Improvement of the flexural strength of a product by computer-aided analysis, CAA techniques

Pao Yue-kong Library Electronic Theses Database

Improvement of the flexural strength of a product by computer-aided analysis, CAA techniques


Author: Yuen, Chi-cheong
Title: Improvement of the flexural strength of a product by computer-aided analysis, CAA techniques
Degree: M.Sc.
Year: 1997
Subject: Design, Industrial -- Data processing
Finite element method
Hong Kong Polytechnic University -- Dissertations
Department: Multi-disciplinary Studies
Pages: ix, 111 p. : ill. (some col.) ; 31 cm
Language: English
InnoPac Record:
Abstract: Current computer aided design tools in Hong Kong are seldom integrated with computer aided analysis and non-destructive testing techniques. The design optimization is usually achieved, based on experimental results obtained from prototype testing. This form of product design approach is much more time consuming and expensive compared to the procedures used by manufacturers in competing countries, such as Japan. Since 70% of the production cost of a product is expended during the initial design concept formulation stage, cost reduction measures are thus most effectively factored in this phase. Thus, shape optimization of the product can be performed by integrating computer aided design and computer aided analysis, with the improved design verified experimentally. By integrating the three components, the number of design iterations can be substantially reduced, saving both time and effort during the design concept formulation stage. This thesis describes the investigation of the improvement of flexural strength of the casing of an electronic product by integrating numerical analysis and experimental evaluation techniques. The casing is made of Acrylonitrile Butadiene Styrene (ABS), which is a thermoplastic resin. The performance of the original design is evaluated by a non-destructive experimental technique: holographic interferometry. The flexural strength of the design is then improved using a computer based numerical analysis technique: finite element method. The performance of the improved design is again evaluated experimentally using holographic interferometry to correlate with the results from finite element method. Double exposure technique for holographic interferometry is used to evaluate the performance of the original and improved design. This method is used to determine the out-of-plane displacement of the design. The optical scene scattered from the object can be recorded and reconstructed in the hologram as a three dimensional image. The laser beam used in our holographic interferometry system is He-Ne gas laser with wavelength of 633nm. The flexural strength of the casing has been evaluated, improved, and verified by finite element analysis and holographic interferometry. The battery compartment has been improved so that no leakage and gap is found. The speaker grills have been redesigned so that the centrally applied external loading on the speaker grills is shared among the grills. The frames of the improved casing are subjected to a more uniform displacement distribution on both sides of the casing, together with a smaller maximum principal stress.

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