为研究中高应变率下NRP和掺高粘剂的SBS两种改性剂对AC-13型沥青混凝土动力性能的影响,采用直径74 mm SHPB装置进行了4个气压下的冲击压缩试验,获得了不同种类改性沥青混凝土的破坏形态及应力-应变曲线。研究表明:沥青混凝土动态应力-...为研究中高应变率下NRP和掺高粘剂的SBS两种改性剂对AC-13型沥青混凝土动力性能的影响,采用直径74 mm SHPB装置进行了4个气压下的冲击压缩试验,获得了不同种类改性沥青混凝土的破坏形态及应力-应变曲线。研究表明:沥青混凝土动态应力-应变曲线分为弹性变形、塑性强化和塑性破坏3个阶段,破坏形态分为裂缝、破损、块裂和碎裂4种;两种改性剂均能改善沥青混凝土的抗冲击性能,并且对峰值应力和冲击韧性的应变率敏感性有一定影响,在不同应变率范围内两种改性剂对冲击韧性增强作用不同,NRP对峰值应力增强作用优于掺高粘剂的SBS;应变率超过130/s时,沥青混凝土出现弹性模量退化现象,NRP对弹性模量有提高作用。展开更多
A study is performed about the water entry of a flat-bottom structure by use of the FE software MSC Dytran. The aim of the study is to find out the effect of the air cushion and structural mass on the impact peak pres...A study is performed about the water entry of a flat-bottom structure by use of the FE software MSC Dytran. The aim of the study is to find out the effect of the air cushion and structural mass on the impact peak pressure and the role of splash in the course of water entry. Some FE models are built up and some cases including the flat-bottom structure with different masses impacting water at some constant or initial velocities are calculated. The calculation shows that air plays an important role in the course of water entry of a flat-bottom structure and the compression of the air captured by the flat- bottom structure produces the first peak pressure. And the mass of the structure has a great effect on the peak value of impact pressure. The structure with different masses will produce different impact pressures even at the same impact velocity. Splash will occur a long time after the impact pressure reaches the peak value. A formula is given for the calculation of the peak value of impact pressure in this paper.展开更多
This paper presents the probability distribution of the slamming pressure from an experimental study of regular wave slamming on an elastically supported horizontal deck. The time series of the slamming pressure durin...This paper presents the probability distribution of the slamming pressure from an experimental study of regular wave slamming on an elastically supported horizontal deck. The time series of the slamming pressure during the wave impact were first obtained through statistical analyses on experimental data. The exceeding probability distribution of the maximum slamming pressure peak and distribution parameters were analyzed, and the results show that the exceeding probability distribution of the maximum slamming pressure peak accords with the three-parameter Weibull distribution. Furthermore, the range and relationships of the distribution parameters were studied. The sum of the location parameter D and the scale parameter L was approximately equal to 1.0, and the exceeding probability was more than 36.79% when the random peak was equal to the sample average during the wave impact. The variation of the distribution parameters and slamming pressure under different model conditions were comprehensively presented, and the parameter values of the Weibull distribution of wave-slamming pressure peaks were different due to different test models. The parameter values were found to decrease due to the increased stiffness of the elastic support. The damage criterion of the structure model caused by the wave impact was initially discussed, and the structure model was destroyed when the average slamming time was greater than a certain value during the duration of the wave impact. The conclusions of the experimental study were then described.展开更多
文摘为研究中高应变率下NRP和掺高粘剂的SBS两种改性剂对AC-13型沥青混凝土动力性能的影响,采用直径74 mm SHPB装置进行了4个气压下的冲击压缩试验,获得了不同种类改性沥青混凝土的破坏形态及应力-应变曲线。研究表明:沥青混凝土动态应力-应变曲线分为弹性变形、塑性强化和塑性破坏3个阶段,破坏形态分为裂缝、破损、块裂和碎裂4种;两种改性剂均能改善沥青混凝土的抗冲击性能,并且对峰值应力和冲击韧性的应变率敏感性有一定影响,在不同应变率范围内两种改性剂对冲击韧性增强作用不同,NRP对峰值应力增强作用优于掺高粘剂的SBS;应变率超过130/s时,沥青混凝土出现弹性模量退化现象,NRP对弹性模量有提高作用。
文摘A study is performed about the water entry of a flat-bottom structure by use of the FE software MSC Dytran. The aim of the study is to find out the effect of the air cushion and structural mass on the impact peak pressure and the role of splash in the course of water entry. Some FE models are built up and some cases including the flat-bottom structure with different masses impacting water at some constant or initial velocities are calculated. The calculation shows that air plays an important role in the course of water entry of a flat-bottom structure and the compression of the air captured by the flat- bottom structure produces the first peak pressure. And the mass of the structure has a great effect on the peak value of impact pressure. The structure with different masses will produce different impact pressures even at the same impact velocity. Splash will occur a long time after the impact pressure reaches the peak value. A formula is given for the calculation of the peak value of impact pressure in this paper.
基金support from the National Natural Science Foundation of China (Nos. 51579103 and 51709118)the China Postdoctoral Science Foundation (No. 2017M612669)+2 种基金the Fundamental Research Funds for the Central Universities (No. 2017BQ089)the Key Scientific Research Projects in Henan Province (No. 18B570005)the Open Research Foundation of Key Laboratory of the Pearl River Estuarine Dynamics and Associated Process Regulation, Ministry of Water Resources ([2017]KJ01)
文摘This paper presents the probability distribution of the slamming pressure from an experimental study of regular wave slamming on an elastically supported horizontal deck. The time series of the slamming pressure during the wave impact were first obtained through statistical analyses on experimental data. The exceeding probability distribution of the maximum slamming pressure peak and distribution parameters were analyzed, and the results show that the exceeding probability distribution of the maximum slamming pressure peak accords with the three-parameter Weibull distribution. Furthermore, the range and relationships of the distribution parameters were studied. The sum of the location parameter D and the scale parameter L was approximately equal to 1.0, and the exceeding probability was more than 36.79% when the random peak was equal to the sample average during the wave impact. The variation of the distribution parameters and slamming pressure under different model conditions were comprehensively presented, and the parameter values of the Weibull distribution of wave-slamming pressure peaks were different due to different test models. The parameter values were found to decrease due to the increased stiffness of the elastic support. The damage criterion of the structure model caused by the wave impact was initially discussed, and the structure model was destroyed when the average slamming time was greater than a certain value during the duration of the wave impact. The conclusions of the experimental study were then described.
