The Experts below are selected from a list of 33 Experts worldwide ranked by ideXlab platform
Shi Jian Yuan - One of the best experts on this subject based on the ideXlab platform.
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Effect of internal pressure on Corner Radius and thickness distribution of shear hydro-bending of 5A02 aluminum alloy tube
Transactions of Nonferrous Metals Society of China, 2012Co-Authors: Yong Wang, Shi Jian YuanAbstract:The effects of internal pressure on forming defects, Corner Radius and thickness distribution of 5A02 aluminum alloy shear hydro-bending tubes were studied by experiment. Numerical simulation was conducted to analyze the effect of internal pressure on axial strain and invariable lines of thickness strain. The ultra-small bending tubes were successfully manufactured when the relative internal pressure, ratio of internal pressure and yield stress of the material, is higher than 0.2. The relative bending Radius of the first outer Corner decreases from 0.3 to 0.025 when the relative internal pressure increases from 0.2 to 1.2. The axial thickness distribution is different in intrados and extrados. The changing rate of thickness is larger with a higher internal pressure. The minimum thickness decreases from 1.45 mm to 0.87 mm when the relative internal pressure changes from 0.2 to 1.2. The tube is divided into feeding zone, the first Corner, shearing zone, the second Corner and holding zone. The strain of feeding zone and the first Corner is compressive caused by the feeding. The strain of the second Corner and holding zone is tensile for far away from feeding punches. The strain of shearing zone changes from compressive to tensile with rising of internal pressure. On one hand, the Smaller Corner Radius formed by higher internal pressure blocks the feeding. On the other hand, the Corner filling strengthens the extensive strain of shearing zone. In the feeding zone and holding zone, thickness strain is positive, and the tube thickens. In the Corner and shear zones, thickness strain is negative, and the tube thins.
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Effect of internal pressure on Corner Radius and thickness distribution of shear hydro-bending of 5A02 aluminum alloy tube
Transactions of Nonferrous Metals Society of China (English Edition), 2012Co-Authors: Yong Wang, Cong Han, Shi Jian YuanAbstract:The effects of internal pressure on forming defects, Corner Radius and thickness distribution of 5A02 aluminum alloy shear hydro-bending tubes were studied by experiment. Numerical simulation was conducted to analyze the effect of internal pressure on axial strain and invariable lines of thickness strain. The ultra-small bending tubes were successfully manufactured when the relative internal pressure, ratio of internal pressure and yield stress of the material, is higher than 0.2. The relative bending Radius of the first outer Corner decreases from 0.3 to 0.025 when the relative internal pressure increases from 0.2 to 1.2. The axial thickness distribution is different in intrados and extrados. The changing rate of thickness is larger with a higher internal pressure. The minimum thickness decreases from 1.45 mm to 0.87 mm when the relative internal pressure changes from 0.2 to 1.2. The tube is divided into feeding zone, the first Corner, shearing zone, the second Corner and holding zone. The strain of feeding zone and the first Corner is compressive caused by the feeding. The strain of the second Corner and holding zone is tensile for far away from feeding punches. The strain of shearing zone changes from compressive to tensile with rising of internal pressure. On one hand, the Smaller Corner Radius formed by higher internal pressure blocks the feeding. On the other hand, the Corner filling strengthens the extensive strain of shearing zone. In the feeding zone and holding zone, thickness strain is positive, and the tube thickens. In the Corner and shear zones, thickness strain is negative, and the tube thins. ?? 2012 The Nonferrous Metals Society of China.
Yong Wang - One of the best experts on this subject based on the ideXlab platform.
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Effect of internal pressure on Corner Radius and thickness distribution of shear hydro-bending of 5A02 aluminum alloy tube
Transactions of Nonferrous Metals Society of China, 2012Co-Authors: Yong Wang, Shi Jian YuanAbstract:The effects of internal pressure on forming defects, Corner Radius and thickness distribution of 5A02 aluminum alloy shear hydro-bending tubes were studied by experiment. Numerical simulation was conducted to analyze the effect of internal pressure on axial strain and invariable lines of thickness strain. The ultra-small bending tubes were successfully manufactured when the relative internal pressure, ratio of internal pressure and yield stress of the material, is higher than 0.2. The relative bending Radius of the first outer Corner decreases from 0.3 to 0.025 when the relative internal pressure increases from 0.2 to 1.2. The axial thickness distribution is different in intrados and extrados. The changing rate of thickness is larger with a higher internal pressure. The minimum thickness decreases from 1.45 mm to 0.87 mm when the relative internal pressure changes from 0.2 to 1.2. The tube is divided into feeding zone, the first Corner, shearing zone, the second Corner and holding zone. The strain of feeding zone and the first Corner is compressive caused by the feeding. The strain of the second Corner and holding zone is tensile for far away from feeding punches. The strain of shearing zone changes from compressive to tensile with rising of internal pressure. On one hand, the Smaller Corner Radius formed by higher internal pressure blocks the feeding. On the other hand, the Corner filling strengthens the extensive strain of shearing zone. In the feeding zone and holding zone, thickness strain is positive, and the tube thickens. In the Corner and shear zones, thickness strain is negative, and the tube thins.
