Dae Kyeom Park

On the Crashworthiness of Steel-Plated Structures in an Arctic Environment: An Experimental and Numerical Study

Structural crashworthiness with regard to crushing and fracture is a key element in the strength performance assessment of ship collisions in the Arctic. The aim of this study is to investigate the crashworthiness characteristics of steel-plated structures subject to low temperatures that are equivalent to the Arctic environment. The effect of low temperatures on the material properties is examined on the basis of tensile tests. Crushing tests are undertaken on steel-square tubes subject to a quasi-static crushing load at both room and low temperatures. The crushing behavior of the square tubes in this test is compared with ls-dyna computations. It is found that low temperatures have a significant effect on not only the material properties but also the crashworthiness of steel-plated structures in terms of mean crushing loads and brittle fracture. It is suggested that the collision-accidental limit state design of ships intended to operate in the Arctic region should be carried out by taking the effect of low temperatures into account.

Collision Tests on Steel-Plated Structures in Low Temperature

The aim of the study reported herein was to investigate the effects of low temperatures on the crashworthiness of steel-plated structures. A series of material tensile tests were performed to examine the material behaviors at low temperatures. Then, unstiffened steel-plated structure and stiffened steel-plated structure were collided with a cone-shaped drop object to estimate the crashworthiness of steel-plated structures. The material tensile test specimens and test structures were made of Polar class steel for ships and offshore structures which is a sufficient condition of the IACS requirements concerning Polar Class and Strength of Ships. The tests considered room and low temperatures relevant to an Arctic environment and a cryogenic condition. LS-DYNA nonlinear finite element simulations applying a practical approach of modeling techniques were performed to investigate the structural crashworthiness of the steel-plated structures numerically with results of material tensile tests.Copyright

Experimental assessment of the structural behaviour of aluminium helideck structures under static/impact loads

ABSTRACT Helidecks are used to access offshore installations for support and transport operations. The helideck and its supporting structure are critical safety elements due to their essential role in emergency evacuations. Therefore, the design of helideck structures should satisfy operational and accidental conditions. In current industrial practice, aluminium pancake designs tend to be based on a steel section profile with modifications. The design of aluminium helidecks should consider evaluations of structural safety and stability and comply with the design requirements of international codes. The aim of this study is to examine the structural behaviour characteristics of recently developed aluminium helideck structure through full-scale experiments investigations. The experimental results are documented and discussed with a current design code. The database and insights developed from the present work will be useful for the damage-tolerant design of aluminium structures and also for accidental and condition assessment or health monitoring of aluminium structures.

Effects of Low Temperature on ASTM A131: An Experimental and Numerical Study

The aim of this study was to investigate the effects of low temperatures on the material properties and crashworthiness of ASTM A131-type carbon steel. A series of tensile coupon tests and crushing tests on square tubes were performed in a liquid nitrogen cooled chamber to examine their material behavior and crashing behavior at a series of low temperatures under quasistatic conditions. The temperature conditions cover a cryogenic condition, the typical Arctic temperatures and room temperature.In the previous study, ASTM A500-type carbon steel is considered [13] and in present study the different grades of ASTM A131-type carbon steel for ships and offshore structures are considered, including Grades A, B and D of mild steel and Grades AH and DH of high tensile steel.The results of the tensile coupon tests showed an increase in the strength and in non-uniform fracture strain behavior in different grades and temperatures. Unstable crushing behavior and fractures were observed in the crushing tests. LS-DYNA nonlinear finite element method analyses were performed using reliable nonlinear finite element method modeling techniques to assess the structural crashworthiness of the materials at low temperatures.Copyright