scholarly journals An Experimental Study on Effect of Boundary Condition on Particle Damage in Shear Zone of Crushed Sand

2019 ◽  
Vol 124 (9) ◽  
pp. 9546-9561 ◽  
Author(s):  
Nasrin Vafaei ◽  
Kazem Fakharian ◽  
Abouzar Sadrekarimi
Keyword(s):  
Boundary Condition ◽  
Experimental Study ◽  
Shear Zone ◽  
Particle Damage

Experimental study of boundary condition effects on spontaneous imbibition in tight sandstones

Fuel ◽  
2019 ◽  
Vol 235 ◽  
pp. 374-383 ◽  
Author(s):  
Chaohui Lyu ◽  
Zhengfu Ning ◽  
Mingqiang Chen ◽  
Qing Wang
Keyword(s):  
Boundary Condition ◽  
Experimental Study ◽  
Spontaneous Imbibition

Theoretical and Experimental Study on Large Amplitude Vibrations of Clamped Viscoelastic Plates

2016 ◽  
Author(s):  
Prabakaran Balasubramanian ◽  
Giovanni Ferrari ◽  
Zenon J. Guzman N. del Prado ◽  
Marco Amabili
Keyword(s):  
Boundary Condition ◽  
Experimental Study ◽  
Frequency Response ◽  
Large Amplitude ◽  
Continuation Method ◽  
Mode Shapes ◽  
Harmonic Load ◽  
Response Curves ◽  
Voigt Model ◽  
Large Amplitude Vibrations

In this paper, the large amplitude vibrations of clamped-clamped thin viscoelastic rectangular plates due to a concentrated transversal harmonic load are investigated both theoretically and experimentally. Clamped boundary condition on all edges and von Kármán nonlinear strain-displacement relationships are considered while rotary inertia, geometric imperfections, and shear deformation are neglected. In the theoretical study, the viscoelastic behaviour of the material is modelled using the Kelvin-Voigt model. In-plane loads applied during the assembly of the plate are taken into account and clamped boundary conditions are modelled using artificial rotational springs. The nonlinear ordinary differential equations for the considered Kelvin-Voigt model are obtained using the generalized energy approach. These equations contain quadratic and cubic nonlinear viscoelasticity terms in addition to quadratic and cubic stiffness terms. Non-dimensionalization of variables is carried out and each second order equation is converted into two first order equations. The resulting system of equations is solved using AUTO (software based on the arclength continuation method that allows bifurcation analysis), to get the frequency-response curves at various force levels. Moreover numerical time integration of equations was also performed using the fourth-order Runge-Kutta method to understand the time response of the structure. In the experimental study, two rubber plates with different material and thicknesses were considered; a silicone plate with 0.0015 m thickness and a neoprene plate with 0.003 m thickness. The plates were fixed on a heavy rectangular metal frame thereby ensuring the clamped boundary condition on all edges. Linear experimental modal analysis was carried out as a first step to estimate the mode shapes and natural frequencies. In the second step, the nonlinear vibration response of the plate around its first resonance was measured at various harmonic force levels. At each force level, the amplitude of the harmonic excitation was kept constant by LMS Data Acquisition System and Test.Lab Stepped Sine software module while slowly varying the frequency of excitation to get the frequency-response curves. Laser Doppler Vibrometry was used to measure the response from the plate as it eliminates the possible mass loading effect introduced by any contact type sensors. A maximum amplitude of more than three times the thickness of the plate was achieved. The nonlinear response curves showed a typical hardening type nonlinearity along with sudden jumps as expected for plates. Experimental frequency-response curves were compared with theoretical results and a good agreement was found. The influence of nonlinear viscoelastic damping terms was clearly noticed on the response curves of the plate. The retardation time, measured in seconds decreases with increasing excitation force and larger amplitude vibrations.

