Modeling of a Rolling Flexible Spherical Shell

2016 ◽  
Vol 83 (9) ◽  
Author(s):  
François Robert Hogan ◽  
James Richard Forbes
Keyword(s):  
Spherical Shell ◽  
Numerical Simulations ◽  
Dynamic Model ◽  
Nonholonomic Constraint ◽  
Flat Surface ◽  
Lagrangian Approach ◽  
Martian Surface ◽  
Motion Equations ◽  
Thin Walls

The purpose of this paper is to develop the motion equations of a flexible spherical shell rolling without slip on a flat surface. The motivation for this paper stems from tumbleweed rovers, which are envisioned to roll, deform, and bounce on the Martian surface due to the flexible nature of their thin walls. The motion equations are derived using a constrained Lagrangian approach and capture the rolling without slip nonholonomic constraint. Numerical simulations are performed to validate the dynamic model developed and to investigate the effect of the flexibility of the spherical shell on its trajectory.

Dynamic Modeling of a Rolling Flexible Sphere

2015 ◽  
Author(s):  
François Robert Hogan ◽  
James Richard Forbes ◽  
Alex Walsh
Keyword(s):  
Spherical Shell ◽  
Numerical Simulations ◽  
Dynamic Model ◽  
Dynamic Modeling ◽  
Flat Surface ◽  
Free Vibrations ◽  
Lagrangian Formulation ◽  
Discretization Method ◽  
Motion Equations

The motion equations of a rolling flexible spherical shell are derived using a Lagrangian formulation. The motion equations developed capture the nonholonomic nature of the flexible sphere rolling without slip on a flat surface. The free vibrations of the spherical shell are modeled using the Rayleigh-Ritz discretization method. Numerical simulations are performed to validate the dynamic model developed and to investigate the effect of the flexibility of the spherical shell on its trajectory.

Modeling of a Rolling Flexible Circular Ring

2015 ◽  
Vol 82 (11) ◽  
Author(s):  
François Robert Hogan ◽  
James Richard Forbes
Keyword(s):  
Numerical Simulations ◽  
Dynamic Model ◽  
Lagrange Multipliers ◽  
Flat Surface ◽  
Ritz Method ◽  
Free Vibrations ◽  
Circular Ring ◽  
Ring Rolling ◽  
Motion Equations ◽  
Out Of Plane

The motion equations of a rolling flexible circular ring are derived using a Lagrangian formulation. The in-plane flexural and out-of-plane twist-bending free vibrations are modeled using the Rayleigh–Ritz method. The motion equations of a flexible circular ring translating and rotating in space are first developed and then constrained to roll on a flat surface by introducing Lagrange multipliers. The motion equations developed capture the nonholonomic nature of the circular ring rolling without slip on a flat surface. Numerical simulations are performed to validate the dynamic model developed and to investigate the effect of the flexibility of the circular ring on its trajectory. The vibrations of the circular ring are observed to impact the ring's motion.

Modeling and validation of crankshaft speed fluctuations of a single-cylinder four-stroke diesel engine

2021 ◽  
pp. 095440702110262
Author(s):  
Mustafa Babagiray ◽  
Hamit Solmaz ◽  
Duygu İpci ◽  
Fatih Aksoy
Keyword(s):  
Diesel Engine ◽  
Dynamic Model ◽  
Moment Of Inertia ◽  
Mass Motion ◽  
Cylinder Pressure ◽  
Motion Equations ◽  
Single Cylinder ◽  
Mass Moment ◽  
Mass Moment Of Inertia ◽  
Speed Fluctuations

In this study, a dynamic model of a single-cylinder four-stroke diesel engine has been created, and the crankshaft speed fluctuations have been simulated and validated. The dynamic model of the engine consists of the motion equations of the piston, conrod, and crankshaft. Conrod motion was modeled by two translational and one angular motion equations, by considering the kinetic energy resulted from the mass moment of inertia and conrod mass. Motion equations involve in-cylinder gas pressure forces, hydrodynamic and dry friction, mass inertia moments of moving parts, starter moment, and external load moment. The In-cylinder pressure profile used in the model was obtained experimentally to increase the accuracy of the model. Pressure profiles were expressed mathematically using the Fourier series. The motion equations were solved by using the Taylor series method. The solution of the mathematical model was performed by coding in the MATLAB interface. Cyclic speed fluctuations obtained from the model were compared with experimental results and found compitable. A validated model was used to analyze the effects of in-cylinder pressure, mass moment of inertia of crankshaft and connecting rod, friction, and piston mass. In experiments for 1500, 1800, 2400, and 2700 rpm engine speeds, crankshaft speed fluctuations were observed as 12.84%, 8.04%, 5.02%, and 4.44%, respectively. In simulations performed for the same speeds, crankshaft speed fluctuations were calculated as 10.45%, 7.56%, 4.49%, and 3.65%. Besides, it was observed that the speed fluctuations decreased as the average crankshaft speed value increased. In the simulation for 157.07, 188.49, 219.91, 251.32, and 282.74 rad/s crankshaft speeds, crankshaft speed fluctuations occurred at rates of 10.45%, 7.56%, 5.84%, 4.49%, and 3.65%, respectively. The effective engine power was achieved as 5.25 kW at an average crankshaft angular speed of 219.91 rad/s. The power of friction loss in the engine was determined as 0.68 kW.

