis ◽  
Mechanical System ◽  
Degrees Of Freedom ◽  
Normal Force ◽  
Friction Pair ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Object Modeling ◽  
Friction Forces ◽  
Good Agreement

A self-excited friction pair is modeled by a mechanical system of two degrees-of-freedom with a normal force varying during the block displacement. Two different friction coefficients are used, and a normal force pressing the sliding body to a belt depending on an angle bar motion of the analyzed system is applied. In addition, the numerical analysis is supported by the investigation of a real laboratory object modeling the feedback reinforcement of friction forces acting on the block. Both numerical and experimental results are compared showing good agreement.

Numerical and Experimental Investigations of Simple Non-Linear System Modelling a Girling Duo-Servo Brake Mechanism

2003 ◽  
Author(s):  
Jan Awrejcewicz ◽  
Pawel Olejnik
Keyword(s):  
Numerical Analysis ◽  
Linear System ◽  
Coulomb Friction ◽  
Degrees Of Freedom ◽  
Normal Force ◽  
Experimental Investigations ◽  
System Modelling ◽  
Object Modeling ◽  
Friction Forces ◽  
Non Linear System

Our analysis is focused on modeling of friction phenomena exhibited by a brake like duo-servo system. The occurred in girling duo-servo brake an frictional mechanism can be modeled approximately by two degrees-of-freedom mechanical system, where a normal force varies during displacement of a block. The Coulomb friction is used after numerical analysis, and a normal force pressing the sliding body to a belt depending on an angle bar motion of the analyzed system is applied. In addition, the numerical analysis is supported by investigation of the real laboratory object modeling the feedback reinforcement of friction forces acting on the block.

Inducing Frictional Force to Enhance the Transient Response in Beams

2019 ◽  
Vol 22 (2) ◽  
pp. 88-93
Author(s):  
Hamed Khanger Mina ◽  
Waleed K. Al-Ashtrai
Keyword(s):  
Numerical Analysis ◽  
Transient Response ◽  
Frictional Force ◽  
Damping Ratio ◽  
Experimental Results ◽  
Damping Capacity ◽  
Tightening Force ◽  
Contact Areas ◽  
Good Agreement ◽  
Ansys Workbench

This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.

Analysis of Motion of the Impact-Dry-Friction Pair of Bodies and its Application to the Investigation of the Impact Dampers Dynamics

1999 ◽  
Author(s):  
František Peterka
Keyword(s):  
Analytical Solution ◽  
Numerical Simulations ◽  
Mechanical System ◽  
Relative Motion ◽  
Dry Friction ◽  
Friction Pair ◽  
Strong Nonlinearity ◽  
Friction Forces ◽  
The Impact ◽  
Analysis Of Motion

Abstract The motion with impacts and dry friction forces appears in some mechanical systems as mechanisms with clearances, (e.g., in gearings, pins, slots, guides, valve gears etc.), impact dampers, relays, forming and mailing machines, power pics etc. Such mechanisms include one or more pairs of impacting bodies, which introduce the strong nonlinearity into the system motion. The motion of the general pair of bodies with the both-sides impacts and dry friction forces is assumed (Fig.1). It can be the part of a more complex chain of masses in the mechanical system. Dead zones in the relative motion of bodies can be caused by assumed nonlinearities. The mathematical conditions controlling the numerical simulations or analytical solution of the motion are introduced. The application of this method is explained by the study of the influence of dry friction force on amplitude-frequency characteristics of four types of dynamical and impact dampers with optimised parameters.

Flexible chiral metamaterials with dynamically optical activity and high negative refractive index

2015 ◽  
Vol 29 (18) ◽  
pp. 1550087 ◽  
Author(s):  
Furkan Dincer ◽  
Muharrem Karaaslan ◽  
Emin Unal ◽  
Oguzhan Akgol ◽  
Cumali Sabah
Keyword(s):  
Numerical Simulation ◽  
Refractive Index ◽  
Numerical Analysis ◽  
Optical Activity ◽  
Negative Refractive Index ◽  
Experimental Results ◽  
Polarization Converter ◽  
Dynamic Design ◽  
Chiral Metamaterials ◽  
Good Agreement

