Matching Items (5)

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Development of Tuning Fork-Based Metrology for Study of Casimir Forces Across Nanometric Gaps

Description

This paper discusses the theoretical approximation and attempted measurement of the quantum <br/>force produced by material interactions though the use of a tuning fork-based atomic force microscopy <br/>device. This device

This paper discusses the theoretical approximation and attempted measurement of the quantum <br/>force produced by material interactions though the use of a tuning fork-based atomic force microscopy <br/>device. This device was built and orientated specifically for the measurement of the Casimir force as a <br/>function of separation distance using a piezo actuator for approaching and a micro tuning fork for the <br/>force measurement. This project proceeds with an experimental measurement of the ambient Casmir force <br/>through the use of a tuning fork-based AFM to determine its viability in measuring the magnitude of the <br/>force interaction between an interface material and the tuning fork probe. The ambient measurements <br/>taken during the device’s development displayed results consistent with theoretical approximations, while<br/>demonstrating the capability to perform high-precision force measurements. The experimental results<br/>concluded in a successful development of a device which has the potential to measure forces of <br/>magnitude 10−6 to 10−9 at nanometric gaps. To conclude, a path to material analysis using an approach <br/>stage, alternative methods of testing, and potential future experiments are speculated upon.

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Date Created
  • 2021-05

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Study Thermal Property of Stereolithography 3D Printed Multiwalled Carbon Nanotubes Filled Polymer Nanocomposite

Description

Traditionally, for applications that require heat transfer (e.g. heat exchangers),metals have been the go-to material for manufacturers because of their high thermal as
well as structural properties. However, metals have

Traditionally, for applications that require heat transfer (e.g. heat exchangers),metals have been the go-to material for manufacturers because of their high thermal as
well as structural properties. However, metals have some notable drawbacks. They are
not corrosion-resistant, offer no freedom of design, have a high cost of production, and
sourcing the material itself. Even though polymers on their own don’t show great
prospects in the field of thermal applications, their composites perform better than their
counterparts. Nanofillers, when added to a polymer matrix not only increase their
structural strength but also their thermal performance. This work aims to tackle two of
those problems by using the additive manufacturing method, stereolithography to solve
the problem of design freedom, and the use of polymer nanocomposite material for
corrosion-resistance and increase their overall thermal performance. In this work, three
different concentrations of polymer composite materials were studied: 0.25 wt%, 0.5
wt%, and 1wt% for their thermal conductivity. The samples were prepared by
magnetically stirring them for a period of 10 to 24 hours depending on their
concentrations and then sonicating in an ice bath further for a period of 2 to 3 hours.
These samples were then tested for their thermal conductivities using a Hot Disk TPS
2500S. Scanning Electron Microscope (SEM) to study the dispersion of the nanoparticles
in the matrix. Different theoretical models were studied and used to compare
experimental data to the predicted values of effective thermal conductivity. An increase
of 7.9 % in thermal conductivity of the composite material was recorded for just 1 wt%
addition of multiwalled carbon nanotubes (MWCNTs).

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Created

Date Created
  • 2020

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AFM Bi-material Cantilever Based Near-field Radiation Heat Transfer Measurement

Description

Near-field thermal radiation occurs when the distance between two surfaces at different temperatures is less than the characteristic wavelength of thermal radiation. While theoretical studies predict that the near-field radiative

Near-field thermal radiation occurs when the distance between two surfaces at different temperatures is less than the characteristic wavelength of thermal radiation. While theoretical studies predict that the near-field radiative heat transfer could exceed Planck’s blackbody limit in the far-field by orders of magnitudes depending on the materials and gap distance, experimental measurement of super-Planckian near-field radiative heat flux is extremely challenging in particular at sub-100-nm vacuum gaps and few has been demonstrated. The objective of this thesis is to develop a novel thermal metrology based on AFM bi-material cantilever and experimentally measure near-field thermal radiation.

The experiment setup is completed and validated by measuring the near-field radiative heat transfer between a silica microsphere and a silica substrate and comparing with theoretical calculations. The bi-material AFM cantilever made of SiNi and Au bends with temperature changes, whose deflection is monitored by the position-sensitive diode. After careful calibration, the bi-material cantilever works as a thermal sensor, from which the near-field radiative conductance and tip temperature can be deduced when the silica substrate approaches the silica sphere attached to the cantilever by a piezo stage with a resolution of 1 nm from a few micrometers away till physical contact. The developed novel near-field thermal metrology will be used to measure the near-field radiative heat transfer between the silica microsphere and planar SiC surface as well as nanostructured SiC metasurface. This research aims to enhance the fundamental understandings of radiative heat transfer in the near-field which could lead to advances in microelectronics, optical data storage and thermal systems for energy conversion and thermal management.

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Created

Date Created
  • 2019

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Investigating 3-D Printed Polymer Heat Exchanger

Description

Additive manufacturing, also known as 3-dimensional (3-d) printing, is now a rapidly growing manufacturing technique. Innovative and complex designs in various aspects of engineering have called for more efficient manufacturing

Additive manufacturing, also known as 3-dimensional (3-d) printing, is now a rapidly growing manufacturing technique. Innovative and complex designs in various aspects of engineering have called for more efficient manufacturing techniques and 3-d printing has been a perfect choice in that direction. This research investigates the use of additive manufacturing in fabricating polymer heat exchangers and estimate their effectiveness as a heat transfer device. Fused Deposition Modeling (FDM), Selective Laser Sintering (SLS) and Stereolithography (SLA) are the three 3-d printing techniques that are explored for their feasibility in manufacturing heat exchangers. The research also explores a triply periodic minimal structure–the gyroid, as a heat exchanger design. The performance of the gyroid heat exchanger was studied using experiments. The main parameters considered for the experiments were heat transfer rate, effectiveness and pressure drop. From the results obtained it can be inferred that using polymers in heat exchangers helps reducing corrosion and fouling problems, but it affects the effectiveness of the heat exchangers. For our design, the maximum effectiveness achieved was 0.1. The pressure drop for the heat exchanger was observed to decrease with an increase in flow rate and the maximum pressure drop measured was 0.88 psi for a flow rate of 5 LPM.

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Created

Date Created
  • 2019

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An Investigation into the Stiffness Response of Lattice Shapes under Various Loading Conditions

Description

One of the fundamental aspects of cellular material design is cell shape selection. Of particular interest is how this selection can be made in the context of a realistic three-dimensional

One of the fundamental aspects of cellular material design is cell shape selection. Of particular interest is how this selection can be made in the context of a realistic three-dimensional structure. Towards this goal, this work studied the stiffness response of periodic and stochastic lattice structures for the loading conditions of bending, torsion and tension/compression using commercially available lattice design optimization software. The goal of this computational study was to examine the feasibility of developing a ranking order based on minimum compliance or maximum stiffness for enabling cell selection. A study of stochastic shapes with different seeds was also performed. Experimental compression testing was also performed to validate a sample space of the simulations. The findings of this study suggest that under certain circumstances, stochastic shapes have the potential to generate the highest stiffness-to-weight ratio in the test environments considered.

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Created

Date Created
  • 2019