对混凝土裂缝进行监测,有利于开展结构损伤评估工作。以某装配式地铁车站的地下连续墙-腰梁-支撑节点试验为背景,开展基于光学频域反射计(optical frequency domain reflectometer,OFDR)的分布式光纤技术在混凝土裂缝监测和识别中的应用...对混凝土裂缝进行监测,有利于开展结构损伤评估工作。以某装配式地铁车站的地下连续墙-腰梁-支撑节点试验为背景,开展基于光学频域反射计(optical frequency domain reflectometer,OFDR)的分布式光纤技术在混凝土裂缝监测和识别中的应用,研究不同加载条件下分布式光纤应变曲线的特征。试验表明:与单调加载相比,低周循环加载时得到的光纤应变曲线尖峰更多,峰值更小,表明低周循环加载造成的裂缝更多,但宽度更小,这与现场观察到的现象一致;单调加载中的光纤应变曲线更易于裂缝的识别和精准定位。展开更多
Printed circuit heat exchangers(PCHEs)are considered as the most promising heat exchangers for use of the supercritical carbon dioxide(S-CO_(2))Brayton cycle.As crucial components operating at high pressure and therma...Printed circuit heat exchangers(PCHEs)are considered as the most promising heat exchangers for use of the supercritical carbon dioxide(S-CO_(2))Brayton cycle.As crucial components operating at high pressure and thermal load at the same time,PCHE structural integrity evaluations are essential.In this study,to assess the structural strength of PCHEs serving as recuperators and precoolers in the S-CO_(2) Brayton cycle as a waste heat recovery system for marine engines,the finite element method(FEM)is used and compared with a currently used method from ASME codes.The effects of temperature and pressure on the hot and cold sides are studied in terms of the temperature and pressure differences between the two sides and the main factors affecting its strength discussed.Then,detailed stress intensities of a PCHE under design conditions are investigated,and the results indicate that the highest stress appears at the middle of the semicircular arc of the channel,except for a concentration near the channel tip regions.Stresses of the PCHE are mainly caused by both pressure and temperature differences,with the minimum effect from temperature.The synthesis of the temperature and pressure fields exhibits a complicated action on the total stress under the design conditions.FEM was a more comprehensive means for structural assessment than the method from ASME codes.Further structural optimization of PCHE is conducted to ensure a maximum life span.This research work can provide theoretical guidance for structural integrity assessment of PCHE for the S-CO_(2) Brayton cycle.展开更多
文摘对混凝土裂缝进行监测,有利于开展结构损伤评估工作。以某装配式地铁车站的地下连续墙-腰梁-支撑节点试验为背景,开展基于光学频域反射计(optical frequency domain reflectometer,OFDR)的分布式光纤技术在混凝土裂缝监测和识别中的应用,研究不同加载条件下分布式光纤应变曲线的特征。试验表明:与单调加载相比,低周循环加载时得到的光纤应变曲线尖峰更多,峰值更小,表明低周循环加载造成的裂缝更多,但宽度更小,这与现场观察到的现象一致;单调加载中的光纤应变曲线更易于裂缝的识别和精准定位。
基金financially supported by the High-Tech Ship Research Project of Ministry of Industry and Information Technology(No.MIIT[2017]614)the Fundamental Research Funds for the Central Universities(WUT:2021IUA105)。
文摘Printed circuit heat exchangers(PCHEs)are considered as the most promising heat exchangers for use of the supercritical carbon dioxide(S-CO_(2))Brayton cycle.As crucial components operating at high pressure and thermal load at the same time,PCHE structural integrity evaluations are essential.In this study,to assess the structural strength of PCHEs serving as recuperators and precoolers in the S-CO_(2) Brayton cycle as a waste heat recovery system for marine engines,the finite element method(FEM)is used and compared with a currently used method from ASME codes.The effects of temperature and pressure on the hot and cold sides are studied in terms of the temperature and pressure differences between the two sides and the main factors affecting its strength discussed.Then,detailed stress intensities of a PCHE under design conditions are investigated,and the results indicate that the highest stress appears at the middle of the semicircular arc of the channel,except for a concentration near the channel tip regions.Stresses of the PCHE are mainly caused by both pressure and temperature differences,with the minimum effect from temperature.The synthesis of the temperature and pressure fields exhibits a complicated action on the total stress under the design conditions.FEM was a more comprehensive means for structural assessment than the method from ASME codes.Further structural optimization of PCHE is conducted to ensure a maximum life span.This research work can provide theoretical guidance for structural integrity assessment of PCHE for the S-CO_(2) Brayton cycle.
