9 results
Now showing1 - 9 of 9
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Development and validation of a local fatigue design concept for welded joints in offshore structures subjected to multi-axial and variable loading(American Society of Mechanical Engineers (ASME), 2026-06); ; ; ; Fatigue assessment of welded maritime structures is vital for safe, cost-effective offshore design. Conventional methods struggle with complex loading, variable amplitudes, and thick sections, often leading to overly conservative designs. In the joint industry research project SMATRA, a novel local approach combining notch stress analysis and fracture mechanics was developed, accounting for weld geometry, post-weld treatments, and multi-axial loading. By integrating 3D surface scans, automated FEM modeling, and a two-phase life prediction model (initiation and growth), prediction accuracy improved by 24–77% over IIW, Eurocode 3, and FKM standards. Validation on small-scale specimens and a full-scale double-Y-joint confirmed accurate crack initiation prediction. A practical design tool reduced assessment time by 80% and enabled seamless workflow integration. Material savings exceeded 25% in weld volume and plate thickness while maintaining safety. The project outcomes enable more efficient, safe, and sustainable offshore structures and establishes a foundation for industrial standardization of local fatigue assessment methods in the offshore industry.Publicationtype: Conference Paper19 2 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Fatigue behavior of thermal cut edges in normal- and high-strength steel: effect of defined post-processing treatment(Springer, 2025-09-08); ; ; ; Within ships or maritime structures, plate edges are an important detail for the strength and fatigue assessment. Large openings such as hatches on container vessels or windows on cruise ships lead to a stress concentration, which has to be considered for strength calculation. These openings within steel plates are generally manufactured by thermal cutting processes. The recommendations regarding fatigue design by the IIW and classification societies for the structural behavior of these details are limited to general design categories using the nominal stress approach. In addition, no strict differences in cutting technologies and edge treatments such as grinding are taken into account. The aim of this investigation is to present the potential of a defined edge treatment for thermal cut edges on the fatigue performance. Therefore, fatigue tests with constant amplitudes were carried out and the specimens are characterized by identifying important properties such as roughness and hardness. This paper describes the fatigue behavior of thermal cut edges made of structural steel plates with different thicknesses from 5 to 25 mm including steel grades from S235 up to S690. All specimens were manufactured in an acceptable and comparable quality range according to ISO 9013, quality level 2, and have been treated with a defined chamfer to compare the influences of cutting processes and yield levels. Previous studies already indicated a beneficial effect regarding fatigue strength of thermal cut edges using higher strength steels, but the results were not clearly in line to describe the behavior sufficiently. This study demonstrates and confirms that material effects and a targeted post-treatment have a beneficial impact on the fatigue behavior of thermal cut edges. A continuous increase in the achieved stress ranges was observed with increasing steel strength. Based on the observations made, an approach for predicting the achievable fatigue strength is presented, taking surface roughness and material strength into account.Publicationtype: Journal Article39 28 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Yield Strength and Thickness Effect on Fatigue Strength of Thermal Cut Plate EdgesThe increasing size of container vessels is accompanied by an increase of plate thicknesses as well as the extensive use of higher tensile strength steels. For large plate thicknesses as well as high yield strengths, the influence of these parameters on fatigue strength of thermal cut plate edges is not well validated. This paper describes results based on fatigue tests for specimens with yield strengths of 355 to 460 MPa and plate thicknesses of 25 to 80 mm. The specimens were fabricated using gas and plasma cutting as well as usual post-treatment methods. The objective of the investigations was to verify and, if suggested by the results, to modify the current fatigue assessment procedures for thermal cut plate edges.Publicationtype: Conference Paper35 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Fatigue performance of aluminum alloy EN-AW 5083 cut edges produced by abrasive water jet and laser cutting(2023-04); ; ; ; Diniz e Castro, J.The application of aluminum alloys within the maritime industry is very common for hull structures of smaller vessels and lightweight constructions such as deck housings and other superstructure elements. Besides welded details, the geometry of cut-outs and openings within the structure leads to stress concentrations that could be considered