scholarly journals Effect of Imperfections Due to Material Heterogeneity on the Offset of Polysilicon MEMS Structures

Sensors ◽  
2019 ◽  
Vol 19 (15) ◽  
pp. 3256 ◽  
Author(s):  
Aldo Ghisi ◽  
Stefano Mariani
Keyword(s):  
Grain Size ◽  
Monte Carlo ◽  
Residual Stresses ◽  
Polycrystalline Material ◽  
Stochastic Approach ◽  
Statistical Distributions ◽  
Lognormal Distributions ◽  
Statistical Fluctuations ◽  
Size And Morphology ◽  
Grain Topology

Monte Carlo analyses on statistical volume elements allow quantifying the effect of polycrystalline morphology, in terms of grain topology and orientation, on the scattering of the elastic properties of polysilicon springs. The results are synthesized through statistical (lognormal) distributions depending on grain size and morphology: such statistical distributions are an accurate and manageable alternative to numerically-burdensome analyses. Together with this quantification of material property uncertainties, the effect of the scattering of the over-etch on the stiffness of the supporting springs can also be accounted for, by subdividing them into domains wherein statistical fluctuations are assumed not to exist. The effectiveness of the proposed stochastic approach is checked with the problem of the quantification of the offset from the designed configuration, due to the residual stresses, for a statically-indeterminate MEMS structure made of heterogeneous (polycrystalline) material.

scholarly journals Polysilicon MEMS Sensors: Sensitivity to Sub-Micron Imperfections

Proceedings ◽  
2018 ◽  
Vol 4 (1) ◽  
pp. 35
Author(s):  
Aldo Ghisi ◽  
Marco Victor Geninazzi ◽  
Stefano Mariani
Keyword(s):  
Grain Size ◽  
Monte Carlo ◽  
Elastic Properties ◽  
Grain Morphology ◽  
Statistical Distributions ◽  
Mems Sensors ◽  
Micro Fabrication ◽  
Mean Values ◽  
Lognormal Distributions ◽  
Size And Morphology

In this work, through Monte Carlo analyses on statistical volume elements, we show the effect of the grain morphology and orientation on the effective elastic properties of polysilicon beams constituting critical MEMS components. The outcomes of the numerical investigation are summarized through statistical (lognormal) distributions for the elastic properties as functions of grain size and morphology, quantifying therefore not only the relevant expected mean values, but also the scattering around them. Such statistical distributions represent a simple, yet rigorous alternative to cumbersome numerical analyses. Their utility is testified through the analysis of a statically indeterminate MEMS structure, quantifying the possible initial offset away from the designed configuration due to the residual stresses arising from the micro-fabrication process.

STOCHASTIC CALCULATION OF LIFETIME PREDICTION FOR COMPONENTS IN METAL STRUCTURES DUE TO THE GROWTH OF MICRODEFECTS

2020 ◽  
Vol 4 (97) ◽  
pp. 69-76
Author(s):  
IGOR N. SILVERSTOV
Keyword(s):  
Fatigue Strength ◽  
Fracture Mechanics ◽  
Stochastic Approach ◽  
Fatigue Curve ◽  
Probability Of Failure ◽  
Lifetime Prediction ◽  
Statistical Distributions ◽  
Metal Structures

A stochastic approach has been developed to evaluate fatigue strength using elements of the fracture mechanics. The article presents a method for determining the initial parameters of statistical distributions. It also considers the method for constructing a fatigue curve for a component of any size and configuration with any given probability of failure.

