New pavement construction techniques and the increased use of recycled materials have led to unexpected and premature pavement failure in recent years.The pavement’s exposure to daily and seasonal extreme temperature...New pavement construction techniques and the increased use of recycled materials have led to unexpected and premature pavement failure in recent years.The pavement’s exposure to daily and seasonal extreme temperature and repeated vehicular loads accumulate damage.Pavement cracking occurs once the cumulative damage surpasses the material’s cracking threshold.Fatigue crack is the most common pavement cracking type.Over the past four decades,researchers have carried out numerous experiments and analyses to understand pavement cracking.This paper aims to provide an overview of fatigue cracking and discuss various fatigue test methods for characterizing asphalt concrete mixtures.The article also discusses the most common phenomenological and mechanistic models for predicting the fatigue life of asphalt concrete pavements based on different fatigue test results.The paper details the implementation of the commonly used numerical models found in numerical simulation software and their prediction ability for the fatigue life of a pavement structure.Two major flaws in current evaluation methods are the sensitivity of experimental results and the lack of reliability of some predictive models.Multiscale asphalt material characterization is the ongoing practice for determining the most appropriate performance evaluation tool.However,proceeding with future research objectives is unrealistic until the accuracy of the tests and reliability of the predictions can be verified against actual field results.This critical review of the fatigue life predictions of asphalt mixtures and pavements should help to refine or redefine the right course of action for future research.展开更多
通过实验研究了2种频率(110 Hz和20 k Hz)循环载荷作用下航空发动机叶片材料TC17合金的超高周疲劳失效行为,分析了不同失效形式下的裂纹萌生机理。结果表明,TC17合金在2种实验载荷频率下均存在表面和内部萌生裂纹诱发疲劳失效2种失效形...通过实验研究了2种频率(110 Hz和20 k Hz)循环载荷作用下航空发动机叶片材料TC17合金的超高周疲劳失效行为,分析了不同失效形式下的裂纹萌生机理。结果表明,TC17合金在2种实验载荷频率下均存在表面和内部萌生裂纹诱发疲劳失效2种失效形式,表面萌生裂纹诱发的疲劳失效主要是由加工缺陷和循环载荷作用下试样表面滑移处应力集中引起的横向裂纹所致,内部萌生裂纹诱发的疲劳失效是由循环载荷作用下材料初生α相的滑移断裂所致。失效机理的不同使得材料的应力-疲劳寿命(S-N)曲线呈双线性,载荷频率对TC17合金的裂纹萌生形式和萌生机理的影响不显著。建立了基于薄弱取向晶粒区域尺寸的疲劳强度预测模型,模型预测值与实验值吻合较好。展开更多
文摘New pavement construction techniques and the increased use of recycled materials have led to unexpected and premature pavement failure in recent years.The pavement’s exposure to daily and seasonal extreme temperature and repeated vehicular loads accumulate damage.Pavement cracking occurs once the cumulative damage surpasses the material’s cracking threshold.Fatigue crack is the most common pavement cracking type.Over the past four decades,researchers have carried out numerous experiments and analyses to understand pavement cracking.This paper aims to provide an overview of fatigue cracking and discuss various fatigue test methods for characterizing asphalt concrete mixtures.The article also discusses the most common phenomenological and mechanistic models for predicting the fatigue life of asphalt concrete pavements based on different fatigue test results.The paper details the implementation of the commonly used numerical models found in numerical simulation software and their prediction ability for the fatigue life of a pavement structure.Two major flaws in current evaluation methods are the sensitivity of experimental results and the lack of reliability of some predictive models.Multiscale asphalt material characterization is the ongoing practice for determining the most appropriate performance evaluation tool.However,proceeding with future research objectives is unrealistic until the accuracy of the tests and reliability of the predictions can be verified against actual field results.This critical review of the fatigue life predictions of asphalt mixtures and pavements should help to refine or redefine the right course of action for future research.
文摘通过实验研究了2种频率(110 Hz和20 k Hz)循环载荷作用下航空发动机叶片材料TC17合金的超高周疲劳失效行为,分析了不同失效形式下的裂纹萌生机理。结果表明,TC17合金在2种实验载荷频率下均存在表面和内部萌生裂纹诱发疲劳失效2种失效形式,表面萌生裂纹诱发的疲劳失效主要是由加工缺陷和循环载荷作用下试样表面滑移处应力集中引起的横向裂纹所致,内部萌生裂纹诱发的疲劳失效是由循环载荷作用下材料初生α相的滑移断裂所致。失效机理的不同使得材料的应力-疲劳寿命(S-N)曲线呈双线性,载荷频率对TC17合金的裂纹萌生形式和萌生机理的影响不显著。建立了基于薄弱取向晶粒区域尺寸的疲劳强度预测模型,模型预测值与实验值吻合较好。
