Rapid manufacturing of non-assembly complex micro-devices by microstereolithography

Yang, Hongyi; Ratchev, Svetan; Turitto, Michele; Segal, Joel

doi:10.1016/s1007-0214(09)70086-0

Cited by 28 publications

(13 citation statements)

References 2 publications

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“…[4], both for journal and thrust bearings. In bearing applications, major performance indices are the load carrying capacity and the friction coefficient.…”

Section: Introductionmentioning

confidence: 99%

Geometry Optimization of Textured Three-Dimensional Micro- Thrust Bearings

Papadopoulos

Efstathiou

Nikolakopoulos

et al. 2011

Journal of Tribology

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This paper presents an optimization study of the geometry of three-dimensional microthrust bearings in a wide range of convergence ratios. The optimization goal is the maximization of the bearing load carrying capacity. The bearings are modeled as microchannels, consisting of a smooth moving wall (rotor), and a stationary wall (stator) with partial periodic rectangular texturing. The flow field is calculated from the numerical solution of the Navier-Stokes equations for incompressible isothermal flow; processing of the results yields the bearing load capacity and friction coefficient. The geometry of the textured channel is defined parametrically for several width-to-length ratios. Optimal texturing geometries are obtained by utilizing an optimization tool based on genetic algorithms, which is coupled to the CFD code. Here, the design variables define the bearing geometry and convergence ratio. To minimize the computational cost, a multi-objective approach is proposed, consisting in the simultaneous maximization of the load carrying capacity and minimization of the bearing convergence ratio. The optimal solutions, identified based on the concept of Pareto dominance, are equivalent to those of singleobjective optimization problems for different convergence ratio values. The present results demonstrate that the characteristics of the optimal texturing patterns depend strongly on both the convergence ratio and the width-to-length ratio. Further, the optimal load carrying capacity increases at increasing convergence ratio, up to an optimal value, identified by the optimization procedure. Finally, proper surface texturing provides substantial load carrying capacity even for parallel or slightly diverging bearings. Based on the present results, we propose simple formulas for the design of textured micro-thrust bearings.

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“…[4], both for journal and thrust bearings. In bearing applications, major performance indices are the load carrying capacity and the friction coefficient.…”

Section: Introductionmentioning

confidence: 99%

Geometry Optimization of Textured Three-Dimensional Micro- Thrust Bearings

Papadopoulos

Efstathiou

Nikolakopoulos

et al. 2011

Journal of Tribology

View full text Add to dashboard Cite

show abstract

“…In the last two decades, a substantially number of numerical and experimental studies has been reported, analyzing the usefulness of surface texturing [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] in fluid film bearings. It is widely accepted that the use of textured surface can be helpful in the design of high load sustaining fluid film bearings.…”

Section: Introductionmentioning

confidence: 99%

“…This made the bearing system to work in hybrid mode. Recent advances in manufacturing techniques 10,11,[13][14][15] such as abrasive jet machining, micro-machining, chemical etching, novel dressing, vibro-mechanical machining, microstereolithography, laser surface texturing (LST), etc. have the capability to produce micro-features over the bearing surface with good dimensional control and repeatability.…”

Section: Introductionmentioning

confidence: 99%

Performance analysis of rough surface hybrid thrust bearing with elliptical dimples

Kumar

Sharma

2020

Proceedings of the Institution of Mechanical Engineers, Part J:

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Surface roughness is inherent to all machining processes. Therefore, even a high precision machining process renders micro-roughness to some extent on the surface of conventional materials. The asperities height of many rough engineering surfaces follows Gaussian distribution. The surface roughness on the bearing surface may significantly affect the bearing performance. Surface texturing is emerging as a new technique to improve the tribological behavior of the mating surfaces. Usually dimensions/height of micro-roughness is of order of the depth of surface textures in fluid film bearings. Neglecting micro-roughness while numerically simulating a textured surface bearing may generate inaccurate bearing performance data. In presented work, finite element simulation of textured surface hybrid thrust bearings has been performed. Surface texture is provided over thrust pad in the form of regular arrays of elliptical dimples. A parametric optimization is carried out to determine optimum attributes of elliptical dimple (axis, depth, texture length and orientation) so that the load-carrying capacity and fluid film stiffness should be maximized and film frictional power losses should be minimized. Use of textured surface (with optimum elliptical dimple attributes) results into a significant enhancement in load-carrying capacity (91.3%), film stiffness coefficient (+98.8%) and reduction in frictional power losses (−48.3%). It is also observed that elliptical dimple and micro-roughness (transverse orientation) generate synergistic effects in further enhancing the load-carrying capacity (+101.4%) and film stiffness coefficient (+112%) of the bearing.

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“…In recent years, textured bearing surface has emerged as a new technology for improving the external load bearing capacity and limiting the dependence of flat land thrust bearings on external supply pumps to support heavy loads. Technological advancement in manufacturing process such as laser surface texturing [6], micro-stereolithography [7] and micromachining facilitates the development of textured bearing surfaces with high degree of accuracy at micron level. Micro-textures over the bearing surfaces act as micro-bearings, which will help in generating additional load-carrying capacity.…”

Section: Introductionmentioning

confidence: 99%

Effect of geometric shape of micro-grooves on the performance of textured hybrid thrust pad bearing

Kumar

Sharma

2019

J Braz. Soc. Mech. Sci. Eng.

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A numerical simulation is performed to investigate the synergizing influence of surface texture (micro-grooves) and electrically conducting lubricant on static and dynamic performance of hybrid thrust pad bearings operating under transverse magnetic field. Linear momentum and mass conservation equation are solved simultaneously to derive modified Reynolds equation for magnetohydrodynamic lubrication. Finite element approach has been used to obtain couple solution of modified Reynolds equation and restrictor (orifice) flow equation. A mass conserving algorithm (Jakobsson-Floberg-Olsson boundary condition) has been implemented to simulate cavitation phenomenon within micro-grooves. A parametric investigation (based on load-carrying capacity/fluid film pressure) is carried out to obtain optimum attributes for various micro-grooves shapes. Providing micro-groove on bearings surfaces results in a significant increase in load-carrying capacity, stiffness coefficient and reduction in frictional power loss of the bearing. Employing of electrically conducting lubricant is seen to be enhancing the load-carrying capacity and damping characteristics of the bearing.

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Rapid manufacturing of non-assembly complex micro-devices by microstereolithography

Cited by 28 publications

References 2 publications

Geometry Optimization of Textured Three-Dimensional Micro- Thrust Bearings

Geometry Optimization of Textured Three-Dimensional Micro- Thrust Bearings

Performance analysis of rough surface hybrid thrust bearing with elliptical dimples

Effect of geometric shape of micro-grooves on the performance of textured hybrid thrust pad bearing

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