Simulation of Fabrication for Al2O3 Ceramic Tool Materials

2012 ◽  
Vol 500 ◽  
pp. 537-543 ◽  
Author(s):  
Bin Fang ◽  
Chuan Zhen Huang ◽  
Hong Tao Zhu ◽  
Chong Hai Xu
Keyword(s):  
Grain Size ◽  
Monte Carlo ◽  
Microstructure Evolution ◽  
Potts Model ◽  
Single Phase ◽  
Ceramic Tool ◽  
Tool Materials ◽  
Fabrication Parameters

The new Monte Carlo Potts model that couples with fabrication parameters and considers pores and additives has been developed in order to simulate the fabrication of single-phase ceramics tool materials. The microstructure evolution for single-phase Al2O3 ceramic tool materials is simulated with the different technology parameters. At the same time, the single-phase Al2O3 ceramic tool materials are fabricated with the corresponding technology parameters. The errors of grain size between the simulated and the experimental is 12.1 and18.2%.

scholarly journals Geometry of meandering and braided gravel-bed threads from the Bayanbulak Grassland, Tianshan, P. R. China

2016 ◽  
Vol 4 (1) ◽  
pp. 273-283 ◽  
Author(s):  
François Métivier ◽  
Olivier Devauchelle ◽  
Hugo Chauvet ◽  
Eric Lajeunesse ◽  
Patrick Meunier ◽  
...  
Keyword(s):  
Grain Size ◽  
Scaling Laws ◽  
Sedimentary Basin ◽  
Bedload Transport ◽  
Braided River ◽  
Statistical Distributions ◽  
Meandering Rivers ◽  
Gravel Bed ◽  
Threshold Theory ◽  
Gravel Bed Rivers

Abstract. The Bayanbulak Grassland, Tianshan, P. R. China, is located in an intramontane sedimentary basin where meandering and braided gravel-bed rivers coexist under the same climatic and geological settings. We report and compare measurements of the discharge, width, depth, slope and grain size of individual threads from these braided and meandering rivers. Both types of threads share statistically indistinguishable regime relations. Their depths and slopes compare well with the threshold theory, but they are wider than predicted by this theory. These findings are reminiscent of previous observations from similar gravel-bed rivers. Using the scaling laws of the threshold theory, we detrend our data with respect to discharge to produce a homogeneous statistical ensemble of width, depth and slope measurements. The statistical distributions of these dimensionless quantities are similar for braided and meandering threads. This suggests that a braided river is a collection of intertwined threads, which individually resemble those of meandering rivers. Given the environmental conditions in Bayanbulak, we furthermore hypothesize that bedload transport causes the threads to be wider than predicted by the threshold theory.

Influence of residual stresses and grain size on the spinodal decomposition of metastable Ti1−xAlxN coatings

2012 ◽  
Vol 209 ◽  
pp. 190-196 ◽  
Author(s):  
N. Schalk ◽  
C. Mitterer ◽  
J. Keckes ◽  
M. Penoy ◽  
C. Michotte
Keyword(s):  
Grain Size ◽  
Residual Stresses ◽  
Spinodal Decomposition

scholarly journals Formation of Residual Stresses during Discontinuous Friction Treatment

2021 ◽  
Vol 8 (1) ◽  
pp. C38-C44
Author(s):  
I. Hurey ◽  
V. Gurey ◽  
M. Bartoszuk ◽  
T. Hurey
Keyword(s):  
Grain Size ◽  
Residual Stresses ◽  
Mineral Oil ◽  
Surface Shape ◽  
Technological Medium ◽  
Flat Surfaces ◽  
Compressive Stresses ◽  
Friction Treatment ◽  
Working Surface ◽  
Pass Through

The tool with grooves on its working surface is used to improve the properties of the strengthened layer. This allows us to reduce the structure’s grain size and increase the thickness of the layer and its hardness. Mineral oil and mineral oil with active additives containing polymers are used as a technological medium during friction treatment. It is shown that the technological medium used during the friction treatment affects the nature of the residual stresses’ distribution. Thus, when using mineral oil with active additives containing polymers, residual compressive stresses are more significant in magnitude and depth than when treating mineral oil. The nature of the residual stresses diagram depends on the treated surface’ shape. After friction treatment of cylindrical surfaces, the highest compressive stresses near the treated surface decreases with depth. And after friction treatment of flat surfaces near the treated surface, the compressive stresses are small. They increase with depth, pass through the maximum, and then decrease to the original values. The technological medium used during friction treatment affects residual stresses in the grains and in the crystal lattice.

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