Experimental and Numerical Studies on Thermally-Induced Slip Ratcheting on a Slope

Mild temperature fluctuation of a material sitting on a slope may only cause a small slip, but a large number of the repeated temperature changes can amplify the magnitude of the overall slip and eventually bring an issue of structural instability. The slip accumulation starts from the minor magnitude and reaches the extensive level called “slip ratcheting”. Experimental evidence for such thermally-induced slip ratcheting is first provided in this work. It is implemented with an acryl sheet placed on an inclined wood with a mild angle; it is found that the temperature fluctuation of the acryl sheet causes the sheet to slide down gradually without any additional loading. The numerical model is then attempted to emulate the major findings of the experiments. From the simulation work, the location of a neutral point is found when the acryl plate is heated, and another neutral point is observed when cooled down. The shift of the neutral point appears to be a major reason for the unrecovered slip after a temperature increase and decrease cycle. Finally, a parametric study using the numerical model is carried out to examine which parameters play a major role in the development of residual slips.

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Heat Transfer and Thermal Stress Analysis of an Optoelectronic Package

Journal of Electronic Packaging ◽

10.1115/1.2905404 ◽

1991 ◽

Vol 113 (3) ◽

pp. 258-262 ◽

Cited By ~ 2

Author(s):

J. G. Stack ◽

M. S. Acarlar

Keyword(s):

Heat Transfer ◽

Thermal Management ◽

Power Dissipation ◽

Point Of View ◽

Optical Data ◽

Data Link ◽

Element Analysis ◽

Thermally Induced ◽

Temperature Changes ◽

Induced Stresses

The reliability and life of an Optical Data Link transmitter are inversely related to the temperature of the LED. It is therefore critical to have efficient packaging from the point of view of thermal management. For the ODL® 200H devices, it is also necessary to ensure that all package seals remain hermetic throughout the stringent military temperature range requirements of −65 to +150°C. For these devices, finite element analysis was used to study both the thermal paths due to LED power dissipation and the thermally induced stresses in the hermetic joints due to ambient temperature changes

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Pyrolysis in Porous Media: Numerical model and parametric study.

18th AIAA/3AF International Space Planes and Hypersonic Systems and Technologies Conference ◽

10.2514/6.2012-5876 ◽

2012 ◽

Cited By ~ 1

Author(s):

L. Romagnosi ◽

N. Gascoin ◽

E. El-Tabach ◽

C. Strozzi ◽

I. Fedioun ◽

...

Keyword(s):

Porous Media ◽

Numerical Model ◽

Parametric Study

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The Research of Energy Conversion and Heat Transfer in the Ceramic Foams of Solar Energy Converter

Volume 4: Energy Systems Analysis, Thermodynamics and Sustainability; Combustion Science and Engineering; Nanoengineering for Energy, Parts A and B ◽

10.1115/imece2011-63013 ◽

2011 ◽

Author(s):

Yangbo Deng ◽

Fengmin Su ◽

Chunji Yan

Keyword(s):

Heat Transfer ◽

Numerical Model ◽

Solar Radiation ◽

Solar Energy ◽

Numerical Models ◽

Air Flow ◽

Energy Converter ◽

Ceramic Foams ◽

Numerical Studies ◽

Flow Through

The solar energy converter in Concentrated Solar Power (CSP) system, applies the solid frame structure of the ceramic foams to receive the concentrated solar radiation, convert it into thermal energy, and heat the air flow through the ceramic foams by convection heat transfer. In this paper, first, the pressure drops in the studied ceramic foams were measured under all kinds of flow condition. Based on the experimental results, an empirical numerical model was built for the air flow through ceramic foams. Second, a 3-D numerical model was built, for the receiving and conversion of the solar energy in the ceramic foams of the solar energy converter. Third, applying two aforementioned numerical models, the numerical studies of the thermal performance were carried out, for the solar energy converter filled with the ceramic foams, and results show that the structure parameters of the ceramic foams, the effective reflective area and the solar radiation intensity of the solar concentrator, have direct impacts on the absorptivity and conversion efficiency of the solar energy in the solar energy converter. And the results of the numerical studies are found to be in reasonable agreement with the experimental measurements. This paper will provide a reference for the design and manufacture of the solar energy converter with the ceramic foams.

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RANS MODELLING OF CROSS-SHORE SEDIMENT TRANSPORT AND MORPHODYNAMICS IN THE SWASH-ZONE

Coastal Engineering Proceedings ◽

10.9753/icce.v36v.sediment.14 ◽

2020 ◽

pp. 14

Author(s):

Joost Kranenborg ◽

Geert Campmans ◽

Niels Jacobsen ◽

Jebbe van der Werf ◽

Robert McCall ◽

...

