The Evolution of Geometry for a Wearing Circular Cam: Analytical and Computer Simulation With Comparison to Experiment

Dickrell, Daniel J.; Dooner, David B.; Sawyer, W. Gregory

doi:10.1115/1.1504092

Cited by 32 publications

(17 citation statements)

References 4 publications

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“…These thin films pose two main problems for the design engineer: (1) they wear during operation and thus have finite life, and (2) they are often poor performers in the Earth's environment where they are operated prior to launch and deployment. Bulk polymeric composites containing Polytetrafluoroethylene (PTFE) offer an attractive option to the design engineers because of their predictable operational life [4,5], ability to operate from cryogenic temperature (4 K) to 500 K, and their relative insensitivity to oxygen and humidity [3].…”

Section: Introductionmentioning

confidence: 99%

Cryogenic Friction Behavior of PTFE based Solid Lubricant Composites

et al. 2005

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Solid lubricants used in aerospace applications must provide low friction and a predictable operation life over an extreme range of temperatures, environments and contact conditions. PTFE and PTFE composites have shown favorable tribological performance as solid lubricants. This study evaluates the effect of temperature on the friction coefficient of neat PTFE, a PTFE/ PEEK composite and an expanded PTFE (ePTFE)/epoxy coating. These experiments evaluate friction coefficient over a temperature span which, to the investigators' knowledge, has not been previously examined. Results show a monotonic increase in friction coefficient as sample surface temperature was decreased from 317 to 173 K for all three samples. The frictional performance of these and other published solid lubricant polymers was modeled using an adjusted Arrhenius equation, which correlates the coefficient of friction of the polymer materials to their viscoelastic behavior. A model fit of all the polymer data from 173 to 450 K gives an activation energy of 3.7 kJ/mol. This value suggests that breaking of van der Waals bonds is the likely mechanism responsible for the frictional behavior over this temperature range.

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Section: Introductionmentioning

confidence: 99%

Cryogenic Friction Behavior of PTFE based Solid Lubricant Composites

et al. 2005

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“…In this work, we will show experiments related to an eccentric circular cam, which are often used to produce motion in pumps or to operate steam engine valves [35]. Other examples of various applications based on the eccentric circular cam can be found in [10,14,20,22,50]. The use of circular cams in the automotive field is instead reported in [13,44].…”

Section: Descriptionmentioning

confidence: 97%

“…Namely, from Fig. 10, it follows that := (x, y): y = tan(θ f )x − d cos(θ f ) (20) and then, since we can define ∇ = [− sin(θ f ) cos(θ f )], we obtain…”

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confidence: 99%

Experimental and numerical verification of bifurcations and chaos in cam-follower impacting systems

et al. 2007

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In this paper we present the design, modelling and experimental validation of a novel experimental cam-follower rig for the analysis of bifurcations and chaos in piecewise-smooth dynamical systems with impacts. Experimental results are presented for a cam-follower system characterized by a radial cam and a flat-faced follower. Under variation of the cam rotational speed, the follower is observed to detach from the cam and then show the emergence of periodic impacting behaviour characterized by many impacts and chattering. Further variations of the cam speed cause the sudden transition to seemingly aperiodic behaviour. These results are compared with the numerical simulation of a mathematical model of the system which shows the same qualitative behaviour. Excellent quantitative agreement is found between the numerical and experimental results

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“…To date, many techniques have been proposed to simulate wear that range from molecular dynamics to simple analytical models (Blanchet (1997), Sawyer (2001), Dickrell and Sawyer (2004), Telliskivi (2004), Põdra and Andersson (1999b), Mukras et al (2009), Johansson (1994, Dickrell et al (2003), Kim et al (2005), Rowe et al (2014), Sawyer (2004), Sawyer et al (2014), Jang et al (2007)). Most often the approach consists in simulating the wear evolution of a surface with iterative schemes by assuming a relation between material removal rates and local contact pressures.…”

Section: Introductionmentioning

confidence: 99%

“…Formally optimizing wear performance is the focus of this article. In particular, sliding abrasive wear will be considered because simplified mechanical models have already been developed and experimentally validated for this kind of wear (Põdra and Andersson (1999b), Fregly et al (2005), Kim et al (2005), Blanchet (1997), Dickrell et al (2003), Sawyer (2004), Rowe et al (2014)). Predicting wear performance remains an open domain, rich with challenges for industries aiming to design systems with improved or target wear characteristics (Tankala and Kapoor (2001), Barron (1982), Prasad (2000)).…”

Section: Introductionmentioning

confidence: 99%

Introducing a level-set based shape and topology optimization method for the wear of composite materials with geometric constraints

Feppon

Michailidis

Sidebottom

et al. 2016

Struct Multidisc Optim

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The wear of materials continues to be a limiting factor in the lifetime and performance of mechanical systems with sliding surfaces. As the demand for low wear materials grows so does the need for models and methods to systematically optimize tribological systems. Elastic foundation models offer a simplified framework to study the wear of multimaterial composites subject to abrasive sliding. Previously, the evolving wear profile has been shown to converge to a steady-state that is characterized by a time-independent elliptic equation. In this article, the steady-state formulation is generalized and integrated with shape optimization to improve the wear performance of bi-material composites. Both macroscopic structures and periodic material microstructures are considered. Several common tribological objectives for systems undergoing wear are identified and mathematically formalized with shape derivatives. These include (i) achieving a planar wear surface from multimaterial composites and (ii) minimizing the run-in volume of material lost before steady-state F. Feppon wear is achieved. A level-set based topology optimization algorithm that incorporates a novel constraint on the levelset function is presented. In particular, a new scheme is developed to update material interfaces; the scheme (i) conveniently enforces volume constraints at each iteration, (ii) controls the complexity of design features using perimeter penalization, and (iii) nucleates holes or inclusions with the topological gradient. The broad applicability of the proposed formulation for problems beyond wear is discussed, especially for problems where convenient control of the complexity of geometric features is desired.

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The Evolution of Geometry for a Wearing Circular Cam: Analytical and Computer Simulation With Comparison to Experiment

Cited by 32 publications

References 4 publications

Cryogenic Friction Behavior of PTFE based Solid Lubricant Composites

Cryogenic Friction Behavior of PTFE based Solid Lubricant Composites

Experimental and numerical verification of bifurcations and chaos in cam-follower impacting systems

Introducing a level-set based shape and topology optimization method for the wear of composite materials with geometric constraints

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