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Effect of internal pressure on Corner Radius and thickness distribution of shear hydro-bending of 5A02 aluminum alloy tube
Transactions of Nonferrous Metals Society of China (English Edition), 2012Co-Authors: Yong Wang, Cong Han, Shi Jian YuanAbstract:The effects of internal pressure on forming defects, Corner Radius and thickness distribution of 5A02 aluminum alloy shear hydro-bending tubes were studied by experiment. Numerical simulation was conducted to analyze the effect of internal pressure on axial strain and invariable lines of thickness strain. The ultra-small bending tubes were successfully manufactured when the relative internal pressure, ratio of internal pressure and yield stress of the material, is higher than 0.2. The relative bending Radius of the first outer Corner decreases from 0.3 to 0.025 when the relative internal pressure increases from 0.2 to 1.2. The axial thickness distribution is different in intrados and extrados. The changing rate of thickness is larger with a higher internal pressure. The minimum thickness decreases from 1.45 mm to 0.87 mm when the relative internal pressure changes from 0.2 to 1.2. The tube is divided into feeding zone, the first Corner, shearing zone, the second Corner and holding zone. The strain of feeding zone and the first Corner is compressive caused by the feeding. The strain of the second Corner and holding zone is tensile for far away from feeding punches. The strain of shearing zone changes from compressive to tensile with rising of internal pressure. On one hand, the Smaller Corner Radius formed by higher internal pressure blocks the feeding. On the other hand, the Corner filling strengthens the extensive strain of shearing zone. In the feeding zone and holding zone, thickness strain is positive, and the tube thickens. In the Corner and shear zones, thickness strain is negative, and the tube thins. ?? 2012 The Nonferrous Metals Society of China.
Cong Han - One of the best experts on this subject based on the ideXlab platform.
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Effect of internal pressure on Corner Radius and thickness distribution of shear hydro-bending of 5A02 aluminum alloy tube
Transactions of Nonferrous Metals Society of China (English Edition), 2012Co-Authors: Yong Wang, Cong Han, Shi Jian YuanAbstract:The effects of internal pressure on forming defects, Corner Radius and thickness distribution of 5A02 aluminum alloy shear hydro-bending tubes were studied by experiment. Numerical simulation was conducted to analyze the effect of internal pressure on axial strain and invariable lines of thickness strain. The ultra-small bending tubes were successfully manufactured when the relative internal pressure, ratio of internal pressure and yield stress of the material, is higher than 0.2. The relative bending Radius of the first outer Corner decreases from 0.3 to 0.025 when the relative internal pressure increases from 0.2 to 1.2. The axial thickness distribution is different in intrados and extrados. The changing rate of thickness is larger with a higher internal pressure. The minimum thickness decreases from 1.45 mm to 0.87 mm when the relative internal pressure changes from 0.2 to 1.2. The tube is divided into feeding zone, the first Corner, shearing zone, the second Corner and holding zone. The strain of feeding zone and the first Corner is compressive caused by the feeding. The strain of the second Corner and holding zone is tensile for far away from feeding punches. The strain of shearing zone changes from compressive to tensile with rising of internal pressure. On one hand, the Smaller Corner Radius formed by higher internal pressure blocks the feeding. On the other hand, the Corner filling strengthens the extensive strain of shearing zone. In the feeding zone and holding zone, thickness strain is positive, and the tube thickens. In the Corner and shear zones, thickness strain is negative, and the tube thins. ?? 2012 The Nonferrous Metals Society of China.
Cristina J Bunget - One of the best experts on this subject based on the ideXlab platform.
