"uuid","repository link","title","author","contributor","publication year","abstract","subject topic","language","publication type","publisher","isbn","issn","patent","patent status","bibliographic note","access restriction","embargo date","faculty","department","research group","programme","project","coordinates"
"uuid:d1e1ccd3-0145-4053-bc7c-8ead2cc29b9b","http://resolver.tudelft.nl/uuid:d1e1ccd3-0145-4053-bc7c-8ead2cc29b9b","The effect of the yield to tensile strength ratio on stress/strain concentrations around holes in high-strength steels","Obers, Siemen F.P.M. (Student TU Delft; Huisman Equipment BV); Overal, Jaap J. (Huisman Equipment BV); Wong, W.J. (TU Delft Ship Hydromechanics and Structures); Walters, C.L. (TU Delft Ship Hydromechanics and Structures)","","2022","Application of high-strength steels in the maritime and offshore industry is currently limited by rules governing the ratio of the yield to tensile strength (the Y/T ratio). To better understand the physical basis for these rules, the nature and extent of the plastic stress/strain field in the vicinity of a stress concentration (a circular hole) in a structure made from high-strength steel are analyzed. This is done through analytical models of the stress field and the extent of plasticity in the vicinity of a hole based on classical methods. These analytical methods are validated through FEA models that are in turn validated by published experimental data. This paper concludes that a high Y/T ratio leads to a lower plastic SCF and a higher local strain in the vicinity of a hole. The extent of the plastic zone is not affected by different values of Y/T ratio for different values of σnom/σy.","Elasto-plastic; SCF; Ultra high-strength steels; Y/T","en","journal article","","","","","","","","","","","Ship Hydromechanics and Structures","","",""
"uuid:0ca8c448-dbbf-437f-bb9a-a44eb7c78ff1","http://resolver.tudelft.nl/uuid:0ca8c448-dbbf-437f-bb9a-a44eb7c78ff1","The effect of the yield to tensile strength ratio on the stress field in stress/strain concentrations around holes in steel structures","Obers, Siemen (TU Delft Mechanical, Maritime and Materials Engineering)","Walters, C.L. (mentor); Jiang, X. (graduation committee); Wong, W.J. (graduation committee); Overal, Jaap (mentor); Romeijn, Eric (mentor); Delft University of Technology (degree granting institution)","2021","The aim of this thesis is to determine the influence of the Y/T, yield to tensile strength, ratio on the stress fields of high strength steels. This is relevant to the offshore industry as regulations restrict the use of steels with a high yield to tensile strength ratio, which is a characteristic of high-strength and
ultra high-strength steels. Identifying the influence of these parameters on behavior could lead to a scientific underpinning and review of the rules. The focus of this thesis is on stress concentrations at circular cutouts under uniform tension. The local stress and strain was found, which could be used to
assess the risk of strain localization and fracture.
Analytical models of Stowell, Neuber and Irwin are used to establish new relationships between the Y/T ratio and the stress field. The analytical methods of Stowell and Neuber were able to account for strain hardening, while the Irwin analytical relationship only provides a elastic-perfectly plastic solution. Besides the stress field, an analytical formulation for the local strain based on Stowell’s theory is also established.
Numerical simulations were carried out for S690, S960, and S1100 materials. The numerical material models are later used in the research to validate analytical approaches. Also, an infinite plate approach is applied to the specimens by scaling the ligaments of the specimens by a factor of 6.
A parametric study has been carried out to gain insights into the influence of the governing parameters in relation to local strain. The parameters studied are the Y/T, yield strength, strain hardening exponent, and strength coefficient. Each parameter is varied separately.
The main conclusions are that a high Y/T ratio causes a slight decrease in plastic stress concentration factor, resulting in a slight increase in local strain. The strain hardening exponent shows the same trend, but the changes are even less significant. The yield strength and strength coefficient have no effect on the stress concentration factor or local strain. None of the parameters show any influence on the extent of the plastic zone of the material.","SCF; Elasto-plastic; Strain; Stress; Y/T","en","master thesis","","","","","","","","","","","","","",""