Study on Wave Load Prediction and Fatigue Damage Analysis of River-Sea-Going Ship

2018 ◽  
Author(s):  
Guohu Guo ◽  
Yiwen Wang ◽  
Jin Gan ◽  
Weiguo Wu ◽  
Yunling Ye
Keyword(s):  
Finite Element ◽  
Stress Response ◽  
Fatigue Damage ◽  
Response Spectrum ◽  
Container Ship ◽  
Stress Range ◽  
Wave Load ◽  
Fatigue Assessment ◽  
Cumulative Fatigue Damage ◽  
Distribution Of Stress

With the consideration of shipping efficiency and the limited conditions of the Yangtze River, flat and wide ship become the preferred type for River-Sea-Going ship. This kind of structure is adverse to the ship’s stiffness under longitudinal bending, transverse bending. And two-stage repeated loading brings to the fatigue assessment of the ship structure new uncertainties, so accurate cumulative fatigue damage is a matter of necessary. Based on the theory of three-dimensional potential flow, the hydrodynamic analysis of River-Sea-Going container ship under specific route is carried out. The hull motion and the load transfer function of each section are obtained. The finite element model is used to calculate the amplitude-frequency response Operator RAOs. The influence of special routes and speed factors are also considered. Based on the frequency domain spectral analysis method combined with the scatter diagram of E1 sea area, the characteristics of wave-induced load are analyzed under 10−7.5 probability level. The stress response spectrum and the short-term distribution of stress range are obtained by combining the structural stress response calculation with the whole ship finite element structure model. The long-term distribution of stress response spectrum and stress range is also obtained. The cumulative fatigue damage of River-Sea-Going container ship under the special route is evaluated by using the S-N curve recommended by the criterion. It can provide the basis for the fatigue assessment of the new type of River-Sea-Going container ship.

Research on the Random Vibration Cumulative Fatigue Damage Life Based on the Finite Element Analysis

2013 ◽  
Vol 300-301 ◽  
pp. 992-996
Author(s):  
Cheng Cheng Wang ◽  
Chuan Ri Li ◽  
Tian Ma
Keyword(s):  
Finite Element ◽  
Fatigue Damage ◽  
Simulation Analysis ◽  
Response Spectrum ◽  
Engineering Practice ◽  
Element Analysis ◽  
Element Simulation ◽  
Extreme Response ◽  
The Finite Element Analysis ◽  
Cumulative Fatigue Damage

Aiming at most of the aviation products are facing the problem of fatigue fracture in vibration environment, we analysis the structure of a bracket with ANSYS-Workbench, predict the life of the bracket by different ways, and compared with the testing result, then use the Fatigue damage spectrum (FDS) and Extreme Response Spectrum (ERS) to analysis expected results. The research not only ensure the accuracy of simulation analysis and life predict, but also make a dynamic supervision of product life process, promote the application of finite element simulation analysis in engineering practice.

scholarly journals A Comparative Study on Fatigue Damage using a Wave Load Sequence Model

2018 ◽  
Vol 3 (1) ◽  
pp. 160
Author(s):  
Luis De Gracia ◽  
Naoki Osawa ◽  
Hitoi Tamaru ◽  
Toichi Fukasawa
Keyword(s):  
Fatigue Damage ◽  
Weather Conditions ◽  
Wave Direction ◽  
Wave Load ◽  
Ship Routing ◽  
Fatigue Assessment ◽  
Speed Reduction ◽  
Weather Routing ◽  
Cumulative Fatigue Damage ◽  
Storm Model

Despite that ships get the approval of classification societies and structural members are designed to survive random environmental conditions for twenty or twenty-five years, fatigue crack damage still occurs. Nowadays, the operation based on weather routing programs has become important, not only to avoid adverse sea conditions that can cause damage, time loss or significant speed reduction but also to improve the crew safety. In this paper, S-N based fatigue assessment of a welded joint in an ocean going is performed. It is assumed that the ship sails following a planned route and a route based on weather conditions. Short sea sequences are generated by a storm model called “4G Storm Model”, proposed by one of the co-authors (De Gracia et al., 2017). Stress histories are generated considering the stochastical nature of the wave direction variation. Cumulative fatigue damage is performed following a classification society rule. Based on these results, the effect of ship routing and headings model on the S-N fatigue assessment is discussed. Keywords: Weather routing, fatigue, cumulative damage, storm model, wave sequence model.

