板结构的稳定性在船舶设计和强度校核中占据重要地位。为研究船体薄板的剪切稳定性,本文设计画框式夹具对方形薄板进行面内剪切屈曲试验,试验中采用三维数字图像相关法(3 Dimensions Digital Image Correlation,简称3D-DIC),获得了载荷...板结构的稳定性在船舶设计和强度校核中占据重要地位。为研究船体薄板的剪切稳定性,本文设计画框式夹具对方形薄板进行面内剪切屈曲试验,试验中采用三维数字图像相关法(3 Dimensions Digital Image Correlation,简称3D-DIC),获得了载荷-端部伸长率曲线、全场位移/应变等力学响应信息。载荷-端部伸长率关系揭示了薄板在面内剪切工况下的承载特性,确定了屈曲失稳临界载荷;通过分析薄板在典型时刻的位移场、应变场信息,发现薄板的法向变形会随面内剪切载荷增加而增大。薄板失稳后,沿垂直对角线存在对称分布的三个半波,内部波幅大于外部波幅,应变波形和云图在后屈曲过程中会趋于稳定。通过分析薄板关键点的法向位移和米塞斯应变随时间的响应曲线,提出并验证了一种识别面内受剪薄板屈曲失稳的新方法。本文为船用薄板面内剪切稳定性的试验研究和力学行为分析等提供了有益参考。展开更多
Cracking affected by wetting-drying cycles is a major cause of shallow failure of soft rock slopes.Knowledge of rock tensile properties and cracking behaviors helps better assess the stability of soft rock slopes.This...Cracking affected by wetting-drying cycles is a major cause of shallow failure of soft rock slopes.Knowledge of rock tensile properties and cracking behaviors helps better assess the stability of soft rock slopes.This study aims to examine the cracking behaviors and tensile strength of silty mudstone under wetting-drying cycles.The wetting-drying cycle and Brazilian splitting tests were performed on silty mudstone considering various cycle number and amplitude.The cracking behaviors of wetting-drying cycles were analyzed by digital image correlation,three-dimensional(3D)scanning technology,and scanning electron microscopy.The results reveal a spiral-like pattern of crack ratio escalation in silty mudstone,with a higher crack ratio observed during drying than wetting.Tensile strength and fracture energy correlate negatively with cycle number or amplitude,with cycle number exerting a more pronounced effect.The variance of the maximum principal strain reflects stages of initial deformation,linear deformation,strain localization,and stable deformation.The formation of strain localization zones reveals the physical process of crack propagation.Crack tip opening displacement progresses through stages of slow growth,exponential growth,and linear growth,delineating the process from crack initiation to stable extension.Failure modes of silty mudstone primarily involve tensile and tensile-shear failure,influenced by the geometric parameters of cracks induced by wetting-drying cycles.Fracture surface roughness and fractal dimension increase with cycle number due to mineral dissolution,physical erosion,and nondirectional crack propagation.Hydration-swelling and dehydration-shrinkage of clay minerals,along with absorption-drying cracking,initiate and merge cracks,leading to degradation of the rock mechanical properties.The findings could provide insights for mitigating shallow cracking of soft rock slopes under wetting-drying cycles.展开更多
文摘板结构的稳定性在船舶设计和强度校核中占据重要地位。为研究船体薄板的剪切稳定性,本文设计画框式夹具对方形薄板进行面内剪切屈曲试验,试验中采用三维数字图像相关法(3 Dimensions Digital Image Correlation,简称3D-DIC),获得了载荷-端部伸长率曲线、全场位移/应变等力学响应信息。载荷-端部伸长率关系揭示了薄板在面内剪切工况下的承载特性,确定了屈曲失稳临界载荷;通过分析薄板在典型时刻的位移场、应变场信息,发现薄板的法向变形会随面内剪切载荷增加而增大。薄板失稳后,沿垂直对角线存在对称分布的三个半波,内部波幅大于外部波幅,应变波形和云图在后屈曲过程中会趋于稳定。通过分析薄板关键点的法向位移和米塞斯应变随时间的响应曲线,提出并验证了一种识别面内受剪薄板屈曲失稳的新方法。本文为船用薄板面内剪切稳定性的试验研究和力学行为分析等提供了有益参考。
基金the financial support by the National Natural Science Foundation of China(Grant No.52108397)“Xiaohe”Science and Technology Talent Special Project(Grant No.2024 TJ-X06)Water Resources Science and Technology Project of Hunan Province(Grant No.XSKJ2023059-41).
文摘Cracking affected by wetting-drying cycles is a major cause of shallow failure of soft rock slopes.Knowledge of rock tensile properties and cracking behaviors helps better assess the stability of soft rock slopes.This study aims to examine the cracking behaviors and tensile strength of silty mudstone under wetting-drying cycles.The wetting-drying cycle and Brazilian splitting tests were performed on silty mudstone considering various cycle number and amplitude.The cracking behaviors of wetting-drying cycles were analyzed by digital image correlation,three-dimensional(3D)scanning technology,and scanning electron microscopy.The results reveal a spiral-like pattern of crack ratio escalation in silty mudstone,with a higher crack ratio observed during drying than wetting.Tensile strength and fracture energy correlate negatively with cycle number or amplitude,with cycle number exerting a more pronounced effect.The variance of the maximum principal strain reflects stages of initial deformation,linear deformation,strain localization,and stable deformation.The formation of strain localization zones reveals the physical process of crack propagation.Crack tip opening displacement progresses through stages of slow growth,exponential growth,and linear growth,delineating the process from crack initiation to stable extension.Failure modes of silty mudstone primarily involve tensile and tensile-shear failure,influenced by the geometric parameters of cracks induced by wetting-drying cycles.Fracture surface roughness and fractal dimension increase with cycle number due to mineral dissolution,physical erosion,and nondirectional crack propagation.Hydration-swelling and dehydration-shrinkage of clay minerals,along with absorption-drying cracking,initiate and merge cracks,leading to degradation of the rock mechanical properties.The findings could provide insights for mitigating shallow cracking of soft rock slopes under wetting-drying cycles.
