In tube hydroforming with axial feeding,under the effect of coupled internal pressure and axial stress,wrinkles often occur and affect the forming results.Wrinkling behavior of an AZ31B magnesium alloy tube was experi...In tube hydroforming with axial feeding,under the effect of coupled internal pressure and axial stress,wrinkles often occur and affect the forming results.Wrinkling behavior of an AZ31B magnesium alloy tube was experimentally investigated with different loading paths at different temperatures.Features of wrinkles,including shape,radius and width,were acquired from the experiments,as well as the thickness distribution.Numerical simulations were carried out to reveal the stress state during warm hydroforming,and then the strain history of material at the top and bottom of the wrinkles were analyzed according to the stress tracks and yielding ellipse.Finally,effects of loading paths on expansion ratio limit of warm hydroforming were analyzed.It is verified that at a certain temperature,expansion ratio limit can be increased obviously by applying a proper loading path and realizing enough axial feeding.展开更多
Hydroforming of magnesium and aluminum alloy tube at elevated temperature is becoming a very promising method to manufacture light-weight hollow components.Uniaxial tensile test and hydrobulging test were used to inve...Hydroforming of magnesium and aluminum alloy tube at elevated temperature is becoming a very promising method to manufacture light-weight hollow components.Uniaxial tensile test and hydrobulging test were used to investigate the formability of AZ31B magnesium tube at different temperatures.The tube was manufactured by porthole die extrusion.Results show that as temperature increase,the tension formability along the extrusion direction measured by tensile test increases significantly,whereas the maximum hydrobulging ratio measured by hydrobulging test does not change accordingly.This anisotropy character of the tube,i.e.,different properties in axial direction and hoop direction,is mainly dependant on the extrusion process.In addition,there exists several weld lines along the extrusion direction.These weld lines will become the weakest positions when formed at elevated temperature,and will consequently decrease the formability of the tube during hydroforming process.展开更多
基金Project(NCET-07-0237)supported by the Program for New Century Excellent Talents in University,China
文摘In tube hydroforming with axial feeding,under the effect of coupled internal pressure and axial stress,wrinkles often occur and affect the forming results.Wrinkling behavior of an AZ31B magnesium alloy tube was experimentally investigated with different loading paths at different temperatures.Features of wrinkles,including shape,radius and width,were acquired from the experiments,as well as the thickness distribution.Numerical simulations were carried out to reveal the stress state during warm hydroforming,and then the strain history of material at the top and bottom of the wrinkles were analyzed according to the stress tracks and yielding ellipse.Finally,effects of loading paths on expansion ratio limit of warm hydroforming were analyzed.It is verified that at a certain temperature,expansion ratio limit can be increased obviously by applying a proper loading path and realizing enough axial feeding.
基金This work is financially supported by the National Natural Science Fund for Distinguished Young Scholars(No50525516)the Specialized Research Fund for the Doctoral Program of Higher Edu-cation (No20050213041)
文摘Hydroforming of magnesium and aluminum alloy tube at elevated temperature is becoming a very promising method to manufacture light-weight hollow components.Uniaxial tensile test and hydrobulging test were used to investigate the formability of AZ31B magnesium tube at different temperatures.The tube was manufactured by porthole die extrusion.Results show that as temperature increase,the tension formability along the extrusion direction measured by tensile test increases significantly,whereas the maximum hydrobulging ratio measured by hydrobulging test does not change accordingly.This anisotropy character of the tube,i.e.,different properties in axial direction and hoop direction,is mainly dependant on the extrusion process.In addition,there exists several weld lines along the extrusion direction.These weld lines will become the weakest positions when formed at elevated temperature,and will consequently decrease the formability of the tube during hydroforming process.
