Sitkeän murtuman tarkastelussa käytettiin Abaqus-elementtimenetelmäohjelmistoa, ja liitokset analysoitiin 3D-solidielementeillä. Liitoksia tutkittiin hyödyntämällä FE-analyysiä, sekä kokeellisia tutkimuksia. Työssä tutkitut liitostyypit ovat päittäisliitos, poikittainen ripa, sekä nuolilevyliitos. Nykyään suuri osa suurlujuusteräksen tutkimuksesta käsittelee väsymistä, mutta sen ohella myös liitoksien staattinen kestävyys ja hitsauksen aiheuttama perusaineen pehmeneminen ovat tärkeitä tutkimuskohteita. Tässä diplomityössä tarkastellaan suurlujuusteräksestä S960 tehtyjen hitsausliitoksien sitkeä- ja haurasmurtuma-alttiutta ja miten suunnittelulla voidaan parantaa liitoksien kestävyyttä. And the brittle fracture tendency of the joint can be estimated based on the stress intensity factors. Brittle fracture assessment indicates that stress intensity factors at weld toe can be obtained by means of notch stress concentration factors. When the width of the heat affected zone exceeds the specific limit, even rigid joint geometry cannot force the fracture to from heat affected zone to the base material, hence, the ultimate load and deformation capacities decrease. If the joint geometry is sufficiently rigid, that is, high local notch effect and high deformation constraint, the failure occurs only at the base material, thus, the deformation and load capacity is better than in situation, where the fracture occurs at heat affected zone. In brittle fracture assessment, Abaqus/XFEM software was used in order to define stress intensity factors at the weld toe.ĭuctile fracture assessment showed, that the joint geometry and the width of the heat affected zone are the most influential parameters on the ultimate capacity and the fracture mode of the joint. The geometries of the joints were varied, and for each model, the maximum deformation and load capacities were defined. In ductile fracture assessment, finite element software Abaqus is used, and the joints are analyzed by using 3D solid elements. The joints are studied by utilizing FE-analysis, and also experimental tests. The examined joint types in this thesis are butt weld joint, transverse attachment, and arrow plate joint. Nowadays the main emphasis of studies related to ultra-high strength steel is on fatigue, but also the ultimate static capacity and the softening effect caused by welding are important areas of interest. The effect of improved design on the ultimate capacity is also studied. In this thesis, ductile and brittle fracture capacities of welded joints made of ultra-high strength steel S960 are examined.

Stress concentration factor in abaqus