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Mechanical characterisation of micro-stereolithographic materials
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Xu, Dun (2011) Mechanical characterisation of micro-stereolithographic materials. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b2582299~S1
Abstract
Promising techniques such as micro-stereolithography (MSL) are opening up practical
potential for exploiting new ideas for specialized polymer-based Micro-Electromechanical
systems (MEMS) through small-batch production. As the field matures and
grows, substantial research and commercial development demands better understanding
of mechanical properties of MEMS materials to fully explore the potential of this
technology. Bulk properties derived from conventional testing of large specimens (at 10
mm order) cannot be trusted. However, small-scale specimens (less than 1 mm) introduce
major challenges, such as handling and mounting.
The aim of this study was to contribute towards an improved understanding of the
mechanical properties of the polymers (MSL materials) with a strong emphasis on
developing new metrology. It proposed and described a special form of test-rig and
compatible special MSL specimen design. A uniaxial tensile approach was chosen, partly
because it offered simpler uncertainty models. The prototype used deadweight loading
through a notch flexure, which acted both as a spring in parallel sharing the same
displacement with the specimen and as a linear guideway. The specimen was integrally
fabricated with large clamping regions and support bars released by cutting. Stiffly
constrained mounting and loading surfaces were used to clamp MSL specimens to the
flexure, protecting them against parasitic motions during the test in combination. Strain
was measured through an elongation measurement by high-sensitivity capacitive
micrometry, knowing the specimen dimensions. Verification tests on the clamping
conditions showed no significant evidence of sudden slip or creep.
MSL specimens were fabricated by a projection-based Envisiontec Perfactory system
using a commercial acrylate-based R11 resin. Substantial shrinkage and curl distortion
had been observed, which greatly reduced the fabrication accuracy of the MSL specimens.
Specimens with different UV exposures and different sizes were fabricated and tested for
better understanding of the MSL fabrication process. Typically, Young’s Modulus was a
little smaller than expected and certainly dependent on both size and process parameters
(in the region studied).
Item Type: | Thesis (PhD) | ||||
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Subjects: | T Technology > TK Electrical engineering. Electronics Nuclear engineering | ||||
Library of Congress Subject Headings (LCSH): | Three-dimensional printing, Microelectromechanical systems -- Design and construction | ||||
Official Date: | December 2011 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | School of Engineering | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Chetwynd, D. G. (Derek G.), 1948- | ||||
Extent: | xx, 245 leaves : ill., charts | ||||
Language: | eng |
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