We demonstrate numerically and experimentally chiral metamaterials (MTMs) based on gammadion-bilayer cross-wires that uniaxially create giant optical activity and tunable circular dichroism as a result of the dynamic design. In addition, the suggested structure gives high negative refractive index due to the large chirality in order to obtain an efficient polarization converter. We also present a numerical analysis in order to show the additional features of the proposed chiral MTM in detail. Therefore, a MTM sensor application of the proposed chiral MTM is introduced and discussed. The presented chiral designs offer a much simpler geometry and more efficient outlines. The experimental results are in a good agreement with the numerical simulation. It can be seen from the results that, the suggested chiral MTM can be used as a polarization converter, sensor, etc. for several frequency regimes.

scholarly journals Assessment of different turbulence models in simulating axisymmetric flow in suddenly expanded nozzles

2018 ◽  
Vol 7 (3.29) ◽  
pp. 243
Author(s):  
Sher Afghan Khan ◽  
Mir Owais Ali ◽  
Miah Mohammed Riyadh ◽  
Zahid Hossen ◽  
Nafis Mahdi Arefin
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Mach Number ◽  
Numerical Simulations ◽  
Axisymmetric Flow ◽  
Turbulence Models ◽  
Experimental Results ◽  
Nozzle Flow ◽  
Axisymmetric Nozzle ◽  
Good Agreement

A numerical simulation was carried out to compare various turbulence models simulating axisymmetric nozzle flow past suddenly expanded ducts. The simulations were done for L/D = 10. The convergent-divergent nozzle has been modeled and simulated using the turbulence models: The Standard k-ε model, The Standard k-ω model and The SST k-ω model. Numerical simulations were done for Mach numbers 1.87, 2.2, and 2.58 and the nozzles were operated for NPRs in the range from 3 to 11. From the numerical analysis it is apparent that for a given Mach number and effect of NPR will result in maximum gain or loss of pressure. Numerical results are in good agreement with the experimental results.  

Experimental Investigations and Modeling of Finishing Force and Torque in Ultrasonic Assisted Magnetic Abrasive Finishing

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Rahul S. Mulik ◽  
Pulak M. Pandey
Keyword(s):  
Mathematical Models ◽  
Normal Force ◽  
Supply Voltage ◽  
Experimental Investigations ◽  
Magnetic Abrasive Finishing ◽  
Factors Affecting ◽  
Finishing Process ◽  
Abrasive Finishing ◽  
Ultrasonic Assisted ◽  
Good Agreement

An ultrasonic assisted magnetic abrasive finishing (UAMAF) process uses an ultrasonic vibrations and magnetic abrasive finishing (MAF) process. In a finishing process there are two types of forces that act during the finishing of the workpiece by UAMAF, namely, normal force and cutting force. The finishing forces have direct influence on the generation of the finished surface and accuracy of the workpiece. Therefore, in the present work, normal force and finishing torque have been measured at various processing conditions during UAMAF. Supply voltage to the electromagnet and finishing gap have been found to be the significant factors affecting the finishing forces and torque. Mathematical models based on process physics have been developed to predict the finishing force and torque. The developed models predict force and torque as a function of supply voltage, machining gap, and workpiece hardness. The developed mathematical models for normal force and finishing torque have been validated and were found to be in good agreement with experimental results.

Experimental Investigation and FE Modelling of Contact Mechanics Phenomenon in Reciprocating Hydraulic U-Seals for Defence Applications

2014 ◽  
Vol 592-594 ◽  
pp. 1950-1954 ◽  
Author(s):  
Shankar Bhaumik ◽  
S.R. Kumar ◽  
Adepu Kumaraswamy
Keyword(s):  
Contact Mechanics ◽  
Contact Pressure ◽  
Experimental Results ◽  
Fe Model ◽  
Friction Measurement ◽  
Fe Modelling ◽  
Friction Forces ◽  
Fluctuating Pressure ◽  
Peak Pressures ◽  
Good Agreement

In this article, an attempt was made to investigate the contact mechanics phenomenon of the reciprocating hydraulic U-seal by measuring friction forces at various pressures and velocities. The inlet fluctuating pressure and the rod speed was simultaneously performed at the peak pressures of 10, 20 and 30MPa and the rod speeds of, 0.12, 0.3 and 0.5 m/s. The distribution of the contact pressure at the seal/rod interface was calculated along the contact surface at pressures of 10, 20 and 30MPa using FE model. Friction measurement of reciprocating seals by experimental results demonstrated that the velocity of the rod and seal pressure influences the seal performance considerably. Furthermore, the numerical analysis undertaken to determine the contact pressure to compute friction force was in good agreement with the experimental results.