Modeling and Experimental Study of the Impact on Free Abrasive Machining (FAM) due to Vibration of a Thin Wire Subject to an Oscillating Boundary Condition

2019 ◽  
Author(s):  
Liming Li ◽  
Imin Kao
Keyword(s):  
Boundary Condition ◽  
Experimental Study ◽  
Moving Boundary ◽  
Damping Factor ◽  
Periodic Excitation ◽  
Abrasive Machining ◽  
Vibrating Wire ◽  
Oscillating Boundary ◽  
The Impact ◽  
Free Abrasive

Abstract This paper investigates the impact on free abrasive machining (FAM) process using a vibrating wire with an oscillating boundary condition. The experimental results show that the vibration of wire in slurry with abrasive grits can result in material removal due to FAM on brittle material. We present a theoretical model of a wire moving axially at a constant speed, subject to an oscillating boundary condition with damping, and derive an analytical solution of the partial differential equation of motion. Based on the modeling and analysis, the frequency of vibration of wire corresponds to the frequency at the oscillating boundary at steady state. The damping factor suppresses the lateral movement of wire from the fixed boundary to moving boundary when it is increased. The change of axial wire speed or the oscillating frequency at boundary can counteract the suppression on the vibration response induced by increased damping factor. This study also presents an experimental study using an experimental setup of a slurry-fed wire with a periodic excitation to study the FAM process on silicon. The results of experiments show that vibration of wire can impart the silicon carbide abrasive grits in slurry to generate observable grooves and fractures on the surface of silicon in just a few minutes. The grooves and fractures are generated by the indentation of abrasive grits via loading and unloading on the silicon surface. When the vibrating wire is only fed with water without abrasives or under a dry condition, compressive deformation with shallow grooves on silicon is observed; however, the surface is found to be free of surface features of indentation and scratching. Furthermore, evidence of both wire compression and abrasive machining is more pronounced at the edges of silicon specimen, especially at the edge close to the periodic excitation, which is consistent to our modeling.

Experimental Study of Automotive Aerodynamics in Headlamp Effect

2011 ◽  
Vol 279 ◽  
pp. 339-344
Author(s):  
Lan Fang Jiang ◽  
Hong Liu ◽  
Ai Qi Li
Keyword(s):  
Numerical Simulation ◽  
Boundary Condition ◽  
Experimental Study ◽  
Reynolds Number ◽  
Wind Tunnel ◽  
Drag Coefficient ◽  
Surface Pressure ◽  
Symmetry Plane ◽  
Automotive Aerodynamics ◽  
Inlet Boundary Condition

The effect of headlamp modeling on automotive aerodynamics was studied by wind tunnel tests. Firstly, the effect of Reynolds number on drag coefficient of automotive scaled down models was studied under different velocity of flow to verify the rationality of selecting scale for scaled down model and setting inlet boundary condition. Secondly, drag coefficient of automotive scaled down models with different headlamp modeling design were measured. Thirdly, the distribution of surface pressure on central symmetry plane and headlamp was measured and analyzed. It also validated the validity of preceding numerical simulation. It is of importance to guide the headlamp modeling design and automotive modeling design.

scholarly journals Performance Enhancement of R.C. Beams with Large Web Openings by Using Reactive Powder Composite: An Experimental Study

2018 ◽  
Vol 21 (3) ◽  
pp. 405-416
Author(s):  
Nidaa Qassim Jassim ◽  
Husain Khalaf Jarallah
Keyword(s):  
Experimental Study ◽  
Shear Zone ◽  
Performance Enhancement ◽  
Powder Composite ◽  
Tension Zone ◽  
Compression Zone ◽  
Normal Strength Concrete ◽  
Strength Concrete ◽  
Normal Strength ◽  
Reactive Powder

In this paper an experimental works conducted to study the behavior of R.C. beam with large web opening at different locations and fortified with reactive powder composite (RPC) at the extreme tension zone (bottom edge of opening) and/or extreme compression zone (Top edge of opening). The experimental study is investigate the  behavior of twelve beams and study the ability of using normal strength concrete together with RPC in the same section to exploit the advantages of these two materials in optimal way. The main variables are RPC layers locations in tension zone and/or in compression zone and the locations of openings. The ultimate loads, load mid-span deflection behavior and strain for steel and concrete were discussed. The experimental results showed that the ultimate strength was decreased with increasing number of opening about 4% for beams with two openings located in shear zone and 21% for beams with three openings, thus indicating that the stiffness decreases accordingly. The using RPC layers effectively enhanced performance of hybrid beams when compared with using the normal strength concrete layers only. The using RPC layers in compression and tension zones increased the ultimate load about 47 % for beams with two opening located in shear zone, when using RPC in the tension zone and normal strength concrete in the compression zone the ultimate flexural load and ultimate deflection increase little compared with normal concrete.

Sign in / Sign up

Export Citation Format

Share Document