The influence of presumed border conditions on FEM thermal analysis results based on the example of an LNG tank support saddle

Abstract

The growing accessibility of CAE environments has made FEM more egalitarian, calling into question the reliability of some analyses. This paper aims to investigate the influence of some popularly taken assumptions on results of FEM thermal analyses on the example of a LNG tank support saddle. The temperature distribution of that structure is of interest since the classification societies require that the temperature of construction materials should not exceed allowed service conditions. THE GEOMETRYGeometric model of the tank support saddle is shown at Figure 1. In order to build a cost effective structure, the tank saddle includes a polymer layer (Grudziński 2014) used as an insulation. The order and thickness of layers is shown at detail view B (Fig. 1). The overall dimensions of the tank support saddle, not including the deck, are 0.4 m × 1.4 m × 4.6 m. PRESUMING A TWO DIMENSIONAL TEMPERATURE FIELDTwo-dimensional models are often used in order to decrease the calculation time. Such a simplification is allowable if one of the overall dimensions of the concerned body is an order of magnitude smaller than the other dimensions, or if two opposite border surfaces are insulated. In other cases, a distortion in analysis results occur. A difference between 3D and 2D, evaluation is shown at Figures 2 and 3 on the example of a LNG tank support saddle.

Applying the Anticipatory Failure Determination at a Very Early Stage of a System’S Development: Overview and Case Study

“…The analysis presented is part of a larger project, and the system under evaluation is the result of the application of ARIZ for finding methods of reducing fuel consumption in ships. Searching for potential failure can be supported by means of specialised software such as the aforementioned Ideation Failure Analysis TM and Ideation Failure Prediction TM (Kaplan et al, 1999), as well as on the basis of different physical chemical, biological, geometrical, and even psychological effects (AULIVE, 2017;Bejger and Gawdzińska, 2011;Boratyńska-Sala, 2016;Oxford Creativity 2017;Pajor et al, 1999;Zaplata and Pajor, 2016;Zolkiewski 2013). The ranking of the identified failures can also be made using various methods, including in addition to the aforementioned assessment matrix, a weighted average as well as methods based on direct comparisons of failure-related values of individual assessments, and the importance of individual evaluation criteria.…”

Characteristics of Production Methods of Aluminium and Magnesium Matrix Composite Castings

“…The required operational properties combined with low specific weight are extremely beneficial and desirable in the design of almost every system and element of a modern vehicle. Therefore, it is widely understood that transport is the area where composites may find increasingly wider application [6,7,[13][14][15][16][17]. Table 2 presents existing or potential areas of use of composite materials in the widely understood transportation industry.…”

“…Table 2. Scope of application of metal composite materials in the transportation industry and the resulting advantages [3,4,6,7,[10][11][12][13][14][15][16][17] Tabela 2. Obszar zastosowań metalowych materiałów kompozytowych w przemyśle środków transportu oraz wynikające z tego korzyści [3,4,6,7,[10][11][12][13][14][15][16][17]…”

“…This is due to the need to meet the requirements that lead to obtaining the new material by means of a combination of at least two chemically distinct materials in such a way that, while maintaining an appropriate and permanent bonding of the components, a clear boundary between them is maintained and that the distribution of the reinforcing components throughout the matrix is as uniform as possible. The characteristics of the material obtained in such a way are determined by the volume fraction of the components and their physical and mechanical parameters[7]. Creation of a strong bond between two distinct components requires the use of high temperatures or very high pressure forces, or the combination of these two factors at the same time.…”

The Development of an Explosion Protection System in the Starting Air Manifold of a High Power Engine

“…Fires and explosions due to dynamic loads can lead to damage to the ship's components (Jambor et. al., 2018;Gawdzińska et al, 2017;Grabian et al 2008;Kwiecińska, 2015;Ulewicz and Novy, 2017;Zapłata and Pajor, 2016) and finally to its temporary decommissioning. The continued presence of this hazard is due to the complex multi-factorial nature of these explosions, including in particular their source of combustible material, such as (Chybowski and Grzebieniak, 2009c):  the ignition of fuel or cylinder oil which has penetrated from a specific cylinder system through a leaking starting valve during operation or during start-up if fuel has accumulated while the cylinder was idle;  the ignition of an excessive amount of lubricating oil that accumulated in the starting manifold, which entered there together with the air from the starting air compressor in the case of worn piston scraper rings of the compressor pistons or even as a result of the compressor suction of oil vapours located in the marine engine room environment;…”