Endre søk
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Microstructure based modelling of ductile fracture in quench-hardenable boron steel
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
2015 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Reduction of fuel consumption and emissions by vehicle weight minimization constitute a major driving force for the development of new materials and manufacturing processes in the automotive industry. Simultaneously formed and quenched boron steel components have higher strength to weight ratio than conventional mild steel components. Additionally, hot formed components can be tailored to have regions with lower strength and higher ductility, improving their crash performance. This is often realized via dierential in-die cooling rates, thus yielding a variable microstructure compositiongiving rise to distributed mechanical properties. Predicting the performance envelopes of these types of components poses some challenges in terms of constitutive modelling, due to the dierential material composition and mechanical properties. Moreover, fractureinitiation is often a limiting design factor. This thesis aims to contribute to the constitutive and ductile fracture modelling of quench-hardenable boron steels, with reference to microstructure composition and hence process history. Modelling techniques which in an approximate manner can estimate the eective material properties based on the properties of the constituents in combination with ductile fracture models are presented.Computational issues concerning numerical nite element modelling of material instabilities are also addressed, essentially via two dierent methods. Introducing a discretization dependent parameter in the constitutive description, or by kinematic enhancements with respect to the localization problem. Both aim to reduce mesh sensitivity and provide improved predictions of post-instability response with industrially relevant mesh sizes.Additionally, an experimental investigation on the ow and fracture properties of boron steel, with a comprehensive range of dierent microstructure compositions, is presented. A full-eld measurement technique enabled the direct evaluation of mechanical properties and fracture relevant data from tensile tests. These results have supported the establishment of models and enabled their calibration, and they provide further insight to the inuence of microstructure and processing conditions on the ductile fracture properties. Comparisons between simulations and experiments indicate that useful predictions of the overall hardening behaviour and fracture elongations can be obtained by the suggested microstructure based modelling approach.

sted, utgiver, år, opplag, sider
Luleå tekniska universitet, 2015.
Serie
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
HSV kategori
Forskningsprogram
Hållfasthetslära; Centrumbildning - Centrum för högpresterande stål (CHS)
Identifikatorer
URN: urn:nbn:se:ltu:diva-26413Lokal ID: e2641fd3-338b-4b1e-9b1d-6abf91a2c76eISBN: 978-91-7583-262-3 (tryckt)ISBN: 978-91-7583-263-0 (digital)OAI: oai:DiVA.org:ltu-26413DiVA, id: diva2:999575
Merknad

Godkänd; 2015; 20150219 (ricost); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Rickard Östlund Ämne: Hållfasthetslära /Solid Mechanics Avhandling: Microstructure Based Modelling of Ductile Fracture in Quench-Hardenable Boron Steel Opponent: Professor Michael Worswick, Dept of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario, Canada Ordförande: Professor Mats Oldenburg, Avd för Material- och solidmekanik, Institutionen för Teknikvetenskap och matematik, Luleå tekniska universitet, Luleå. Tid: Fredag 17 april kl 10.00 Plats: E231, Luleå tekniska universitet

Tilgjengelig fra: 2016-09-30 Laget: 2016-09-30 Sist oppdatert: 2019-03-29bibliografisk kontrollert

Open Access i DiVA

fulltekst(16494 kB)213 nedlastinger
Filinformasjon
Fil FULLTEXT01.pdfFilstørrelse 16494 kBChecksum SHA-512
1d6fd1cc3d84fb44f93610106d8a30d44c372bcbcf8d2acb7d7dd0da182c0354db095c3e71c80a597d39de560ab2911fe72161e67cb274ecb95c7d752838cc3e
Type fulltextMimetype application/pdf

Søk i DiVA

Av forfatter/redaktør
Östlund, Rickard
Av organisasjonen

Søk utenfor DiVA

GoogleGoogle Scholar
Totalt: 213 nedlastinger
Antall nedlastinger er summen av alle nedlastinger av alle fulltekster. Det kan for eksempel være tidligere versjoner som er ikke lenger tilgjengelige

isbn
urn-nbn

Altmetric

isbn
urn-nbn
Totalt: 624 treff
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf