The physical properties and microstructure of SUF are investigated to develop a highly effective cement matrix crack-patching material for concrete cracks. The SEM and XRD determination of hardened SUF shows that the ...The physical properties and microstructure of SUF are investigated to develop a highly effective cement matrix crack-patching material for concrete cracks. The SEM and XRD determination of hardened SUF shows that the microstructure of SUF is dense and compact with a lot of C-S-H gels and ettringite. Also, the mechanism of shrinkage compensating is discussed.展开更多
Based on the finite element method, a numerical investigation into the bonded repair efficiency of cracked plates under in plane biaxial loadings is presented. The main considerations are: reduction in stress intensi...Based on the finite element method, a numerical investigation into the bonded repair efficiency of cracked plates under in plane biaxial loadings is presented. The main considerations are: reduction in stress intensity factor (SIF) at the crack tip, the maximum tensile stress in the composite patch and the maximum shear stress in the adhesive bond between the patch and the plate. Without the patch, a tensile or compressive stress parallel to the crack has no effect on the SIF at the crack tip. While with a composite patch, there exists coupling effect between the normal stress parallel to the crack and the SIF, and the coupling effect depends significantly on ply orientation of the patch and the biaxial stress ratio of the plate.展开更多
The conventional case of patch repair involves bonding a patch over single damage/hole in the laminate.This work investigates the effect of interaction of two holes on the tensile behavior patch repaired carbon epoxy ...The conventional case of patch repair involves bonding a patch over single damage/hole in the laminate.This work investigates the effect of interaction of two holes on the tensile behavior patch repaired carbon epoxy woven laminates.The specimens of[0°/45°/45°/0°]laminates were repaired with adhesively bonded two-ply[45°]2external patches.Three different cases of drilled specimens were produced with different hole arrangements viz.specimens with single central hole(SH),with two holes aligned along the longitudinal axis(LH)and with two holes along transverse axis(TH).The two-hole specimens were repaired with two different types,i.e.single large patches(SP)and with the two smaller patches(DP)of combined bonding area equal to the single large patches.Digital image correlation(DIC)was employed to capture strain contours.The results reveal the difference in the load transfer through the patches depending upon the arrangement of holes.The TH repaired specimen exhibit significant load recovery(SP-32.75%,DP-34.62%)while the LH specimens result in very marginal(SP-6.11%,DP-4.10%)recovery compared to their drilled case.The TH specimen failed by crack growing through both the holes beneath the patch,while the LH specimens failed by the failure through only one hole.The use of single large patch over multiple holes and multiple small patches individually over each hole has no significant influence on load recovery.展开更多
在高速列车长期、快速行驶中,其转向架金属结构会因疲劳、应力、环境等因素影响,产生金属裂纹。为了在高速列车中的转型架金属表面实现远距离无损检测并判断是否存在裂纹,设计了一种应用在超高频频段的微带贴片型射频识别(Radio Frequen...在高速列车长期、快速行驶中,其转向架金属结构会因疲劳、应力、环境等因素影响,产生金属裂纹。为了在高速列车中的转型架金属表面实现远距离无损检测并判断是否存在裂纹,设计了一种应用在超高频频段的微带贴片型射频识别(Radio Frequency Identification,RFID)抗金属标签,配合RFID芯片,标定RFID阅读器与标签天线的位置和其发射天线的功率,当金属表面存在裂纹时标签天线谐振频率会向低频移动,并产生影响导致RFID系统识别距离的改变,从而实现金属表面裂纹检测。使用高频结构仿真(High Frequency Structure Simulator,HFSS)软件对天线结构进行优化,使其与芯片阻抗匹配,模拟了天线在金属表面存在裂纹的情况。由仿真结果可以分析得出:设计的无线有芯片微带贴片型RFID转向架表面裂纹检测标签能够有效地实现远距离监测金属表面裂纹长度、方向的变化情况。展开更多
在大地形三维多分辨率显示中,针对裂缝消除问题提出了一种基于LOD(Level of Detail)控制和裂缝可视性的改进算法。证明在四叉树网格可视距离/尺寸比>3时,必然满足限制四叉树约束;基于裂缝的可见性,在预处理阶段通过区分地形上升裂缝...在大地形三维多分辨率显示中,针对裂缝消除问题提出了一种基于LOD(Level of Detail)控制和裂缝可视性的改进算法。证明在四叉树网格可视距离/尺寸比>3时,必然满足限制四叉树约束;基于裂缝的可见性,在预处理阶段通过区分地形上升裂缝和地形下降裂缝,为后者添加与裂缝大小一致的几何图形来生成裂缝消除补丁;在实时渲染过程中,既不需要通过CPU计算来控制网格的层次差,也不需要通过CPU来识别相邻网格层次差和消除裂缝。实验测试表明:该算法简单有效,附加网格数据比裙边算法减少约75%,且完全能够避免地形裂缝的显示。展开更多
基金Funded by Railway Ministry Scientific Research Item
文摘The physical properties and microstructure of SUF are investigated to develop a highly effective cement matrix crack-patching material for concrete cracks. The SEM and XRD determination of hardened SUF shows that the microstructure of SUF is dense and compact with a lot of C-S-H gels and ettringite. Also, the mechanism of shrinkage compensating is discussed.
