Global Strength Assessment of Trimaran Structure

2012 ◽  
Vol 538-541 ◽  
pp. 2860-2863 ◽  
Author(s):  
Khurram Shehzad ◽  
Hui Long Ren ◽  
Chun Bo Zhen ◽  
Asifa Khurram
Keyword(s):  
Structural Strength ◽  
Direct Calculation ◽  
Fe Analysis ◽  
Strength Analysis ◽  
Stress Concentrations ◽  
Strength Assessment ◽  
Analysis Technique ◽  
Current Design ◽  
Design Loads ◽  
Global Strength

This paper presents structural strength assessment of trimaran by global FE-analysis. Global strength analysis using the finite-element method is a powerful tool extensively used to design well-balanced and reliable sea going vessels. This analysis technique is particularly recommended in unconventional and new ship designs. Lloyd’s Register rules (LR Rules) for classification of trimaran are used to compute design loads and load cases. Global FE analysis is performed as per direct calculation procedure of LR Rules. Maximum stress concentration locations or hot spots corresponding to each load case are identified. The stresses induced in trimaran structure for all load cases are less than the maximum allowable stress. Furthermore, some modifications in current design are suggested to reduce the stress concentrations and hence to improve the structural strength.

scholarly journals Fatigue Strength Assessment of Trimaran Cross-Deck Structure Based on Spectral and Simplified Fatigue Method

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Chunbo Zhen ◽  
Tianlin Wang ◽  
Pengyao Yu ◽  
Liang Feng
Keyword(s):  
Transfer Functions ◽  
Three Dimensional ◽  
Stress Transfer ◽  
Direct Calculation ◽  
Fatigue Behaviour ◽  
Fatigue Analysis ◽  
Fe Analysis ◽  
Linear Potential ◽  
Wave Loads ◽  
Strength Assessment

In order to investigate the fatigue behaviour of trimaran cross-deck structural details, the spectral and simplified fatigue analysis approaches are proposed. In spectral fatigue approach, three-dimensional (3D) linear potential flow theory and global FE analysis are used for wave loads and stress transfer functions calculation; the stochastic spectral fatigue analysis is carried out considering the weighted wave headings factors. In simplified fatigue approach, based on the direct calculation procedure of LR rules, the evaluation of simplified fatigue loads and loading conditions are presented, and the stress ranges are obtained by global finite element (FE) analysis. Then the fatigue lives of a few hot spots are computed to demonstrate the application of the proposed method. The result shows that the method given in this paper has a good applicability. This study offers methodology for the fatigue analysis of trimaran cross-deck structure, which may be regarded as helpful references for structural design of these types of ships.

A Method for Ultimate Strength Assessment of Plates in Combined Stresses

2015 ◽  
Author(s):  
Shengming Zhang ◽  
Lei Jiang
Keyword(s):  
Ultimate Strength ◽  
Structural Engineering ◽  
Fe Analysis ◽  
Strength Analysis ◽  
Element Analysis ◽  
Simple Method ◽  
Strength Assessment ◽  
Industry Standards ◽  
Non Linear ◽  
Offshore Industry

It is becoming a normal practice in structural engineering, including ships and offshore industry, to perform non-linear finite element analysis to assess the structure’s capacity for design or evaluation purposes. However, experience has shown that the quality and accuracy of the non-linear FE analysis results are highly dependent on the person’s skills and analysis procedures used. In some cases, the results could lead to a wrong conclusion. Simplified method with good accuracy is still a preferred approach in design by the industry because it is simple and easy to use. However, even the method for the simple model, a plate under combined loads, has not been addressed completely because of its complexity. This paper has thus developed a simple method for the ultimate strength analysis of square plates under combined longitudinal and transverse compressive stresses. The method is fully validated with a systematic non-linear FE analysis results. The paper has also compared the methods from the industry standards BS5400 and DIN18800. Analysis examples are also provided in the paper for reference and discussions.

Global Strength Assessment for Semi-Submersible Column After Supply Vessel Collision Accident

2009 ◽  
Author(s):  
Zhiqiang Hu ◽  
Jianmin Yang ◽  
Longfei Xiao ◽  
Xiaomei Yan
Keyword(s):  
Direct Calculation ◽  
Finite Element Models ◽  
Sea State ◽  
Distinctive Character ◽  
Strength Assessment ◽  
Structure Damage ◽  
Collision Zone ◽  
Global Strength ◽  
Collision Force ◽  
Numerical Simulation Technique

The researches of the anti-collision characters of a semi-submersible column and its capability of surviving in severe sea state after collision accident are completed in the paper. Three collision cases are designed. A 5000 ton vessel hits the semi-submersible column in transversal, longitudinal and oblique direction. Numerical simulation technique is used to do the analysis, and anti-collision characters of the semi-submersible column are summarized by the curves of collision force vs. penetration, the energy absorption proportion and structural damages. It can be pointed out that the column show a distinctive character when the contact surface is large at the beginning of the collision. There is no rupture of outer shell, which means the column can sustain such kind of collision. Taking advantage of the direct calculation method with finite element models, the global strength of the semi-submersible is verified to assess the influence of structure damage by the collision on the semi’s survival capability in severe sea state. The structure damage caused by the collision is taken into consideration in the FE models. The code SESAM is used to do the calculation through the design wave method. Several assumptions are made to realize the comparison between collision cases. It is found that the collision influence is restricted within the scope of structural components around the collision zone. The collision damage caused by the hitting of 5000 ton vessel will not bring a serious threat to the global strength capability of the semi-submersible.

Practical Procedures for Technical and Economic Investigation of Ship Structural Details

1981 ◽  
Vol 18 (01) ◽  
pp. 51-68
Author(s):  
Donald Liu ◽  
Abram Bakker
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Analysis Techniques ◽  
Structural Problems ◽  
Analysis Technique ◽  
The Finite Element Analysis ◽  
Structural Details

Local structural problems in ships are generally the result of stress concentrations in structural details. The intent of this paper is to show that costly repairs and lay-up time of a vessel can often be prevented, if these problem areas are recognized and investigated in the design stages. Such investigations can be performed for minimal labor and computer costs by using finite-element analysis techniques. Practical procedures for analyzing structural details are presented, including discussions of the results and the analysis costs expended. It is shown that the application of the finite-element analysis technique can be economically employed in the investigation of structural details.

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