Modellierung der Schädigung während der Warmumformung

Translated title of the contribution: Modelling of damage during hot forming

Guntram Rüf

Research output: ThesisDoctoral Thesis

Abstract

In the area of FE-simulation of hot working processes the software development increasingly comprises damage calculations for the description of the forming limit of complicated components and severely deformable materials. Within the scope of this work the applicability and the precision of macroscopic and microscopic damage models including the model of effective stresses is investigated by means of a commercial FE-program and an experimental database. In particular, the damage evolution in the nickel-based alloy 80A is studied. Most models show maximum damage for cylindrical specimens at the experimentally determined fracture site, but do not predict the correct fracture site for collar test specimens in an adequate precision. For all models excepting the model off effective stresses a lack in transferability of critical values to different testing conditions could be determined. Additionally, a semi-empirical grain structure model has been coupled to describe the materials softening by dynamic recrystallisation. With the onset of recrystallisation the summed up deformation, i.e. the effective plastic strain is reduced by recrystallisation and hence the damage evolution rate is decreased. In two different approaches the coupling of the stress-strain analysis with the damage calculation was established and compared with the uncoupled simulation.
Translated title of the contributionModelling of damage during hot forming
Original languageGerman
QualificationDr.mont.
Supervisors/Advisors
  • Buchmayr, Bruno, Assessor A (internal)
  • Pippan, Reinhard, Assessor B (internal)
Publication statusPublished - 2007

Bibliographical note

embargoed until null

Keywords

  • Damage Dynamic Recrystallization Hot forming Nickel-based superalloys Crack initiation

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