Describing function of two masses with backlash

Duarte, Fernando B.; Machado, J. A. Tenreiro

doi:10.1007/s11071-008-9410-y

Cited by 33 publications

(28 citation statements)

References 10 publications

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“…The motivation for this research work comes from current interest in developing mathematical and computational tools for the dynamics of multibody systems in which the effects of clearance, surface compliance, friction and lubrication in real joints are taken into account [1][2][3][4][5][6]. These phenomena can be included in a multibody system with a spherical joint, and in many applications the function of the mechanical systems strongly depends on them.…”

Section: Introductionmentioning

confidence: 99%

Spatial rigid-multibody systems with lubricated spherical clearance joints: modeling and simulation

2009

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The dynamic modeling and simulation of spatial rigid-multi-body systems with lubricated spherical joints is the main purpose of the present work. This issue is of paramount importance in the analysis and design of realistic multibody mechanical systems undergoing spatial motion.When the spherical clearance joint is modeled as dry contact; i.e., when there is no lubricant between the mechanical elements which constitute the joint, a body-to-body (typically metal-tometal) contact takes place. The joint reaction forces in this case are evaluated through a Hertzian-based contact law. A hysteretic damping factor is included in the dry contact force model to account for the energy dissipation during the contact process. The presence of a fluid lubricant avoids the direct metal-to-metal contact. In this situation, the squeeze film action, due to the relative approaching motion between the mechanical joint elements, is considered utilizing the lubrication theory associated with the spherical bearings. In both cases, the intrajoint reaction forces are evaluated as functions of the geometrical, kinematical and physical characteristics of the spherical joint. These forces are then incorporated into a standard formulation of the system's governing equations of motion as generalized external forces. A spatial four bar mechanism that includes a spherical clearance joint is considered here as example. The computational simulations are carried out with and without the fluid lubricant, and the results are compared with those obtained when the system is modeled with perfect joints only. From the general results it is observed that the system's performance with lubricant effect presents fewer peaks in the kinematic and dynamic outputs, when compared with those from the dry contact joint model.

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Section: Introductionmentioning

confidence: 99%

Spatial rigid-multibody systems with lubricated spherical clearance joints: modeling and simulation

2009

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“…This approach gives the net change in velocity of each body and the energy exchange during collisions [43][44][45][46][47]. Let us consider the impact of two bodies along surfaces that are normal to the line connecting their centres of mass.…”

Section: Dynamic Backlashmentioning

confidence: 99%

Dynamics of a backlash chain

Machado¹

2013

Open Physics

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“…-S , a second order system G (s) 1 followed by a static backlash [47,48] s (s+1) with width t>, = 1, and -S , a second order system with delay G (s) 1 e −s .…”

Section: Application In Control Systemsmentioning

confidence: 99%

Optimal Controllers with Complex Order Derivatives

Machado

2012

J Optim Theory Appl

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This paper studies the optimization of complex-order algorithms for the discrete-time control of linear and nonlinear systems. The fundamentals of fractional systems and genetic algorithms are introduced. Based on these concepts, complexorder control schemes and their implementation are evaluated in the perspective of evolutionary optimization. The results demonstrate not only that complex-order derivatives constitute a valuable alternative for deriving control algorithms, but also the feasibility of the adopted optimization strategy.

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Describing function of two masses with backlash

Cited by 33 publications

References 10 publications

Spatial rigid-multibody systems with lubricated spherical clearance joints: modeling and simulation

Spatial rigid-multibody systems with lubricated spherical clearance joints: modeling and simulation

Dynamics of a backlash chain

Optimal Controllers with Complex Order Derivatives

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