• Title/Summary/Keyword: fatigue Model

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The measured contribution of whipping and springing on the fatigue and extreme loading of container vessels

  • Storhaug, Gaute
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.6 no.4
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    • pp.1096-1110
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    • 2014
  • Whipping/springing research started in the 50'ies. In the 60'ies inland water vessels design rules became stricter due to whipping/springing. The research during the 70-90'ies may be regarded as academic. In 2000 a large ore carrier was strengthened due to severe cracking from North Atlantic operation, and whipping/springing contributed to half of the fatigue damage. Measurement campaigns on blunt and slender vessels were initiated. A few blunt ships were designed to account for whipping/springing. Based on the measurements, the focus shifted from fatigue to extreme loading. In 2005 model tests of a 4,400 TEU container vessel included extreme whipping scenarios. In 2007 the 4400 TEU vessel MSC Napoli broke in two under similar conditions. In 2009 model tests of an 8,600 TEU container vessel container vessel included extreme whipping scenarios. In 2013 the 8,100 TEU vessel MOL COMFORT broke in two under similar conditions. Several classification societies have published voluntary guidelines, which have been used to include whipping/springing in the design of several container vessels. This paper covers results from model tests and full scale measurements used as background for the DNV Legacy guideline. Uncertainties are discussed and recommendations are given in order to obtain useful data. Whipping/springing is no longer academic.

Fatigue life prediction for radial truck tires using a global-local finite element method

  • Jeong, Kyoung Moon;Beom, Hyeon Gyu;Kim, Kee-Woon;Cho, Jin-Rae
    • Interaction and multiscale mechanics
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    • v.4 no.1
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    • pp.35-47
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    • 2011
  • A global-local finite element modeling technique is employed in this paper to predict the fatigue life of radial truck tires. This paper assumes that a flaw exists inside the tire, in the local model. The local model uses an FEM fracture analysis in conjunction with a global-local technique in ABAQUS. A 3D finite element local model calculates the energy release rate at the belt edge. Using the analysis of the local model, a study of the energy release rate is performed in the crack region and used to determine the crack growth rate analysis. The result considers how different driving conditions contribute to the detrimental effects of belt separation in truck tire failure. The calculation of the total mileage on four sizes of radial truck tires has performed on the belt edge separation. The effect of the change of belt width design on the fatigue lifetime of tire belt separation is discussed.

Energy Ratio Factor and Phase Angle Based Fatigue Prediction Model for Flexible Pavements

  • Kim, Nak-Seok
    • Journal of the Korean Society of Hazard Mitigation
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    • v.11 no.2
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    • pp.75-80
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    • 2011
  • The main objective of this research is to develop fatigue prediction model for flexible pavements using energy ratio factor and phase angle. The two parameters are considered as fundamental properties of time and temperature dependent viscoelastic asphalt concrete materials. The energy ratio factor is defined as the ratio of the pseudo-total cumulative dissipated energy to the cumulative dissipated energy to failure during the test. The phase angle between the stress and strain ware signals stems from the intrinsic the dependent asphalt mixture behavior. The phase angle was computed and the relationship between the initial mixture stiffness and the initial phase angle is presented. As a result, fatigue prediction model for flexible pavements was proposed using intrinsic properties of viscoelastic asphalt concrete materials.

Prediction of Shearing Die Life for Producing a Retainer using FE Analysis (유한요소해석을 이용한 리테이너 전단 금형 수명예측)

