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Yordan Garbatov - One of the best experts on this subject based on the ideXlab platform.

  • Experimental strength assessment of thin steel plates with a central elongated circular opening
    Journal of Constructional Steel Research, 2016
    Co-Authors: S. Saad-eldeen, Yordan Garbatov, C. Guedes Soares
    Abstract:

    Abstract This work assesses the ultimate strength of experimentally tested steel plates with a large central elongated circular opening, subjected to uni-axial compressive load. A series of experimental tests have been carried out on plates that were part of a real structure, which represents a scaled Midship Section of single hull tanker ship, tested in a corrosive environment in direct contact with seawater. One elongated circular opening shape with different sizes is analyzed and the effect of the opening size on the ultimate strength is investigated. The force–displacements relationships are presented and the dissipated energy is analyzed. Stress–strain relationships, resilience and toughness have been evaluated. The collapse modes are discussed and the ultimate strength has been compared with recently published studies showing a good agreement in the trend.

  • Reliability of Corrosion Protected and Maintained Ship Hulls Subjected to Corrosion and Fatigue
    Journal of Ship Research, 1999
    Co-Authors: C. Guedes Soares, Yordan Garbatov
    Abstract:

    A formulation is presented for the assessment of the reliability of a ship hull with respect to failure of the longitudinal members as a result of fatigue and corrosion. The model allows for the existence of multiple cracks and it accounts for the crack growth process. The Midship Section modulus is described by a stochastic process. A new model is presented for the effect of corrosion, which is a time-dependent process with two stages. In the first one, there is no corrosion due to the existence of coating protection. Upon failure of the protection system, general corrosion decreases plate thickness and affects the Midship Section modulus. The inspection is modeled as a random process. One repair policy is considered in the example, which consists of plate replacement when its thickness reaches 75% of the original thickness. The time-dependent degrading effect of corrosion and crack growth are modeled as a random process also. The reliability is predicted by a time variant formulation and the effects of maintenance actions in increasing the reliability are shown. The sensitivity of the reliability estimates with respect to several parameters is also studied. The formulation has been applied to a tanker.

  • Fatigue reliability of the ship hull girder
    Marine Structures, 1999
    Co-Authors: C. Guedes Soares, Yordan Garbatov
    Abstract:

    A formulation is presented for the assessment of the reliability of a ship hull with respect to fatigue failure of the longitudinal members. The model allows for the existence of multiple cracks both in the stiffeners and in the plating and it models the crack growth process. The effect of the cracks in decreasing the Midship Section modulus is quantified as a function of time and the resulting reliability is quantified. The sensitivity of the reliability estimates with respect to several parameters is also studied.

  • Reliability of maintained ship hulls subjected to corrosion and fatigue under combined loading
    Journal of Constructional Steel Research, 1999
    Co-Authors: C. Guedes Soares, Yordan Garbatov
    Abstract:

    A formulation is presented for the assessment of the reliability of longitudinal members of a ship hull as a result of fatigue and corrosion under combined loading. The model allows for the existence of multiple cracks and it accounts for the crack growth process. The time dependent degrading effect of corrosion and crack growth on the Midship Section modulus are modelled as random processes. The reliability is predicted by a time variant formulation and, using a two-failure criterion, the effects of maintenance actions in increasing the reliability are shown. The sensitivity of the reliability estimates with respect to different loading combinations is also studied. The formulation has been applied to a tanker.

  • Reliability assessment of maintained ship hulls with correlated corroded elements
    Marine structures, 1997
    Co-Authors: C. Guedes Soares, Yordan Garbatov
    Abstract:

    This paper reviews the factors that affect the corrosion rate of the ship hull girder. It is shown that corrosion rates vary as a function of the location of the element in the structure, of the ocean area and type of ballast tank and steel. However, the corrosion rate in elements that are subjected to similar conditions is highly correlated. A time-variant formulation is proposed including the correlation between the corrosion rates in neighbouring elements in modelling the degrading effect that corrosion has on the reliability of ship hulls. The effect of corrosion is represented as a time-dependent decrease of plate thickness that affects the Midship Section modulus. One repair policy was considered and the example results show the effect of plate replacement when its thickness reaches 75% of the original value. The results also illustrate how the limit value of the thickness in the repair criteria influences the reliability and the decision about repair actions. This is also shown for the effect of different corrosion rates, inspection intervals, and allowable stresses.