Probabilistic Fatigue Assessment of a Mooring Line Based on Station-Keeping Trials in Ice

2021 ◽  
Author(s):  
Chana Sinsabvarodom ◽  
Bernt J. Leira ◽  
Wei Chai ◽  
Arvid Naess
Keyword(s):  
Fatigue Damage ◽  
Probabilistic Models ◽  
Full Scale ◽  
Mooring Line ◽  
Stress Range ◽  
Station Keeping ◽  
Probability Models ◽  
Line System ◽  
Fatigue Assessment ◽  
Rainflow Counting

Abstract The intention of this work is to perform a probabilistic fatigue assessment of a mooring line due to loads associated with the station-keeping of a ship in ice. In March 2017, the company Equinor (Statoil) conducted full-scale tests by means of station-keeping trials (SKT) in drifting ice in the Bay of Bothnia. The vessel Magne Viking was employed in order to represent a supply vessel equipped with a mooring line system, and the realtime loading during the full-scale measurement was recorded. The second vessel Tor Viking was serving as an ice breaker in order to maintain the physical ice management activities with different ice-breaking schemes, i.e. square updrift pattern, round circle pattern, circular updrift pattern and linear updrift pattern. The fatigue degradation corresponding to these different patterns were investigated. The peaks and valleys of the mooring tension are determined using the min peak prominence method. For the purpose of probabilistic fatigue assessment, the Rainflow-counting algorithm is applied to estimate the mooring stress range. Fatigue assessment based both on Rainflow counting and fitted probabilistic models were performed. For the latter, the stress range distributions from the observed data of mooring loads are fitted to various probability models in order to estimate the fatigue damage. It is found that the stress ranges represented by application of the Weibull distribution for the probabilistic fatigue approach provides results of the fatigue damage most similar to the Rainflow counting approach. Among the different scenarios of Ice management schemes, the circular updrift pattern provides the lowest magnitude of the fatigue degradation.

A Comparison of Direct Calculation Approaches Applied on the Fatigue Strength Assessment of a Panamax Container Ship

2012 ◽  
Author(s):  
Zhiyuan Li ◽  
Wengang Mao ◽  
Jonas W. Ringsberg
Keyword(s):  
Stress Response ◽  
Fatigue Strength ◽  
Fatigue Damage ◽  
Measurement Data ◽  
Direct Calculation ◽  
Container Ship ◽  
Calculation Methods ◽  
Strength Assessment ◽  
Strip Theory ◽  
Calculation Procedures

Today, it is common practice to carry out fatigue assessments of ship structures using direct calculation procedures. A direct calculation analysis of a ship’s fatigue strength involves hydrodynamic analysis, stress response evaluation followed by fatigue damage calculation. Many numerical codes are available for these types of analyses. They could yield different values in a fatigue life prediction because of the different degrees of complexity in the computation of the ship’s response. For example, hydrodynamic loads can be calculated using the strip theory or the panel method. The stress response to these loads can be computed using a beam theory or more advanced analyses, such as global and/or local finite element analyses. In a direct fatigue analysis for ship design, spectral methods have been dominating but there is a growing interest in time-domain fatigue damage calculation procedures. The objective of the current investigation is to compare four commonly used direct calculation methods against measurement data. The comparison is carried out by making a case study on a Panamax container ship on which full-scale measurements have been performed. The computational efforts involved in the application of the current direct calculation methods are compared and their applicability in ship fatigue design is discussed.

A Method for Fatigue Evaluation of Trimaran Cross Structure With the Influence of Slamming

2017 ◽  
Author(s):  
Zhe Li ◽  
Huilong Ren ◽  
Kai Jin
Keyword(s):  
Stress Response ◽  
Fatigue Strength ◽  
Fatigue Damage ◽  
Linear Response ◽  
Operating Conditions ◽  
Wave Load ◽  
Hull Structure ◽  
Non Linear ◽  
Slamming Load ◽  
Cross Structure

Slamming is a highly non-linear phenomenon between hull structure and wave. Due to the special structure of trimaran, the slamming mode is extremely different from that of traditional vessel. Besides bow emergence and enter, the slamming phenomenon of the out shell at the cross structure is also obvious. In conventional hull structure fatigue strength evaluation, the slamming load is usually not considered. However, the slamming problem is unavoidable at danger load cases, and the stress concentration of the trimaran cross structure is serious. So it is dangerous to ignore the existence of slamming in serious load cases when evaluating the structural fatigue strength. Therefore, it is necessary to study the contribution of slamming load to fatigue damage. In this paper, a practical method for calculating and analyzing is presented to consider the effect of slamming on the fatigue strength of the trimaran cross structure to ensure that the fatigue life of the structure is closer to the true value. According to the linear theory, the relative motion and relative speed of the hull in wave and the stress response of the wave load on the structure are calculated firstly. Then, the stress response of the non-linear out shell slamming force is calculated. The linear response and non-linear response are combined. And the stress response time history under the combined action of slamming and wave load are obtained. Finally, the fatigue damage of the structure under dangerous operating conditions is calculated by the rain flow counting method. And the contribution value of the slamming load to the structural damage degree is calculated. The paper will put forward some reference suggestions for fatigue study calculation and evaluation of Trimaran cross structure with the influence of slamming.