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Mechanics of ultrasonic tube hydroforming
ProQuest Dissertations and Theses, 2008Co-Authors: Cristina J BungetAbstract:Tube hydroforming is a manufacturing process which applies controlled internal pressure and axial feed to expand the tube to desired shapes. The main advantages are: part consolidation, weight reduction, fewer secondary operations, and tighter tolerances. However, it has disadvantages due to many variables, such as loading paths, material formability, and tribological conditions, which limit its applicability and influence parts failure (excessive thinning, wrinkling, buckling or bursting). This research presents ultrasonic technology as a method of improving formability and tribological conditions. The superimposing of ultrasonic oscillations was already proved to have benefits for other metal forming processes, such as reduction in the forming load and frictional stresses. The objectives of this research work are to develop an analytical model to predict the state of stress and strain for the tube expansion under internal pressure and friction conditions, for ultrasonic and non-ultrasonic processes, observe the effects of the vibration on the deformation pattern, design a set of tooling and conduct experiments. An analytical model was derived for both conventional and ultrasonic tube hydroforming processes, using equilibrium of forces, geometric relationships, material flow law and yield criterion. The square dies were chosen for this study, due to the simplicity of plane strain conditions. In conventional process the tube is expanded under internal pressure in the presence of friction. In the ultrasonic process, vibrations are imposed on the die, resulting in alternating gaps at the die/tube interface. The gaps open and close after each oscillation. Two different states of stress alternate during one oscillation in an element of the tube wall. The analytical model was used to predict the internal pressure required, the Corner Radius, the thickness distribution, and the state of stress and strain. For the conventional process, the influence of some parameters on the deformation pattern and the forming load, such as strain hardening and friction conditions, was studied. Lower friction coefficient is required for more uniform tube wall thickness and lower pressure. In the ultrasonic process, more uniform thickness distribution and state of stress and strain were predicted, as compared to the classical process. When the internal pressure is maintained, the Corner Radius obtained is Smaller. The reduction in the Corner Radius was between 2.4 and 9%. More uniform thickness and less thinning, as well as Smaller Corner Radius, indicate improvement of the formability of the material. If ultrasonic oscillations are used and the pressure exerted on the tube due to vibration is less than a critical value (equal to the internal pressure), there is a decrease in the maximum internal pressure needed for the same expansion. The most effective ultrasonic pressure is 0.1 MPa. Finite element method was used to approximate the ultrasonic pressure and to design a set of tooling for ultrasonic process at 20 kHz. Four models were proposed and analyzed for three square die sizes. Modal analysis was used to observe the die vibration and the possible useful effects on the forming process. Harmonic response analyses were conducted to evaluate the amplitude of vibration in the deformation zone and the stress in the tooling. Based on the displacement distribution, a method of approximating the ultrasonic pressure was proposed. Most of the average pressure values were found to vary from 5 MPa to 25 MPa. In order to observe the effects of ultrasonic oscillations on tube hydroforming, experiments were conducted with and without vibration. The ultrasonic tests resulted in Smaller Corner radii as compared to the conventional test, with a reduction of 5.2-7.7%, implying increase in forming capability due to vibration.
Jennifer Johrendt - One of the best experts on this subject based on the ideXlab platform.
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Multi-objective optimization and sensitivity analysis of tube hydroforming
The International Journal of Advanced Manufacturing Technology, 2010Co-Authors: Honggang An, Daniel E. Green, Jennifer JohrendtAbstract:Tube hydroforming is a manufacturing process used to produce structural components in cars and trucks, and the success of this process largely depends on the careful control of parameters such as internal pressure and end-feed force. The objective of this work was to establish a methodology, and demonstrate its effectiveness, to determine the optimal process parameters for a tube hydroformed in a die with a square cross section. The Taguchi method was used to establish a design of virtual hydroforming experiments, and numerical simulations were carried out with the finite element code LS-DYNA®. A sensitivity analysis was also carried out with analysis of variance. Multi-objective functions that consider necking/fracture, wrinkling, and thinning were formulated, and the response surface methodology was used with the most sensitive factors to obtain a defect-free part. An objective function, based on the final Corner Radius in the part, was also included in the optimization model. The forming severity of virtual hydroformed parts was evaluated using the forming limit stress diagram and the forming limit (strain) diagram. Finally, the normal-boundary intersection method and the L _2 norm were used to obtain the Pareto-optimal solution set and the optimal solution within this set, respectively. The hydroforming process for this part was also optimized using the commercial optimization software LS-OPT®, with two different single-objective algorithms. However, the optimum load path predicted with the proposed methodology was shown to achieve a Smaller Corner Radius. The proposed optimization technique helped to define a process window that leads to a robust manufacturing process and improved part quality.