  • Lee, I.K.;Lee, S.Y.;Lee, S.K.;Jeong, M.S.;Seo, P.K.;Lee, K.H.;Kim, B.M.
    • Transactions of Materials Processing
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    • v.24 no.4
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    • pp.264-271
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    • 2015
  • In the current study, a method was proposed to quantitatively predict the wear and fatigue life of a shearing die in order to determine an effective replacement period for the die. The shearing die model of a retainer manufacturing process was used for the proposed method of quantitative life prediction. The retainer is produced through shearing steps, such as piercing and notching. The shearing die of the retainer is carefully controlled because the dimensional accuracy of the retainer is critical. The fatigue life for the shearing die was predicted using ANSYS considering S-N curves of STD11 and Gerber’s equation. The wear life for the shearing die was predicted using DEFORM-3D considering the Archard’s wear model. Experimental shearing of the retainer was conducted to verify the effectiveness of the proposed method for predicting die life. The fatigue failure of the shearing die was macroscopically measured. The wear depth was measured using a 3D coordinate measuring machine. The results showed that the wear and fatigue life in the FE analysis agree well with the experimental results.

Fatigue Analysis of Bike Brake under Nonuniform Load (불규칙 하중을 받는 자전거 브레이크의 피로 해석)

  • Cho, Ja-Eung;Han, Moon-Sik
    • Transactions of the Korean Society of Automotive Engineers
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    • v.20 no.4
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    • pp.133-141
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    • 2012
  • This study investigates structural and fatigue analyses of bike brake. Maximum equivalent stress of the model of mountain bike is 4 times as much as the model of general bike at static analysis. In cases of mountain and general bikes, maximum damage frequency at load of 'SAE bracket history' with the severest change of load becomes as much as 16 times than the most stable load of 'Sample history' among the nonuniform fatigue loads. In case of mountain bike, the possibility of maximum damage becomes 3% at the load of 'Sample history' with the average stress of 0 to $-3{\times}10^4$MPa and the amplitude stress of 0 to $10^4$MPa. In case of general bike, the possibility of maximum damage becomes 3% at the load of 'Sample history' with the average stress of 0 to $-0.8{\times}10^4$MPa and the amplitude stress of 0 to $0.2{\times}10^4$MPa. This stress state can be shown as 5 to 6 times more than the damage possibility of 'SAE bracket history' or 'SAE transmission'. The analysis result of this study can be effectively utilized for the safe design of bike brake.

Structural Assessment of Container ships Considering Hydroelastic Responses (컨테이너선의 유탄성 응답을 고려한 구조강도 평가 기술)

  • Park, Jun Seok;Choi, Byung Ki;Choi, Ju Hyuck;Jung, Byoung Hoon
    • Special Issue of the Society of Naval Architects of Korea
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    • 2017.10a
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    • pp.80-87
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    • 2017
  • This paper is related to structural assessment considering the hydroelastic response of ultra large container ships, especially from whipping (bow or stern impacts) and from springing (resonance). In general, whipping contributes both to increased fatigue and extreme loading, while springing does mainly contribute to increased fatigue loading. To evaluate the hydroelastic response quantitatively with high accuracy, numerical code considering hydro-structure coupling was applied and fatigue strength of a 13,100 TEU class containership was verified. The segmented model test and full scale measurement were also needed to assess the effect of whipping and springing on the fatigue and extreme capacity in more realistic way and for verification of the numerical tools. With reference to class rule, fatigue assessment considering springing effect and extreme assessment considering whipping effect were introduced.

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A Study of the Relationship of Chronic Pain, Pain Coping, Fatigue, Self-esteem, and Depression in Elders (노인의 만성통증과 통증대처, 피로, 자아존중감 및 우울의 관계연구)

  • Chang Hae-Kyung;Sohn Jung-Nam;Cha Bo-Kyoung
    • Journal of Korean Academy of Fundamentals of Nursing
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    • v.13 no.1
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    • pp.86-95
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    • 2006
  • Purpose: This study was done to investigate the relationship among the variables, chronic pain, pain coping, fatigue, self-esteem, and depression in elders. Method: Data were collected by self-reported questionnaires from 270 older adults. Data analysis was done with SPSS 10.1 for descriptive statistics and a PC LISREL program for covariance structural analysis. Results: According to modified model, chronic pain was found to have a significant direct and total effect on pain coping. Chronic pain and pain coping were found to have a significant direct and total effect on fatigue. Chronic pain, pain coping and fatigue were found to have a significant direct and total effect on self-esteem. Chronic pain, pain coping, and self-esteem were found to have a significant direct effect on depression. Conclusion: This modified model is considered appropriate for explaining the relationship among chronic pain, pain coping, fatigue, self-esteem, and depression in elders. Also, the findings support the development of an intervention strategy to relieve chronic pain in elders.