scholarly journals Representative Environmental Condition for Fatigue Analysis of Offshore Jacket Substructure

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5494
Author(s):  
Tsung-Yueh Lin ◽  
Yi-Qing Zhao ◽  
Hsin-Haou Huang
Keyword(s):  
Fatigue Damage ◽  
Environmental Conditions ◽  
Element Model ◽  
Computational Time ◽  
Wave Load ◽  
Sea State ◽  
Stress Signals ◽  
Cumulative Fatigue Damage ◽  
The Taiwan Strait

The 20-year cumulative fatigue damage of an offshore jacket substructure was estimated under the long-term local environmental conditions in the Taiwan Strait. Because of the nonlinearity of wave load for slender members of the structure, time-domain simulations of the dynamic finite element model were conducted for each sea state. By utilizing the Dirlik method to process the stress signals, the fatigue damages of joints were computed. Concerning the computational time, we propose a probability-based method of using a representative combination of environmental conditions in this study, which can considerably reduce the required number of evaluations prior to determining fatigue damage, thereby improving the process of preliminary design. The results show that only three sea states among 120 can represent 28% of the average damage ratio, and up to 17 sea states fully resolved the fatigue life.

Cumulative Fatigue Damage With Random Loading

1962 ◽  
Vol 84 (3) ◽  
pp. 403-408 ◽  
Author(s):  
R. R. Gatts
Keyword(s):  
Fatigue Damage ◽  
Stress Amplitude ◽  
Amplitude Distribution ◽  
General Concept ◽  
Time Function ◽  
Discrete Distributions ◽  
Random Loading ◽  
Linear Rule ◽  
Cumulative Fatigue Damage ◽  
Distribution Of Stress

A general concept of the accumulation of fatigue damage is applied where stress amplitude is a random time function with a specified amplitude distribution. A differential equation relating damage accumulation to the amplitude distribution of stress is derived. This equation is applicable to both continuous and discrete distributions. Solutions of the equation are used to predict life under random loading on the basis of constant amplitude S-N data. Such predictions are compared for both continuous and discrete stress amplitude distributions and found in better over-all agreement with the data than comparable predictions by the linear rule.

Fatigue Assessment of Aluminum Ship Details by Hot-Spot Stress Approach

2011 ◽  
Author(s):  
Ba˚rd Wathne Tveiten ◽  
Stig Berge ◽  
Xiaozhi Wang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Hot Spot ◽  
Fatigue Tests ◽  
Stress Range ◽  
Extrapolation Methods ◽  
The Finite Element Method ◽  
Hot Spot Stress ◽  
Fatigue Assessment ◽  
Modeling Techniques

This paper presents a robust methodology for fatigue assessment of aluminum ship details using a hot-spot stress range approach. A series of fatigue tests of a typical aluminum ship detail was carried out to obtain a design S-N curve. The test detail was analyzed by the finite element method (FEM) using several modeling techniques and element types. Recommendations are given on finite element modeling practice, extrapolation methods and design S-N curves.

Fatigue Assessment of Aluminum Ship Details by Hotspot Stress Approach

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Bård Wathne Tveiten ◽  
Stig Berge ◽  
Xiaozhi Wang
Keyword(s):  
Finite Element ◽  
Hot Spot ◽  
Experimental Tests ◽  
Fatigue Tests ◽  
Stress Range ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Hot Spot Stress ◽  
Fatigue Assessment ◽  
Modeling Techniques

This paper presents a robust methodology for fatigue assessment of aluminum ship details using a hot-spot stress range approach. A series of fatigue tests of a typical aluminum ship detail was carried out to obtain a design S–N curve. The test detail was analyzed by the finite element method using several modeling techniques and element types. The results from both experimental tests and finite element analysis are discussed. Recommendations on the procedure of fatigue assessment of aluminum ships including S–N curve to be used are also presented.

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