C. Guedes Soares - One of the best experts on this subject based on the ideXlab platform.

  • Experimental strength assessment of thin steel plates with a central elongated circular opening
    Journal of Constructional Steel Research, 2016
    Co-Authors: S. Saad-eldeen, Yordan Garbatov, C. Guedes Soares
    Abstract:

    Abstract This work assesses the ultimate strength of experimentally tested steel plates with a large central elongated circular opening, subjected to uni-axial compressive load. A series of experimental tests have been carried out on plates that were part of a real structure, which represents a scaled Midship Section of single hull tanker ship, tested in a corrosive environment in direct contact with seawater. One elongated circular opening shape with different sizes is analyzed and the effect of the opening size on the ultimate strength is investigated. The force–displacements relationships are presented and the dissipated energy is analyzed. Stress–strain relationships, resilience and toughness have been evaluated. The collapse modes are discussed and the ultimate strength has been compared with recently published studies showing a good agreement in the trend.

  • Reliability of Corrosion Protected and Maintained Ship Hulls Subjected to Corrosion and Fatigue
    Journal of Ship Research, 1999
    Co-Authors: C. Guedes Soares, Yordan Garbatov
    Abstract:

    A formulation is presented for the assessment of the reliability of a ship hull with respect to failure of the longitudinal members as a result of fatigue and corrosion. The model allows for the existence of multiple cracks and it accounts for the crack growth process. The Midship Section modulus is described by a stochastic process. A new model is presented for the effect of corrosion, which is a time-dependent process with two stages. In the first one, there is no corrosion due to the existence of coating protection. Upon failure of the protection system, general corrosion decreases plate thickness and affects the Midship Section modulus. The inspection is modeled as a random process. One repair policy is considered in the example, which consists of plate replacement when its thickness reaches 75% of the original thickness. The time-dependent degrading effect of corrosion and crack growth are modeled as a random process also. The reliability is predicted by a time variant formulation and the effects of maintenance actions in increasing the reliability are shown. The sensitivity of the reliability estimates with respect to several parameters is also studied. The formulation has been applied to a tanker.

  • Fatigue reliability of the ship hull girder
    Marine Structures, 1999
    Co-Authors: C. Guedes Soares, Yordan Garbatov
    Abstract:

    A formulation is presented for the assessment of the reliability of a ship hull with respect to fatigue failure of the longitudinal members. The model allows for the existence of multiple cracks both in the stiffeners and in the plating and it models the crack growth process. The effect of the cracks in decreasing the Midship Section modulus is quantified as a function of time and the resulting reliability is quantified. The sensitivity of the reliability estimates with respect to several parameters is also studied.

  • Interaction Equation for the Collapse of Tankers and Containerships Under Combined Bending Moments
    Journal of Ship Research, 1997
    Co-Authors: J.m. Gordo, C. Guedes Soares
    Abstract:

    The ultimate collapse of the Midship Section of tankers and container ships under combined vertical and horizontal bending moments is determined by an approximate method. That accounts for the load shortening contribution of each plate and stiffener assembly, thus being able to construct the moment-curvature relation for the hull girder. The method is applied to study five tankers and six container ships and the results are used to define an interaction formula proposed to account for the combination of the load effects for design purposes.