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A Stochastic Analysis for Crack Growth Retardation Behavior and Prediction of Retardation Cycle Under Single Overload (단일과대하중하에서 피로균열진전지연거동 및 지연수명의 확률론적 해석)

  • Shim, Dong-Suk;Kim, Jung-Kyu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.23 no.7 s.166
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    • pp.1164-1172
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    • 1999
  • In this study, to investigate the fatigue crack retardation behavior and the variability of retardation cycles, fatigue crack growth tests were conducted on 7075-T6 aluminum alloy under single tensile overload. A retardation coefficient, D was introduced to describe fatigue crack retardation behavior and a random variable, Z to describe the variability of fatigue crack growth. The retardation coefficient was separately formulated according to retardation behavior which is composed of delayed retardation part and retardation part. The random variable, Z was evaluated from experimental data which was obtained from fatigue crack growth tests under constant amplitude load. Using these variables, a probabilistic model was developed on the basis of the modified Forman's equation, and retardation behavior and cycles were predicted under certain overload condition. The predicted retardation curve well agrees with the trend of experimental crack retardation behavior. And this model well predicts the scatter of experimental retardation cycles.

Probability analysis of optimal design for fatigue crack of aluminium plate repaired with bonded composite patch

  • Errouane, H.;Deghoul, N.;Sereir, Z.;Chateauneuf, A.
    • Structural Engineering and Mechanics
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    • v.61 no.3
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    • pp.325-334
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    • 2017
  • In the present study, a numerical model for probability analysis of optimal design of fatigue non-uniform crack growth behaviour of a cracked aluminium 2024 T3 plate repaired with a bonded composite patch is investigated. The proposed 3D numerical model has advanced in literatures, which gathers in a unique study: problems of reliability, optimization, fatigue, cracks and repair of plates subjected to tensile loadings. To achieve this aim, a finite element modelling is carried out to determine the evolution of the stress intensity factor at the crack tip Paris law is used to predict the fatigue life for a give n crack. To have an optimal volume of our patch satisfied the practical fatigue life, a procedure of optimization is proposed. Finally, the probabilistic analysis is performed in order to a show that optimized patch design is influenced by uncertainties related to mechanical and geometrical properties during the manufacturing process.

A study on Accelerated Life Prediction of Gas Welded joint of STS301L (1. Plug and Ring type) (STS301L 가스용접이음재의 가속수명에측에 관한 연구 (1. Plug and Ring type))

  • Baek, Seung-Yeb;Bae, Dong-Ho
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.1355-1360
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    • 2008
  • Stainless steel sheets are widely used as the structure material for the railroad cars and the commercial vehicles. These kinds structures used stainless steel sheets are commonly fabricated by using the gas welding. Gas welding is very important and useful technology in fabrication of an railroad car and vehicles structure. However fatigue strength of the gas welded joints is considerably lower than parent metal due to stress concentration at the weldment, fatigue strength evaluation of gas welded joints are very important to evaluate the reliability and durability of railroad cars and to establish a criterion of long life fatigue design. In this paper, ${\Delta}P-N_f$ curve were obtained by fatigue tests. Using these results, the accelerated life test (ALT) is conducted. From the experimental results, an acceleration model is derived and acceleration factors are estimated. So it is intended to obtain the useful information for the fatigue lifetime of plug and ring gas welded joints and data analysis by statistic reliability method, to save time and cost, and to develop optimum accelerated life prediction plans.

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