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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Optimization of the package of air purifiers

Yang, Yi January 2015 (has links)
This article presents the development of an optimization of the package for a certain air purifier. The new design was more environmentally friendly, cheaper to produce, saves storage space and simplifies the repacking processes. The concept was generated in the concept generation phase, and selected among other concepts with the help of Pugh Matrix. After an iterative development process of cushioning design, drop simulation and drop tests, the proposed concept was verified by drop simulations in ANSYS, drop tests following the ISTA 3A standard, and a brief Life Cycle Assessment. Future work was also proposed based on the findings in the project. The theoretical background of the design, the various methods which were used in the development process and the development process itself were presented and discussed in this article. A method of rapid cushioning development was also concluded. The method was suitable for developing a cushioning system made of pre-compressed corrugated paper board based on an existing cushioning system. The method was designed to achieve a rapid iterative development for a new cushioning design with pre-compressed corrugated paper board based on an existing cushioning design.
2

Effective vibro-acoustical modelling of rubber isolators

Coja, Michael January 2005 (has links)
This thesis, gathering four papers, concerns the enhancement in understanding and modelling of the audible dynamic stiffness of vibration rubber isolators including experimental measurements. Paper A studies the performances of three different types of vibration isolator using an indirect measurement technique to estimate the blocked dynamic transfer stiffness of each specimen. The measurements are performed over a wide audible frequency range of 200 to 1000 Hz in a specially designed test rig enabling the investigation of arbitrary preload influences. Paper B addresses the modelling of the audible-frequency stiffness of the rubber conical mount experimentally appraised in Paper A accounting for preload effects. The model is based on a simpliflied waveguide approach approximating the nonlinearities attributed to the predeformations by adopting shape factor considerations. The carbon black filled rubber is assumed incompressible, displaying a viscoelastic behavior based on a fractional derivative Kelvin-Voigt model efficiently reducing the number of required material parameters. In Paper C the focus is on the axial dynamic stiffness modelling of an arbitrary long rubber bushing within the audible frequency range. The problems of simultaneously satisfying the locally non-mixed boundary conditions at the radial and end surfaces are solved by adopting a waveguide approach, using the dispersion relation for axially symmetric waves in thick-walled infinite plates, while fulfilling the radial boundary conditions by mode-matching. The results obtained are successfully compared with simpliflied models but display discrepancies when increasing the diameter-to-length ratios since the influence of higher order modes and dispersion augments. Paper D develops an effective waveguide model for a pre-compressed cylindrical vibration isolator within the audible frequency domain at arbitrary compressions. The original, mathematically arduous problem of simultaneously modelling the preload and frequency dependence is solved by applying a novel transformation of the pre-strained isolator into a globally equivalent homogeneous and isotropic configuration enabling the straightforward application of a waveguide model to satisfy the boundary conditions. The results obtained present good agreement with the non-linear finite element results for a wide frequency range of 20 to 2000 Hz at different preloads. / QC 20101001

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