Energy Absorption Capability of Composite Hexagonal Array Systems: Numerical Analysis

2018 ◽  
Vol 878 ◽  
pp. 61-69 ◽  
Author(s):  
Farah Alkhatib ◽  
Elsadig Mahdi
Keyword(s):  
Numerical Analysis ◽  
Energy Absorption ◽  
Software Package ◽  
Experimental Results ◽  
Hexagonal Array ◽  
Maximum Value ◽  
Single Column ◽  
Energy Absorbing ◽  
Deformation Modes ◽  
Good Agreement

In this paper, in-plane dynamic crushing test of E-Glass hexagonal array systems has been carried out numerically, using LS-DYNA FE software package. Two array systems of woven E-Glass/epoxy hexagonal were studied; single column array system and multi-column array system. The volume of material used in all models was constant. The significant effects of changing arrays’ sequences and number of E-Glass layers in the hexagonal cells on the energy absorption capability are investigated. To validate the FEM, a single 45º hexagonal was modelled and crushed in X1 direction; the obtained numerical results were compared with the experimental results in terms of energy absorption capability, deformation modes and load-displacement curves, showing good agreement. Results obtained from single column array system showed that 1×4 array exhibited the higher energy absorption capability, whereas in multi-column array system, 4×3 array had the maximum value of energy absorbing compared to the whole studied models in this paper. As a conclusion, the multi-column array system has a higher energy absorption capability compared to the single column array system.

PHOTOINDUCED NONLINEAR OCTUPOLAR POLARIZATION: TRANSIENT AND PERMANENT REGIMES

1996 ◽  
Vol 05 (04) ◽  
pp. 653-670 ◽  
Author(s):  
CÉLINE FIORINI ◽  
JEAN-MICHEL NUNZI ◽  
FABRICE CHARRA ◽  
IFOR D.W. SAMUEL ◽  
JOSEPH ZYSS
Keyword(s):  
Theoretical Analysis ◽  
Second Harmonic ◽  
Experimental Results ◽  
Polar Field ◽  
Rotational Spectrum ◽  
Dual Frequency ◽  
One Dimensional ◽  
Ethyl Violet ◽  
Disperse Red 1 ◽  
Good Agreement

An original poling method using purely optical means and based on a dual-frequency interference process is presented. We show that the coherent superposition of two beams at fundamental and second-harmonic frequencies results in a polar field with an irreducible rotational spectrum containing both a vector and an octupolar component. This enables the method to be applied even to molecules without a permanent dipole such as octupolar molecules. After a theoretical analysis of the process, we describe different experiments aiming at light-induced noncentrosymmetry performed respectively on one-dimensional Disperse Red 1 and octupolar Ethyl Violet molecules. Macroscopic octupolar patterning of the induced order is demonstrated in both transient and permanent regimes. Experimental results show good agreement with theory.

Packing Effect on the Transfer Integrals and Mobility in α,α′-bis(dithieno[3,2-b:2′,3′-d]thiophene) (BDT) and its Heteroatom-Substituted Analogues

2011 ◽  
Vol 64 (12) ◽  
pp. 1587 ◽  
Author(s):  
Ahmad Irfan ◽  
Abdullah G. Al-Sehemi ◽  
Shabbir Muhammad ◽  
Jingping Zhang
Keyword(s):  
Electron Transfer ◽  
Electron Mobility ◽  
Hole Mobility ◽  
Experimental Investigations ◽  
Hole Transfer ◽  
Space Group ◽  
Space Groups ◽  
Transfer Integrals ◽  
Packing Effect ◽  
Good Agreement

Theoretically calculated mobility has revealed that BDT is a hole transfer material, which is in good agreement with experimental investigations. The BDT, NHBDT, and OBDT are predicted to be hole transfer materials in the C2/c space group. Comparatively, hole mobility of BHBDT is 7 times while electron mobility is 20 times higher than the BDT. The packing effect for BDT and designed crystals was investigated by various space groups. Generally, mobility increases in BDT and its analogues by changing the packing from space group C2/c to space groups P1 or . In the designed ambipolar material, BHBDT hole mobility has been predicted 0.774 and 3.460 cm2 Vs–1 in space groups P1 and , which is 10 times and 48 times higher than BDT (0.075 and 0.072 cm2 Vs–1 in space groups P1 and ), respectively. Moreover, the BDT behaves as an electron transfer material by changing the packing from the C2/c space group to P1 and .

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