Experimental Model Validation for a Flexible Robot With a Prismatic Joint

1990 ◽  
Vol 112 (3) ◽  
pp. 315-323 ◽  
Author(s):  
Ye-Chen Pan ◽  
A. Galip Ulsoy ◽  
R. A. Scott
Keyword(s):  
Rigid Body ◽  
Numerical Simulations ◽  
Dynamic Model ◽  
Experimental Model ◽  
Model Validation ◽  
Solution Method ◽  
Flexible Robot ◽  
Spherical Coordinate ◽  
Prismatic Joints ◽  
Rigid Body Motions

In [1] a dynamic model for flexible manipulators with prismatic joints and the solution method were presented. In this paper experiments on a spherical coordinate robot are performed to further validate the proposed dynamic model. Using the validated model, numerical simulations are performed to illustrate the coupling effects between the rigid body motions and the flexible motions, the effects of the flexible motion on a rigid body controller, and the effects of axial shortening.

Numerical simulations of self-propelled jumping upon drop coalescence on non-wetting surfaces

2014 ◽  
Vol 752 ◽  
pp. 39-65 ◽  
Author(s):  
Fangjie Liu ◽  
Giovanni Ghigliotti ◽  
James J. Feng ◽  
Chuan-Hua Chen
Keyword(s):  
Numerical Simulations ◽  
Liquid Bridge ◽  
Flat Surface ◽  
Three Dimensional ◽  
Superhydrophobic Surfaces ◽  
Ohnesorge Number ◽  
Drop Coalescence ◽  
Out Of Plane ◽  
Potential Applications ◽  
Cutoff Radius

AbstractCoalescing drops spontaneously jump out of plane on a variety of biological and synthetic superhydrophobic surfaces, with potential applications ranging from self-cleaning materials to self-sustained condensers. To investigate the mechanism of self-propelled jumping, we report three-dimensional phase-field simulations of two identical spherical drops coalescing on a flat surface with a contact angle of 180°. The numerical simulations capture the spontaneous jumping process, which follows the capillary–inertial scaling. The out-of-plane directionality is shown to result from the counter-action of the substrate to the impingement of the liquid bridge between the coalescing drops. A viscous cutoff to the capillary–inertial velocity scaling is identified when the Ohnesorge number of the initial drops is around 0.1, but the corresponding viscous cutoff radius is too small to be tested experimentally. Compared to experiments on both superhydrophobic and Leidenfrost surfaces, our simulations accurately predict the nearly constant jumping velocity of around 0.2 when scaled by the capillary–inertial velocity. By comparing the simulated drop coalescence processes with and without the substrate, we attribute this low non-dimensional velocity to the substrate intercepting only a small fraction of the expanding liquid bridge.

Avoiding Instability on the Milling of Parts with Thin Features

2006 ◽  
Vol 526 ◽  
pp. 37-42 ◽  
Author(s):  
Francisco Javier Campa ◽  
Luis Norberto López de Lacalle ◽  
S. Herranz ◽  
Aitzol Lamikiz ◽  
A. Rivero
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Spindle Speed ◽  
Depth Of Cut ◽  
Test Device ◽  
High Speed Milling ◽  
Thin Walls ◽  
Chatter Vibrations ◽  
The Stability ◽  
Selection Of

In this paper, a 3D dynamic model for the prediction of the stability lobes of high speed milling is presented, considering the combined flexibility of both tool and workpiece. The main aim is to avoid chatter vibrations on the finish milling of aeronautical parts, which include thin walls and thin floors. In this way the use of complex fixtures is eliminated. Hence, an accurate selection of both axial depth of cut and spindle speed can be accomplished. The model has been validated by means of a test device that simulates the behaviour of a thin floor.

scholarly journals Study on Dynamic Response of Straddle-Type Monorail Vehicle with Single-Axle Bogie Under Curve Condition

Mechanika ◽  
2021 ◽  
Vol 27 (2) ◽  
pp. 122-129
Author(s):  
Liang XIN ◽  
Zixue DU ◽  
Junchao ZHOU ◽  
Zhen YANG ◽  
Zhouzhou XU
Keyword(s):  
Dynamic Response ◽  
Dynamic Model ◽  
Degrees Of Freedom ◽  
Contact Model ◽  
Beam Model ◽  
Test Results ◽  
Motion Equations ◽  
Lagrange’S Equation ◽  
Curve Radius ◽  
Track Beam

This paper is concerned with the dynamic response of straddle-monorail with single-axle bogie under curve condition. A 15 degrees-of-freedom(DOF) dynamic model is established for straddle-type monorail vehicle with single-axle bogie, which consists driving wheels, steering wheels and stabilizing wheels. The motion equations of the straddle-type monorail vehicle are derived using the Lagrange's equation, and the wheel-rail contact model and the curving track beam model are created. Compared with the test results, the accuracy of the method is verified. Finally, the influence of curve radius, curve superelevation rate, number of passengers and stiffness of driving wheels on dynamic response is discussed.

Dynamical Analysis of the 2-Dimensional Tentacle Robot

2010 ◽  
Vol 166-167 ◽  
pp. 209-214 ◽  
Author(s):  
Mihaela Florescu ◽  
Anca Petrisor ◽  
Daniela Coman
Keyword(s):  
Numerical Simulations ◽  
Dynamic Model ◽  
Special Class ◽  
Dynamical Analysis ◽  
Arm Motion

The paper deals with a special class of robots, namely the hyper-redundant arm with continuum elements. First, the dynamic model of the tentacle arm during the motion toward the imposed position is analyzed. The dynamic model of the tentacle arm with continuum elements in conjunction with the electro-rheological fluid is discussed. Also, numerical simulations of the arm motion to the imposed target are presented.

scholarly journals Fast numerical simulations of 2D turbulence using a dynamic model for subfilter motions

2004 ◽  
Vol 196 (1) ◽  
pp. 184-207 ◽  
Author(s):  
J.-P. Laval ◽  
B. Dubrulle ◽  
S.V. Nazarenko
Keyword(s):  
Numerical Simulations ◽  
Dynamic Model ◽  
2D Turbulence
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