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dc.contributorDepartment of Mechanical Engineeringen_US
dc.creatorWang, Chengyang-
dc.identifier.urihttps://theses.lib.polyu.edu.hk/handle/200/6554-
dc.languageEnglishen_US
dc.publisherHong Kong Polytechnic University-
dc.rightsAll rights reserveden_US
dc.titleInvestigation of ductile fracture in microforming via experiment and FE simulationen_US
dcterms.abstractBecause science and technology are developing extremely fast, especial1y the rapid progress of electronic industry and micromachine, microparts are highly demanded in the last decade and their technical requirements are higher and higher. Nowadays, the microforming technology has been partially used in electronic industry for producing the microparts like micro screws, contact springs and IC socket etc. With the continuous development of technologies, applied fields of microforming are rapidly extended to machinery, chemical industry, aerospace, biology, etc, and its status is more and more important in these fields. Metal forming is a traditional and promising industry because of its high productivity, high material usage and good mechanical properties. But when the deformation processes are scaled down to micro-scale from conventional macro-scale, the deformation propertied of material changes, since the ratio between the dimensions of a part and parameters of the microstructures or surface changes with miniaturization. This is the so-called size effects, which prevent the transfer of knowledge about design and development from macro- to micro-forming. Therefore, it is necessary to investigate the size effect phenomena. In this thesis, Al-alloy cylinder billets with diameter from 2 mm to 0.5 mm were prepared. The size effect was investigated mainly from material behavior and scatter. The occurrence of ductile fracture is often a limiting factor in metal forming processes. Prediction of ductile fracture initiation allows prior modification of the process, which can result in a defect-free final product with financial savings. In this thesis, different shape and geometry specimens in micro-scale were prepared. The specimens were upset to investigate the fracture strain and fracture location. The commercial software DEFORM was used to simulate the forming progress. Six different criterions were built-in in the FE-simulation. The criterions were evaluated to get the most accurate one for Al-alloy.en_US
dcterms.extentxv, 122 leaves : ill. (some col.) ; 30 cm.en_US
dcterms.isPartOfPolyU Electronic Thesesen_US
dcterms.issued2012en_US
dcterms.educationalLevelAll Masteren_US
dcterms.educationalLevelM.Sc.en_US
dcterms.LCSHMetals -- Microstructure.en_US
dcterms.LCSHMetals -- Fracture.en_US
dcterms.LCSHMetals -- Ductility.en_US
dcterms.LCSHHong Kong Polytechnic University -- Dissertationsen_US
dcterms.accessRightsrestricted accessen_US

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Please use this identifier to cite or link to this item: https://theses.lib.polyu.edu.hk/handle/200/6554