광대역 불규칙 하중에 의한 피로 손상도 추정 모델 개발

Title
광대역 불규칙 하중에 의한 피로 손상도 추정 모델 개발
Authors
박준범
Keywords
광대역불규칙하중에의한피로손상도추정모델개발
Issue Date
2011
Publisher
인하대학교
Abstract
As offshore structures normally operate in a specific location, they experience combined wide band random loadings from wind-driven sea waves generated by winds in the local area, which have short period, and swell coming from long distance with a long period. Besides, the interaction between mooring lines / riser to maintain a fixed location and hull motion by the waves create wide band random loadings. In case of containerships that have large open deck structure, their speed, size and length are increasing by the request of economic demands, which make a wide band random response when the natural period of the incoming waves meet that of the ship. This phenomenon is called springing, and there has been lots of research done to predict fatigue damage of wide band random loading for the fluid and structural aspects. This study has developed a new model to predict fatigue damage for the wide band random loading. To do this, a relevant procedure for random load generation and time increment is made for the reliability of generated random loadings. Resultant random loadings are generated though representative wide band spectrum examples. Associated stress range distributions and fatigue damage are taken by the rain-flow counting method. By using these outcomes, a new model has been developed. Also in order to verify the new model, several kinds of spectra have been used to compare the rain-flow counting distribution and fatigue damage of the model with those of other existing typical models and prove the superiority of the model.
Description
Contents Abstract i Nomenclature iii List of Figures viii List of Tables xi Contents xii Introduction 1 Motivation 1 State of the arts 3 Objective & Work scope 6 1. Statistical Characteristics and Random Process 9 1.1 Basic Elements of Probability 9 1.2 Stationary and Ergodic Random Process 10 1.3 Auto-correlation Function and Spectrum 13 1.4 Spectral Moments and Bandwidths 15 2. Fourier Transform and Time Domain Extraction 19 2.1 Fourier Transform 19 2.2 The Relationship between Fourier Transform and Spectrum 20 2.3 Fast Fourier Transform (FFT), Nyquist Frequency and Window Function 21 2.4 Time Domain Extraction 24 3. Rain-flow Counting Method 26 3.1 Rain-flow Counting Method 26 3.2 Rainflow Counting Algorithm 27 4. Spectral Fatigue Analysis on Ship Structural Members 31 4.1 S-N Curve 31 4.2 Damage Summing Methods for Initiation 34 4.3 Spectral Fatigue Analysis 35 5. State of arts on the Fatigue Damage Model 37 5.1 Fatigue Damage Models of Wide Band Spectrum 37 5.1.1 Narrow band Approximation 37 5.1.2 Wirsching and Light(1980) Model 38 5.2 Fatigue Damage Models of Bi-modal Spectrum 39 5.2.1 Jiao-Moan(1990) Method 42 5.2.2 Revised Jiao-Moan Model and Validation of the Assumed Spectral Moments 47 5.2.2.1 Ideal Bi-modal Spectra 49 5.2.2.2 Validation of the Assumed Spectral Moments 51 5.2.3 Sakai-Okamura(1995) Method 56 5.3 Rain-flow Counting Distribution Models of Wide Band Spectrum 57 5.3.1 Dirlik(1985) Model 57 5.3.1.1 MRR 59 5.3.1.2 Dirlik Model and its Fatigue Damage Equation 60 5.3.2 Zhao-Baker(1992) Model 61 5.3.3 Tovo-Benasciutti(2004) Model 62 5.4 Simple Summation Method, Combined Spectrum Method 63 5.4.1 Simple Summation Method 63 5.4.2 Combined Spectrum Method 65 6. Development of New Fatigue Damage Model 67 6.1 Procedure of Time Domain E
URI
http://dspace.inha.ac.kr/handle/10505/22747
Appears in Collections:
College of Engineering(공과대학) > Naval Architecture & Ocean Engineering(조선해양공학) > Theses(조선해양공학 석박사 학위논문)
Files in This Item:
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