Christian Cabos

Wärtsilä · Information Management Technologies

Ship design and production activities are strongly driven by a very competitive environment as well as a reduction of time to market. The use of computer tools is thus strongly needed but is subject to many constraints. This article aims to provide the reader with a global view of this topic.

Traditionally, cargo hold and global strength analysis in ship design were dealt with two separate Finite Element (FE) models and analysis approaches. Requirements for model generation, in particular regarding mesh size, were significantly different. A new Advanced Whole Ship Analysis procedure was developed which is based on analyzing a global FE...

This paper describes an approach for hull strength assessment during ship life cycle using 3D models to describe hull condition (HC model) and strength (FE model). In addition to appropriate assessment methodologies of aging structures, an effective data exchange between the HC and FE models is required. The difficulty lies in the different abstrac...

The most costly part in the prediction of structure borne sound for a complex vehicle such as a ship lies in the build-up of the analysis model. Since often a finite element model is available from other structural mechanical analyses, NoiseFEM, the approach described in this paper, uses such a model as a starting point for an energy flow analysis....

Simulating global ship vibration can be split into three steps: firstly, the computation of the dry elastic vibration of the ship structure, secondly determination of the hydrodynamic pressures caused by a given time harmonic velocity distribution on the outer shell and thirdly, the solution of the coupled vibration problem by considering the inter...

Product Lifecycle Management (PLM) offers huge potential for process improvements and cost savings in the shipbuilding and shipping industries, due to the extremely short and highly collaborative ship development cycles and the long, maintenance-intensive life of the vessels. The challenge for the organizations involved in the ship lifecycle is to...

Simulating global ship vibration can be split into three steps: firstly, the computation of the dry elastic vibration of the ship structure, secondly determination of the hydrodynamic pressures caused by a given time harmonic velocity distribution on the outer shell and thirdly, the solution of the coupled vibration problem by considering the inter...

The vibration behavior of ships is noticeably influenced by the surrounding water, which represents a fluid of high density. In this case, the feedback of the fluid pressure onto the structure cannot be neglected and a strong coupling scheme between the fluid domain and the structural domain is necessary. In this work, fast boundary element methods...

Simulating global ship vibration can be split into three parts: firstly, the computation of the dry elastic vibration of the ship structure, secondly the determination of the hydrodynamic pressures caused by a given time harmonic velocity distribution on the outer shell and thirdly, the solution of the coupled vibration problem by considering the i...

Simulation of vibroacoustic behavior of submerged bodies necessitates dealing with fluid-structure coupled problems. In case of a high density of the fluid, the feedback of the acoustic pressure onto the structure cannot be neglected and a fully coupled system must be investigated. In this work, the finite element method (FEM) is used for the struc...

Performing inspections for Hull Condition Monitoring and Assessment as stipulated in IACS unified requirements and IMO's Condition Assessment Scheme (CAS) [5], [6] involves a huge amount of measurement data to be collected, processed, analysed and maintained. Information to be recorded consists of thickness measurements and visual assessment of coa...

Structural vibration transmission through semi-infinite plates was studied. The plates were assumed to be isotropic, thin and flat, and meet at a continuous line junction. The sound transmission coefficient was determined by considering a wave to be incident on the junction formed by the intersection of a number of semi-infinite plates. The amplitu...

The main structural elements that have to be considered for the prediction of structureborne noise propagation in ships are stiffened plates. For such structures, a method is proposed that combines ideas from diffusive energy propagation methods and statistical energy analysis. The resulting equations are solved with the help of the finite element...

The computational analysis of maritime structures naturally leads to various problems of fluid-structure interaction. We report on experience with the application of a coupled finite-boundary element method for the computation of the dynamic response of ships in water. In particular, we are concerned with the reliable computation of the so-called h...

In a research project performed jointly by Germanischer Lloyd, Hamburg and Institut fuer Technische Akustik (Prof. Heckl), Berlin (sponsored by the German Ministry for Research and Education) one of our aims was to develop a method for the prediction of structure bourne sound propagation using Finite Element models. The reason is, that often German...

For the approximate eigenvalues and eigenvectors obtained from a block Lanczos iteration, characterizations are given in terms of vectors of polynomials.It is proven that after r steps of block Lanczos with selfadjoint iteration matrix S, the application p(S)f of a matrix polynomial and the linear functional 〈v, q(S)f〉 can be evaluated exactly, if...

Für den Operator, der bei der Chebyshevschen Tau-Methode för lineare gewöhnliche Differentialgleichungen auftritt, wird mittels eines Integral-Operators eine Faktorisierung angegeben. Der erste Faktor dieser Faktorisierung hat eine beschränkte Konditions-Zahl und ist schwach besetzt, falls die Koeffizienten in der Differentialgleichung Polynome nie...

When using mode superposition in large applications, generally only relatively few approximate eigenmodes are linearly combined. Block Lanczos iteration is an efficient method of determining such modes. In this paper new a posteriori bounds are developed that estimate the error when approximating the exact result of mode superposition with a linear...

A posteriori error bounds for forced vibration calculations are presented which combine all steps of mode superposition into a single estimate. These techniques require that all Ritz vectors are used and that the input factors are included in the Lanczos starting block.

It is proved that the set τ of shifted Chebysheff-polynomials on [0,1] and the set υ of integrated Chebysheff-polynomials on [0,1] form a Schauder-basis of the space C∞[0,1] of infinitely differentiable functions on [0,1] endowed with the supremum-norm. Showing that the solution y of a linear first order initial value problem on [0,1] with polynomi...

Corrosion is one of the major issues for the structural condition of a vessel during its service life. In case of tankers and bulk carriers this aspect is even more crucial due to the exposure of the structure not only to salt water, but also to other abrasive substances in the cargo spaces. In order to monitor the condition of structural component...

With GL.ShipLoad, Germanischer Lloyd provides a user friendly computer application for the efficient load generation for global FE analyses of ship structures. The graphical user interface facilitates the convenient application of ship and cargo masses to the FE model. Hydrostatic and hydrodynamic computations are integrated into the program. GL.Sh...