1 Introduction This report presents results of a finite element analysis of ship frames subject t... more 1 Introduction This report presents results of a finite element analysis of ship frames subject to ice loads. The analysis covers the full range of frame behavior, from elastic, through yield, through the formation of initial mechanisms, through large deformations. The behaviors often include some local instabilities (buckling). The analyses continue until the total central deformation reaches about 10% of the frame span. The parameters include:• frame profile: Angle, Tee, Flat• frame span:• load length: patch (trans.), uniform (long'l)• web thickness:• ...
Abstract: This paper discusses an experimental ship structural research program that is well unde... more Abstract: This paper discusses an experimental ship structural research program that is well underway at Memorial University. The series of structural experiments is exploring the extreme plastic behaviour of full scale ship frames under intense local loads. The program began with tests on single frames with support from Transport Canada and with a view to validating of the frame limit state equations that were developed for the recently developed Unified Requirements for Polar Ships. The program was then expanded to include small ...
This paper describes experimental research conducted in part for the Ship Structures Committee pr... more This paper describes experimental research conducted in part for the Ship Structures Committee project # 1442 -Investigation of Plastic Limit States for Design of Ship Hull Structures. The research program consisted of a series of increasingly large experiments to investigate the plastic behavior of ship framing and grillages subject to lateral loads. The initial tests were conducted as single frames, fixed on the ends and loaded with a small patch load at either the center or near the ends, so that two forms of plastic collapse, bending and shear, could be investigated. After eight single frames were tested, the experiments proceeded to test two small grillages (3 frames attached to one plate panel) and then two large grillages (9 frames plus two stringers, attached to 3 plate panels, in a 6.8m x 2.46m panel). The experimental procedures, data sensors and the full range of results are described. Extensive ANSYS finite element analysis of frames has been conducted, and some comparisons are presented. The study found a number of interesting relationships between various buckling mechanisms (shear buckling, web compression buckling and tripping) and the overall plastic collapse. Implications for design, especially goal-based design, are discussed.
A recent review of ship structural regulations (Ship Structures Committee Project 1444) was aimed... more A recent review of ship structural regulations (Ship Structures Committee Project 1444) was aimed at clarifying best practice in regulations. The review focused on the hull girder and bottom structure. The majority of rules reviewed are formulated in terms of elastic stresses. It was expected that the review would be able to identify implicit as well as explicit factors of safety in either the load or strength formulations or both. However, no such factors of safety against yielding were found. While this was initially surprising, it leads to an interesting and useful insight into the question of why ships are able to operate safely. The best explanation is that ships, especially new ships, rely on small levels of plastic deformation to create a significant strength reserve, easily capable of withstanding not only the design loads, but overload conditions as well. Ductility is thus a crucially important material property for keeping ships safe. The complexity of plastic response raises the question of how best to reflect this issue in rules. This is especially important when considering the safety of aging ships. The issues of coating design, corrosion and fatigue deserve to be reexamined with a view to the effects of the plastic behavior during ageing.
1 Introduction This report presents results of a finite element analysis of ship frames subject t... more 1 Introduction This report presents results of a finite element analysis of ship frames subject to ice loads. The analysis covers the full range of frame behavior, from elastic, through yield, through the formation of initial mechanisms, through large deformations. The behaviors often include some local instabilities (buckling). The analyses continue until the total central deformation reaches about 10% of the frame span. The parameters include:• frame profile: Angle, Tee, Flat• frame span:• load length: patch (trans.), uniform (long'l)• web thickness:• ...
Abstract: This paper discusses an experimental ship structural research program that is well unde... more Abstract: This paper discusses an experimental ship structural research program that is well underway at Memorial University. The series of structural experiments is exploring the extreme plastic behaviour of full scale ship frames under intense local loads. The program began with tests on single frames with support from Transport Canada and with a view to validating of the frame limit state equations that were developed for the recently developed Unified Requirements for Polar Ships. The program was then expanded to include small ...
This paper describes experimental research conducted in part for the Ship Structures Committee pr... more This paper describes experimental research conducted in part for the Ship Structures Committee project # 1442 -Investigation of Plastic Limit States for Design of Ship Hull Structures. The research program consisted of a series of increasingly large experiments to investigate the plastic behavior of ship framing and grillages subject to lateral loads. The initial tests were conducted as single frames, fixed on the ends and loaded with a small patch load at either the center or near the ends, so that two forms of plastic collapse, bending and shear, could be investigated. After eight single frames were tested, the experiments proceeded to test two small grillages (3 frames attached to one plate panel) and then two large grillages (9 frames plus two stringers, attached to 3 plate panels, in a 6.8m x 2.46m panel). The experimental procedures, data sensors and the full range of results are described. Extensive ANSYS finite element analysis of frames has been conducted, and some comparisons are presented. The study found a number of interesting relationships between various buckling mechanisms (shear buckling, web compression buckling and tripping) and the overall plastic collapse. Implications for design, especially goal-based design, are discussed.
A recent review of ship structural regulations (Ship Structures Committee Project 1444) was aimed... more A recent review of ship structural regulations (Ship Structures Committee Project 1444) was aimed at clarifying best practice in regulations. The review focused on the hull girder and bottom structure. The majority of rules reviewed are formulated in terms of elastic stresses. It was expected that the review would be able to identify implicit as well as explicit factors of safety in either the load or strength formulations or both. However, no such factors of safety against yielding were found. While this was initially surprising, it leads to an interesting and useful insight into the question of why ships are able to operate safely. The best explanation is that ships, especially new ships, rely on small levels of plastic deformation to create a significant strength reserve, easily capable of withstanding not only the design loads, but overload conditions as well. Ductility is thus a crucially important material property for keeping ships safe. The complexity of plastic response raises the question of how best to reflect this issue in rules. This is especially important when considering the safety of aging ships. The issues of coating design, corrosion and fatigue deserve to be reexamined with a view to the effects of the plastic behavior during ageing.
Uploads
Papers by Mihailo Pavic