Tube Hydroforming Process Optimal Design by Improved Dynamic Programming

2011 ◽  
Author(s):  
Zi Qiang Sheng
Keyword(s):  
Dynamic Programming ◽  
Optimal Design ◽  
Tube Hydroforming ◽  
Hydroforming Process ◽  
Improved Dynamic Programming

Optimization of Tube Hydroforming Process Using Probabilistic Constraints on Failure Modes

2011 ◽  
Vol 62 ◽  
pp. 21-35 ◽  
Author(s):  
Anis Ben Abdessalem ◽  
A. El Hami
Keyword(s):  
Failure Modes ◽  
High Reliability ◽  
Thickness Distribution ◽  
Tube Hydroforming ◽  
Forming Limit Diagram ◽  
Plastic Instability ◽  
Probabilistic Constraints ◽  
Forming Limit ◽  
Reliability Based Design ◽  
Hydroforming Process

In metal forming processes, different parameters (Material constants, geometric dimensions, loads …) exhibits unavoidable scatter that lead the process unreliable and unstable. In this paper, we interest particularly in tube hydroforming process (THP). This process consists to apply an inner pressure combined to an axial displacement to manufacture the part. During the manufacturing phase, inappropriate choice of the loading paths can lead to failure. Deterministic approaches are unable to optimize the process with taking into account to the uncertainty. In this work, we introduce the Reliability-Based Design Optimization (RBDO) to optimize the process under probabilistic considerations to ensure a high reliability level and stability during the manufacturing phase and avoid the occurrence of such plastic instability. Taking account of the uncertainty offer to the process a high stability associated with a low probability of failure. The definition of the objective function and the probabilistic constraints takes advantages from the Forming Limit Diagram (FLD) and the Forming Limit Stress Diagram (FLSD) used as a failure criterion to detect the occurrence of wrinkling, severe thinning, and necking. A THP is then introduced as an example to illustrate the proposed approach. The results show the robustness and efficiency of RBDO to improve thickness distribution and minimize the risk of potential failure modes.

scholarly journals Numerical investigation of plastic flow and residual stresses generated in hydroformed tubes

2021 ◽  
pp. 146442072198974
Author(s):  
A Ktari ◽  
A Abdelkefi ◽  
N Guermazi ◽  
P Malecot ◽  
N Boudeau
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Finite Element Model ◽  
Plastic Flow ◽  
Tube Hydroforming ◽  
Three Dimensional ◽  
Element Model ◽  
Tube Cross Section ◽  
Straight Wall ◽  
Hydroforming Process

During tube hydroforming process, the friction conditions between the tube and the die have a great importance on the material plastic flow and the distribution of residual stresses of the final component. Indeed, a three-dimensional finite element model of a tube hydroforming process in the case of square section die has been performed, using dynamic and static approaches, to study the effect of the friction conditions on both plastic flow and residual stresses induced by the process. First, a comparative study between numerical and experimental results has been carried out to validate the finite element model. After that, various coefficients of friction were considered to study their effect on the thinning phenomenon and the residual stresses distribution. Different points have been retained from this study. The thinning is located in the transition zone cited between the straight wall and the corner zones of hydroformed tube due to the die–tube contact conditions changes during the process. In addition, it is clear that both die–tube friction conditions and the tube bending effects, which occurs respectively in the tube straight wall and corner zones, are the principal causes of the obtained residual stresses distribution along the tube cross-section.

Experimental Researches upon Changes of a Pipe's Roughness after Hydroformation

2013 ◽  
Vol 371 ◽  
pp. 111-115
Author(s):  
Bogdan Constantin Vaceanu ◽  
Gheorghe Nagit ◽  
Vasile Huian
Keyword(s):  
Surface Roughness ◽  
Tube Hydroforming ◽  
Work Piece ◽  
Copper Pipe ◽  
Work Area ◽  
The Coefficient Of Friction ◽  
Hydroforming Process ◽  
Aluminum Pipe ◽  
Experimental Researches

Surface roughness was studied in the tube hydroforming process, considering the quality of the material and the coefficient of friction between the work piece and die. Other researchers have studied the surface roughness to the front of an aluminum pipe [. The aim of this work was to analyze changes in a copper pipe roughness occurred after hydroforming process with fluid. Effects of changing roughness were studied, following the deformation of the material in the work area and roughness changes occurring in the material flow. After achieving hydroforming process, the surface roughness was measured by electron microscopy SEM in different areas of the hydro formed tube. After hydroforming process, an increase of surface roughness in connection areas of the mold to the curvature and the transverse direction of the pipe.

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