  • Reliability assessment of maintained ship hulls with correlated corroded elements
    Marine structures, 1997
    Co-Authors: C. Guedes Soares, Yordan Garbatov
    Abstract:

    This paper reviews the factors that affect the corrosion rate of the ship hull girder. It is shown that corrosion rates vary as a function of the location of the element in the structure, of the ocean area and type of ballast tank and steel. However, the corrosion rate in elements that are subjected to similar conditions is highly correlated. A time-variant formulation is proposed including the correlation between the corrosion rates in neighbouring elements in modelling the degrading effect that corrosion has on the reliability of ship hulls. The effect of corrosion is represented as a time-dependent decrease of plate thickness that affects the Midship Section modulus. One repair policy was considered and the example results show the effect of plate replacement when its thickness reaches 75% of the original value. The results also illustrate how the limit value of the thickness in the repair criteria influences the reliability and the decision about repair actions. This is also shown for the effect of different corrosion rates, inspection intervals, and allowable stresses.

Ho Jin Hwang - One of the best experts on this subject based on the ideXlab platform.

  • Mapping 2D Midship drawings into 3D structural models based on STEP AP218
    Geometric Modeling and Processing. Theory and Applications. GMP 2002. Proceedings, 2002
    Co-Authors: Ho Jin Hwang
    Abstract:

    The structural model for Midship Section is within the scope of STEP AP218. It supports to represent the ship structural models, but shipyards and classification societies exchange the information via 2D drawings. To convert the 2D information into the ship structure models of STEP AP218, we analyze the 2D Midship Section information of KR-TRAS of Korean Register of Shipping, and add the transverse members information. We also define the mapping table with mapping relationships between two data structures. With this mapping table we develop the translator for Midship Section. We visualize the translated 3D ship structure model using a STEP viewer. The ship structural model can be shared between different design departments, and used for the life cycle through design, analysis, and maintenance.

  • GMP - Mapping 2D Midship drawings into 3D structural models based on STEP AP218
    Geometric Modeling and Processing. Theory and Applications. GMP 2002. Proceedings, 2002
    Co-Authors: Ho Jin Hwang
    Abstract:

    The structural model for Midship Section is within the scope of STEP AP218. It supports to represent the ship structural models, but shipyards and classification societies exchange the information via 2D drawings. To convert the 2D information into the ship structure models of STEP AP218, we analyze the 2D Midship Section information of KR-TRAS of Korean Register of Shipping, and add the transverse members information. We also define the mapping table with mapping relationships between two data structures. With this mapping table we develop the translator for Midship Section. We visualize the translated 3D ship structure model using a STEP viewer. The ship structural model can be shared between different design departments, and used for the life cycle through design, analysis, and maintenance.

  • Mapping 2D Midship drawings into 3D structural models based on STEP AP218
    Proceedings - Geometric Modeling and Processing: Theory and Applications GMP 2002, 2002
    Co-Authors: Ho Jin Hwang, Soonhung Han, Yong Dea Kim
    Abstract:

    Standard for the exchange of product model data (STEP) AP218 has a standard schema to represent the structural model of a Midship Section. While its schema facilitate the exchange of ship structural models among heterogeneous systems, most shipyards and classification societies exchange information using 2D paper drawings. We propose a feature parameter input method to generate a 3D STEP model of a ship structure from 2D drawings. We have analyzed the ship structure information contained in 2D drawings and have defined a data model to express the contents of the drawing. We also developed a GUI for the feature parameter input. To translate 2D information extracted from the drawing into a STEP AP218 model, we have developed a shape generation library and have generated the 3D ship model through this library. The generated 3D STEP model of a ship structure can be used to exchange information between design departments in a shipyard as well as between classification societies and shipyards. © 2003 Elsevier Ltd. All rights reserved.

  • mapping 2d Midship Section into 3d structural models based on step ap218
    Journal of The Society of Naval Architects of Korea, 2001
    Co-Authors: Ho Jin Hwang
    Abstract:

    The structural model of Midship Section is within the scope of STEP AP218. It supports to represent the ship structure, but most of shipyards and classification societies exchange the information using 2D drawings at the present. To translate the 2D information into the ship structure model of STEP AP218, we analyze the 2D Midship Section information of KR-TRAS of Korean Register of shipping, and include the transverse members information with the 3D model. We also define the mapping table and the mapping relationships between two data structures. With this mapping table we develop the translator for the Midship Section, and visualize the translated ship structure model using a STEP viewer. The ship structure model can be used to exchange information between design departments, and through the lifecycle of design, analysis, and maintenance.