Keyword(s):

Sediment Transport ◽

Numerical Model ◽

Navier Stokes ◽

Swash Zone ◽

Rans Equations ◽

Model Based ◽

Numerical Studies ◽

Reynolds Averaged Navier Stokes ◽

Averaged Models

Most numerical studies of sediment transport in the swash zone use depth-averaged models. However, such models still have difficulty predicting transport rates and morphodynamics. Depth-resolving models could give detailed insight in swash processes but have mostly been limited to hydrodynamic predictions. We present a depth-resolving numerical model, based on the Reynolds Averaged Navier-Stokes (RANS) equations, capable of modelling sediment transport and morphodynamics in the swash zone.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/PB8Vs0LJq88

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Transport Mechanisms in Electrokinetic Nanoscale Channels

Fluids Engineering ◽

10.1115/imece2004-61356 ◽

2004 ◽

Cited By ~ 3

Author(s):

Sumita Pennathur ◽

Juan G. Santiago

Keyword(s):

Field Theory ◽

Parametric Study ◽

Nanometer Scale ◽

Transport Mechanisms ◽

Electrokinetic Transport ◽

Zeta Potentials ◽

Numerical Studies ◽

Debye Layer ◽

Model Predictions ◽

Shape And Size

We investigate electrokinetic transport in nanometer-scale fluidic channels. Our study includes numerical studies of nanofluidic transport of both charged and uncharged analytes in conditions of finite Debye layer thickness and high zeta potentials. The models are based on continuum mass transport and field theory. We also perform an experimental parametric study using etched nanoscale channels. Experimental results agree with model predictions and show that bulk electrokinetic transport in nanoscale channels depends strongly on the shape and size of the EDL and on the effects of transverse electrophoretic migration.

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Acute clouding of hydrophilic acrylic copolymer intraocular lenses:four cases report

10.21203/rs.2.333/v1 ◽

2019 ◽

Author(s):

Xiaochen Wang ◽

Yusen Huang ◽

Xiaoming Wu

Keyword(s):

Temperature Fluctuation ◽

The Other ◽

Intraocular Lenses ◽

Transient Temperature ◽

Acrylic Copolymer ◽

Case Presentation ◽

Temperature Changes ◽

Acrylic Copolymers ◽

Handling Methods ◽

Phacoemulsification Cataract Surgery

Abstract Background: Intraoperative acrylic intraocular lenses (IOLs) transient clouding of several kinds of hydrophilic IOLs have been reported due to temperature changes. However, we ignored the particularity of its material and the handling methods. Case presentation: We present four cases of acute clouding of hydrophilic acrylic intraocular lenses (IOLs). Four patients underwent phacoemulsification cataract surgery with implantation of L-312, 809M, and 839M IOLs, respectively. The IOLs became opaque in varying degrees during surgery. Lens replacement was performed immediately in one case, while the cloudy IOLs were remained in the other three cases. Postoperatively, all IOLs recovered transparency. Conclusions：Temperature fluctuation was the cause of the acute opacification of these IOLs made of hydrophilic acrylic copolymers, which reminds us of attaching importance to the temperature of IOL storage and delivery in winter months. Keywords: Opacification, transient, temperature, material, cataract.

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Characterization of Thermally Induced Stress in IC Packages Using PiFETs Over a Temperature Range of −180°C to 80°C

International Symposium on Microelectronics ◽

10.4071/isom-wa46 ◽

2014 ◽

Vol 2014 (1) ◽

pp. 000500-000504 ◽

Cited By ~ 2

Author(s):

Francy J. Akkara ◽

Uday S. Goteti ◽

Richard C. Jaeger ◽

Michael C. Hamilton ◽

Michael J. Palmer ◽

...

Keyword(s):

Shear Stress ◽

Stress Component ◽

Shear Stress Component ◽

Thermally Induced ◽

Temperature Changes ◽

Temperature Range ◽

Induced Stress ◽

Highly Sensitive ◽

Stress Components

In certain applications, IC packages may be exposed to extreme temperatures and knowledge of thermally induced stress aids the prediction of performance degradation or failure of the IC. In the devices that are used in extreme conditions, the stress is caused mainly by the mismatch in expansion of various materials triggered by the different coefficients of thermal expansion. This work performed in this study is conducted using NMOS current mirror circuits that are cycled through a wide temperature range of −180°C to 80°C. These circuits are highly sensitive to stress and provide well-localized measurements of shear stress. The sensors are fabricated in such a way that the effects of certain stress components are isolated. These sensors are also temperature compensated so that only the effect of mechanical stress components is observed and changes in device performance due to temperature changes are minimal. Current readings obtained from the sensors are used to extract the shear stress component. Finite element simulations, using expected materials performance parameter information were also performed for similar packages and these results are compared to the measured results.

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Application of Smoothed Particle Hydrodynamics to Structural Cable Analysis

Applied Sciences ◽

10.3390/app10248983 ◽

2020 ◽

Vol 10 (24) ◽

pp. 8983

Author(s):

A. Ersin Dinçer ◽

Abdullah Demir

Keyword(s):

Numerical Model ◽

Smoothed Particle Hydrodynamics ◽

Solid Mechanics ◽

Numerical Studies ◽

Mesh Free ◽

Longitudinal Stiffness ◽

Damping Parameter ◽

Particle Hydrodynamics ◽

Deformable Bodies ◽

Smoothed Particle

In this study, a numerical model is proposed for the analysis of a simply supported structural cable. Smoothed particle hydrodynamics (SPH)—a mesh-free, Lagrangian method with advantages for analysis of highly deformable bodies—is utilized to model a cable. In the proposed numerical model, it is assumed that a cable has only longitudinal stiffness in tension. Accordingly, SPH equations derived for solid mechanics are adapted for a structural cable, for the first time. Besides, a proper damping parameter is introduced to capture the behavior of the cable more realistically. In order to validate the proposed numerical model, different experimental and numerical studies available in the literature are used. In addition, novel experiments are carried out. In the experiments, different harmonic motions are applied to a uniformly loaded cable. Results show that the SPH method is an appropriate method to simulate the structural cable.

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