Experimental investigations were pedermed on the plastic deformation along bilinear strain paths with various values of corner-angle by subjecting thin-walled tubular specimens of type 302 stainless steel to combined ...Experimental investigations were pedermed on the plastic deformation along bilinear strain paths with various values of corner-angle by subjecting thin-walled tubular specimens of type 302 stainless steel to combined axial and torsional loads. Variations of scalar and vectorial behavior of the stress response are discnssed in the vector space of plastic strain. It is found that the intrinsic geometry of loading path, the plastic strain history and the coapled effect among strain components effect effectively the stress response of the material. The experimental results also show that these effects will disappear gradually with increasing strain.展开更多
The traditional one-dimensional ultrasonic beam steering has time delay and is thus a complicated problem. A numerical model of ultrasonic beam steering using Neumann boundary condition in multiplysics is presented in...The traditional one-dimensional ultrasonic beam steering has time delay and is thus a complicated problem. A numerical model of ultrasonic beam steering using Neumann boundary condition in multiplysics is presented in the present paper. This model is based on the discrete wave number method that has been proved theoretically to satisfy the continuous conditions. The propagating angle of novel model is a function of the distance instead of the time domain. The propagating wave fronts at desired angles are simulated with the single line sources for plane wave. The result indicates that any beam angle can be steered by discrete line elements resources without any time delay.展开更多
This study investigates the effects of a novel passive flow control mechanism,a flexible leading edge(LE),on the aerodynamic performance of a NACA 0018 airfoil and a scaled vertical axis wind turbine(VAWT)model.Wind t...This study investigates the effects of a novel passive flow control mechanism,a flexible leading edge(LE),on the aerodynamic performance of a NACA 0018 airfoil and a scaled vertical axis wind turbine(VAWT)model.Wind tunnel experiments were conducted on 2D airfoil sections under steady flow and dynamic pitching conditions,and a scaled VAWT model was tested in an open-field environment.The flexible LE airfoil demonstrated significant improvements in delaying static stall angles and enhancing lift generation during dynamic pitching by inducing earlier and prolonged high suction pressures.The scaled VAWT model with flexible LE blades showed increased rotational speeds and higher voltage outputs compared with the rigid blade VAWT,particularly at higher wind speeds.Both rotational speed and electrical voltage data suggest that the flexible LE structure enhances the aerodynamic efficiency of the VAWT.The findings suggest that the flexible LE structure is an efficient and cost-effective method to improve VAWT aerodynamic efficiency.展开更多
文摘Experimental investigations were pedermed on the plastic deformation along bilinear strain paths with various values of corner-angle by subjecting thin-walled tubular specimens of type 302 stainless steel to combined axial and torsional loads. Variations of scalar and vectorial behavior of the stress response are discnssed in the vector space of plastic strain. It is found that the intrinsic geometry of loading path, the plastic strain history and the coapled effect among strain components effect effectively the stress response of the material. The experimental results also show that these effects will disappear gradually with increasing strain.
基金supported by the National Natural Science Foundation of China (10972014)
文摘The traditional one-dimensional ultrasonic beam steering has time delay and is thus a complicated problem. A numerical model of ultrasonic beam steering using Neumann boundary condition in multiplysics is presented in the present paper. This model is based on the discrete wave number method that has been proved theoretically to satisfy the continuous conditions. The propagating angle of novel model is a function of the distance instead of the time domain. The propagating wave fronts at desired angles are simulated with the single line sources for plane wave. The result indicates that any beam angle can be steered by discrete line elements resources without any time delay.
文摘This study investigates the effects of a novel passive flow control mechanism,a flexible leading edge(LE),on the aerodynamic performance of a NACA 0018 airfoil and a scaled vertical axis wind turbine(VAWT)model.Wind tunnel experiments were conducted on 2D airfoil sections under steady flow and dynamic pitching conditions,and a scaled VAWT model was tested in an open-field environment.The flexible LE airfoil demonstrated significant improvements in delaying static stall angles and enhancing lift generation during dynamic pitching by inducing earlier and prolonged high suction pressures.The scaled VAWT model with flexible LE blades showed increased rotational speeds and higher voltage outputs compared with the rigid blade VAWT,particularly at higher wind speeds.Both rotational speed and electrical voltage data suggest that the flexible LE structure enhances the aerodynamic efficiency of the VAWT.The findings suggest that the flexible LE structure is an efficient and cost-effective method to improve VAWT aerodynamic efficiency.