Ming Lv - One of the best experts on this subject based on the ideXlab platform.

  • Tooth flank feature analysis and study on grinding method of full edge gear honer
    International Technology and Innovation Conference 2009 (ITIC 2009), 2009
    Co-Authors: Xiuqing Zhang, Ming Lv
    Abstract:

    Tooth flank equation of full edge gear honer was deduced according to the principle of gear engagement. Some basic tooth flank features of full edge gear honer were obtained through calculating tooth flank coordinates, involute fitting to arbitrary end cross-Section and calculating modification relative to involute helicoid. The results showed that profile of full edge gear honer almost coincided with involute helicoid in Midship Section, but cross-Section profile from Midship Section to two ends showed that base circle changed gradually, axial shape is concave and anti-drum, and tooth flank of full edge gear honer could be regarded as involute helicoid which was modified. Grinding method of full edge gear honer was determined according these features, that is, tooth flank of imaginary rack was calculated through conjugate tooth flank of entir cutting honer, then tooth flank of imaginary rack is approached by cone grinding wheel, then the dressing parameters of grinding wheel and the adjusting parameters of machine tool were calculated, and the results showed that this method was feasible[1].

  • Tooth flank feature analysis and study on grinding method of full edge gear honer
    International Technology and Innovation Conference 2009 (ITIC 2009), 2009
    Co-Authors: Xiuqing Zhang, Ming Lv, Lin Ma
    Abstract:

    Tooth flank equation of full edge gear honer was deduced according to the principle of gear engagement. Some basic tooth flank features of full edge gear honer were obtained through calculating tooth flank coordinates, involute fitting to arbitrary end cross-Section and calculating modification relative to involute helicoid. The results showed that profile of full edge gear honer almost coincided with involute helicoid in Midship Section, but cross-Section profile from Midship Section to two ends showed that base circle changed gradually, axial shape is concave and anti-drum, and tooth flank of full edge gear honer could be regarded as involute helicoid which was modified. Grinding method of full edge gear honer was determined according these features, that is, tooth flank of imaginary rack was calculated through conjugate tooth flank of entire cutting honer, then tooth flank of imaginary rack is approached by cone grinding wheel, then the dressing parameters of grinding wheel and the adjusting parameters of machine tool were calculated, and the results showed that this method was feasible. (4 pages)

Mahiuddin Chowdhury - One of the best experts on this subject based on the ideXlab platform.

  • the changes in mean and variance of Midship Section properties due to uniform corrosion wear
    Ships and Offshore Structures, 2008
    Co-Authors: Mahiuddin Chowdhury
    Abstract:

    Abstract A typical Midship Section is represented by a deck, inner bottom, outer bottom, side shells and round bilge corners. As an example, angle bar stiffeners were used throughout and symmetric I-beams are placed as girders. Accurate expressions were developed for the Section properties of both stiffeners and then the Midship Section. The properties considered include cross-Sectional area, moment of inertias and Section modulus. The first order second moment (FOSM) approximation was used to derive the mean and standard deviation of the Midship Section properties. The changes in Section properties due to uniform corrosion wear are considered. The main focus of this article is to derive accurate empirical relationships for the mean and standard deviation of any given Midship Section as simple functions of corrosion loss. It has been observed that all geometric properties are linear functions of total corrosion loss, and there is a single constant relevant to the Section which specifies the property compl...

  • on the probability of failure by yielding of hull girder Midship Section
    Ships and Offshore Structures, 2007
    Co-Authors: Mahiuddin Chowdhury
    Abstract:

    Abstract Based on the first order second moment principles (FOSM) a detailed methodology has been developed to predict the failure probability of an idealized hull-girder mid-ship Section by yielding. The probability is related to the age of the ships when corrosion causes wear of the structural components. Three different corrosion models have been discussed. A numerical example is presented with full details.