文摘Based on the finite element method, a numerical investigation into the bonded repair efficiency of cracked plates under in plane biaxial loadings is presented. The main considerations are: reduction in stress intensity factor (SIF) at the crack tip, the maximum tensile stress in the composite patch and the maximum shear stress in the adhesive bond between the patch and the plate. Without the patch, a tensile or compressive stress parallel to the crack has no effect on the SIF at the crack tip. While with a composite patch, there exists coupling effect between the normal stress parallel to the crack and the SIF, and the coupling effect depends significantly on ply orientation of the patch and the biaxial stress ratio of the plate.
基金the financial support by the Council of Scientific&Industrial Research (CSIR)-Research Scheme (22/0809/2019-EMR-Ⅱ)
文摘The conventional case of patch repair involves bonding a patch over single damage/hole in the laminate.This work investigates the effect of interaction of two holes on the tensile behavior patch repaired carbon epoxy woven laminates.The specimens of[0°/45°/45°/0°]laminates were repaired with adhesively bonded two-ply[45°]2external patches.Three different cases of drilled specimens were produced with different hole arrangements viz.specimens with single central hole(SH),with two holes aligned along the longitudinal axis(LH)and with two holes along transverse axis(TH).The two-hole specimens were repaired with two different types,i.e.single large patches(SP)and with the two smaller patches(DP)of combined bonding area equal to the single large patches.Digital image correlation(DIC)was employed to capture strain contours.The results reveal the difference in the load transfer through the patches depending upon the arrangement of holes.The TH repaired specimen exhibit significant load recovery(SP-32.75%,DP-34.62%)while the LH specimens result in very marginal(SP-6.11%,DP-4.10%)recovery compared to their drilled case.The TH specimen failed by crack growing through both the holes beneath the patch,while the LH specimens failed by the failure through only one hole.The use of single large patch over multiple holes and multiple small patches individually over each hole has no significant influence on load recovery.
文摘在高速列车长期、快速行驶中,其转向架金属结构会因疲劳、应力、环境等因素影响,产生金属裂纹。为了在高速列车中的转型架金属表面实现远距离无损检测并判断是否存在裂纹,设计了一种应用在超高频频段的微带贴片型射频识别(Radio Frequency Identification,RFID)抗金属标签,配合RFID芯片,标定RFID阅读器与标签天线的位置和其发射天线的功率,当金属表面存在裂纹时标签天线谐振频率会向低频移动,并产生影响导致RFID系统识别距离的改变,从而实现金属表面裂纹检测。使用高频结构仿真(High Frequency Structure Simulator,HFSS)软件对天线结构进行优化,使其与芯片阻抗匹配,模拟了天线在金属表面存在裂纹的情况。由仿真结果可以分析得出:设计的无线有芯片微带贴片型RFID转向架表面裂纹检测标签能够有效地实现远距离监测金属表面裂纹长度、方向的变化情况。
文摘在大地形三维多分辨率显示中,针对裂缝消除问题提出了一种基于LOD(Level of Detail)控制和裂缝可视性的改进算法。证明在四叉树网格可视距离/尺寸比>3时,必然满足限制四叉树约束;基于裂缝的可见性,在预处理阶段通过区分地形上升裂缝和地形下降裂缝,为后者添加与裂缝大小一致的几何图形来生成裂缝消除补丁;在实时渲染过程中,既不需要通过CPU计算来控制网格的层次差,也不需要通过CPU来识别相邻网格层次差和消除裂缝。实验测试表明:该算法简单有效,附加网格数据比裙边算法减少约75%,且完全能够避免地形裂缝的显示。
