In this study, experiments were carried out to investigate aerodynamic characteristics of a high-speed train on viaducts in turbulent crosswinds using a 1:25 scaled sectional model wind-tunnel testing. Pressure measur...In this study, experiments were carried out to investigate aerodynamic characteristics of a high-speed train on viaducts in turbulent crosswinds using a 1:25 scaled sectional model wind-tunnel testing. Pressure measurements of two typical sections, one train-head section and one train-body section, at the windward and leeward tracks were conducted under the smooth and turbulence flows with wind attack angles between-6° and 6°, and the corresponding aerodynamic force coefficients were also calculated using the integral method. The experimental results indicate that the track position affects the mean aerodynamic characteristics of the vehicle, especially for the train-body section. The fluctuating pressure coefficients at the leeward track are more significantly affected by the bridge interference compared to those at the windward track. The effect of turbulence on the train-head section is less than that on the train-body section. Additionally, the mean aerodynamic force coefficients are almost negatively correlated to wind attack angles, which is more prominent for vehicles at the leeward track. Moreover, the lateral force plays a critical role in determining the corresponding overturning moment, especially on the train-body section.展开更多
Based on experiment modal analysis(EMA) and operation modal analysis(OMA), the dynamic characteristics of cylindrical grinding machine were measured and provided a basis for further failure analysis.The influences of ...Based on experiment modal analysis(EMA) and operation modal analysis(OMA), the dynamic characteristics of cylindrical grinding machine were measured and provided a basis for further failure analysis.The influences of grinding parameters on dynamic characteristics were studied by analyzing the diagnostic signals extracted from racing and grinding experiments.The significant frequency of 38 Hz related to grinding wheel spindle speed of 2 307 r/min showed that the wheel spindle system was in a state of imbalan...展开更多
Geobelt deformation is of significance when making prejudgments on potential failure planes in reinforced structures.A failure plane results from two geobelt failure modes,tensile failure and pullout.In order to inves...Geobelt deformation is of significance when making prejudgments on potential failure planes in reinforced structures.A failure plane results from two geobelt failure modes,tensile failure and pullout.In order to investigate the deformation characteristics of geobelts in two failure modes,results from pullout tests on sensor-enabled geobelts(SEGBs)with various lengths in sand are reported here across a range of normal pressures.Self-measurements of SEGB can provide data during the tests regarding distributions of strain,stress,and displacement.Data collected during pullout tests reveal the effects of normal pressures and specimen lengths on failure mode.A critical line considering normal pressure and specimen length is derived to describe the transition between two failure modes,an approach which can be utilized for preliminary predictions of failure mode in pullout tests.Warning criteria established based on critical line and data from the self-measurements of SEGB are proposed for failure mode prediction which can contribute to prejudgments of potential failure plane in geosynthetically reinforced soil structures.展开更多
基金Projects(51808563,51925808)supported by the National Natural Science Foundation of ChinaProject(KLWRTBMC18-03)supported by the Open Research Fund of the Key Laboratory of Wind Resistance Technology of Bridges of ChinaProject(2017YFB1201204)supported by the National Key R&D Program of China。
文摘In this study, experiments were carried out to investigate aerodynamic characteristics of a high-speed train on viaducts in turbulent crosswinds using a 1:25 scaled sectional model wind-tunnel testing. Pressure measurements of two typical sections, one train-head section and one train-body section, at the windward and leeward tracks were conducted under the smooth and turbulence flows with wind attack angles between-6° and 6°, and the corresponding aerodynamic force coefficients were also calculated using the integral method. The experimental results indicate that the track position affects the mean aerodynamic characteristics of the vehicle, especially for the train-body section. The fluctuating pressure coefficients at the leeward track are more significantly affected by the bridge interference compared to those at the windward track. The effect of turbulence on the train-head section is less than that on the train-body section. Additionally, the mean aerodynamic force coefficients are almost negatively correlated to wind attack angles, which is more prominent for vehicles at the leeward track. Moreover, the lateral force plays a critical role in determining the corresponding overturning moment, especially on the train-body section.
文摘Based on experiment modal analysis(EMA) and operation modal analysis(OMA), the dynamic characteristics of cylindrical grinding machine were measured and provided a basis for further failure analysis.The influences of grinding parameters on dynamic characteristics were studied by analyzing the diagnostic signals extracted from racing and grinding experiments.The significant frequency of 38 Hz related to grinding wheel spindle speed of 2 307 r/min showed that the wheel spindle system was in a state of imbalan...
基金Project supported by the National Key Research and Development Program of China(No.2018YFB1600100)the National Natural Science Foundation of China(Nos.51778346 , 51608461)。
文摘Geobelt deformation is of significance when making prejudgments on potential failure planes in reinforced structures.A failure plane results from two geobelt failure modes,tensile failure and pullout.In order to investigate the deformation characteristics of geobelts in two failure modes,results from pullout tests on sensor-enabled geobelts(SEGBs)with various lengths in sand are reported here across a range of normal pressures.Self-measurements of SEGB can provide data during the tests regarding distributions of strain,stress,and displacement.Data collected during pullout tests reveal the effects of normal pressures and specimen lengths on failure mode.A critical line considering normal pressure and specimen length is derived to describe the transition between two failure modes,an approach which can be utilized for preliminary predictions of failure mode in pullout tests.Warning criteria established based on critical line and data from the self-measurements of SEGB are proposed for failure mode prediction which can contribute to prejudgments of potential failure plane in geosynthetically reinforced soil structures.