critical for the fatigue behavior. These openings are in general cut by thermal processes or waterjets. In the recommendations and class regulations for fatigue design of cut edges made of aluminum alloys, the amount of available guidelines for these details is very limited. The recommendations by IIW include only one design category of cut edges for the nominal stress approach. In addition, no differentiation is made regarding cutting techniques and qualities, as it is done for steel, as well as not for edge treatments such as grinding. This paper describes the fatigue testing of different specimen series cut out by laser and abrasive water jet (AWJ). All specimen bodies are made out of aluminum alloy EN-AW5083 plate material with a thickness of 4 or 5 mm.Publicationtype: Conference Paper29 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Fatigue strength of AH36 thermal cut steel edges at sub-zero temperatures(Multidisciplinary Digital Publishing Institute (MDPI), 2023-02-04); ; ; ; Cruise ships or yachts that operate in areas with seasonal freezing temperatures have large openings in the outer shell. Those are thermal cut edges, and they are exposed to very low temperatures. From fatigue crack growth testing of base materials, it is known that low temperatures can accelerate the crack growth, which may reduce the fatigue life of a structure. However, the current guidelines and rules of classification societies do not provide design curves for the fatigue assessment of thermal cut steel edges at sub-zero temperatures. Therefore, fatigue tests of thermal cut edges are conducted at −20° C and -50° C as well as at room temperatures for reference. The specimens are plasma-cut and tested in a temperature chamber under uniaxial loading with a resonant testing machine. The test results are statistically evaluated using linear regression and the maximum likelihood method. The results show that the fatigue strength at sub-zero temperatures is significantly higher compared to room temperature. The test results of this study indicate that sub-zero temperatures down to −50° C do not seem to cause a reduced fatigue life of thermal cut steel edges.Publicationtype: Journal ArticleScopus© Citations 1 87 106 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Fatigue strength of AH36 thermal cut steel edges at sub-zero temperaturesPublicationtype: Conference Paper45 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , The influence of edge treatment on fatigue behavior of thermal cut edges(American Society of Mechanical Engineers (ASME), 2022-06); ; ; ; Thermal cut edges can be found in most maritime structures, e.g. in window openings or hatch corners on ships. It is very common to treat free plate edges by grinding or sandblasting due to fatigue and coating requirements. The aim of this study is to review the fatigue behavior of typical treatment methods. Within this study several fatigue tests are performed to outline the influence of treatment methods used for different steel grades, plate thicknesses and cutting processes. Especially the influence of the local edge geometry caused by treatment like grinding or milling is not covered by fatigue rules and guidelines like Eurocode or IIW. Also, the influence of yield strength is not considered by these regulations. Only in shipbuilding a fatigue bonus for high strength steels is given. However, these rules are based on older data and an update is requested by ship building industries. For the investigation shipyards and partners from other industries produced a big number of specimens for fatigue tests. Steel grades are from S235 to S460. Surface roughness as well as local treatment geometry are well documented. In addition, hardness as well as residual stress measurements were performed. Finally fatigue tests were done. Overall goal of the study is to present applicable FAT curves to be used for fatigue assessment.Publicationtype: Conference Paper50 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , 610 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Comparison of fatigue strength of post-weld improved high strength steel joints and notched base material specimens(2018-04-30); ; ; ; Fricke, WolfgangKeels of high-performance sailing yachts are highly stressed parts of the hull structure. Such keels are either milled or are welded hollow profiles. Recently a trend towards using high strength steel to manufacture keels is observed. While the fatigue strength of the parent material increases linearly with yield strength, it is independent of yield strength after welding. This problem can be overcome by post-weld improvement of the local weld geometry. Fatigue test results of the critical weld detail made from S900 steel are compared in welded state and after weld toe grinding. Additional tests of the same detail made from S355 steel, are performed. Moreover, tests of the notched parent material corresponding to a milled keel are presented. The fatigue strength of the grinded specimens was 2.2 times larger than in as-welded condition. The notched base material specimens act as an upper bound S-N curve for the post-weld improved specimens.Publicationtype: Journal Article246