Robust Design of Aircraft Skin Stretch Forming Process Based on Transmitted Variance Model

2011 ◽  
Vol 47 (01) ◽  
pp. 145
Author(s):  
Lijuan SHEN
Keyword(s):  
Robust Design ◽  
Stretch Forming ◽  
Forming Process ◽  
Variance Model ◽  
Aircraft Skin ◽  
Skin Stretch ◽  
Skin Stretch Forming

Aircraft Skin Stretch-Forming Die Light-Weight Design Using Topology Optimization

2011 ◽  
Vol 697-698 ◽  
pp. 600-603 ◽  
Author(s):  
Ji Hong Zhu ◽  
H. Wang ◽  
W.H. Zhang ◽  
X.J. Gu
Keyword(s):  
Numerical Simulation ◽  
Topology Optimization ◽  
Topology Design ◽  
Surface Load ◽  
Light Weight ◽  
Stretch Forming ◽  
Weight Design ◽  
Aircraft Skin ◽  
Skin Stretch ◽  
Skin Stretch Forming

The purpose of this paper is to use the topology optimization method to solve the light-weight design problem of large aircraft skin stretch-forming die. The platform of ABAQUS is firstly used for numerical simulation of skin stretch-forming. And the surface load conditions are therefore obtained. The topology optimization is carried out accordingly to maximize the structural stiffness with the material properties and the boundary conditions properly defined. Referring to the obtained topology design, the optimal structure is reconstructed and then evaluated by the non-linear numerical simulation of stretch-forming. Compared with the traditional design, the numerical results have shown that the topology design can improve the stiffness and strength of the stretch-forming die significantly.

Numerical Analysis for the Multi-Point Stretch Forming Process of Aircraft Skin Panel

2011 ◽  
Vol 109 ◽  
pp. 504-508 ◽  
Author(s):  
Yu Shan Deng ◽  
Yuan Yao ◽  
Shao Hui Wang
Keyword(s):  
Numerical Analysis ◽  
Numerical Simulations ◽  
Equivalent Strain ◽  
Stretch Forming ◽  
Forming Process ◽  
Outer Skin ◽  
Free Length ◽  
Aircraft Skin ◽  
A New Technique ◽  
Elastic Cushion

Multi-point stretch forming (MPSF) is a new technique to form aircraft outer skin panel. Since multi-point die is composed by the discrete punches, the result of the MPSF aircraft outer skin panel need to study in depth. The thickness of elastic cushion and free length are two important factors to affect the accuracy, and they must be chosen reasonably. A series of numerical simulations on typical MPSF processes were carried out to an aircraft outer skin panel part. The results show that the thicker the elastic cushion is, the more valid the dimple will be suppressed .The longer free length is, the smaller the equivalent strain and thinning and more uniform the distribution of thickness will be. When the free length is shorter, the degree of effect is relatively obvious on the equivalent strain and thinning and the distribution of thickness; when the free length is longer than a certain value, the degree of effect is small.

Design and Optimization of Loading Trajectory for S-Skin Stretch Forming Process by Simulation

2011 ◽  
Vol 704-705 ◽  
pp. 1363-1369
Author(s):  
Yan Min Zhang ◽  
Xiao Qiang Li ◽  
Ke Xing Song
Keyword(s):  
Mathematics Model ◽  
Stretch Forming ◽  
Forming Process ◽  
Primary Methods ◽  
Design And Optimization ◽  
Design Variables ◽  
Loading Trajectory ◽  
Set Up ◽  
Skin Stretch Forming ◽  
Thinning Rate

Stretch forming is one of the primary methods in skin forming process. Uniform strain distribution and springback are main factors which affect the precision of air skin. In the article the stretch forming process based on S-skin was analyzed. Firstly the parameters ranges of the loading trajectory were designed through the analytic method. Secondly the initial loading trajectory was optimized through finite element numerical simulation. The optimization processes was performed through FET software integrated with the optimization arithmetic. The motion parameters of jaw and machine’s instructions were selected as design variables. Optimization mathematics model was set up which objective is to reduce springback and improve the strain distributes uniform degree. During optimization the maximum main strain and thickness thinning rate of elements were restricted in permissive range. The forming degree of each stage was rational distributed, and the reasonable loading trajectory was founded. The result shows that the reasonable loading trajectory is including pre-stretch, wrap, press and after stretch. After optimization the strain distributes uniformly and the maximum main strain is between 3％～5％. The maximum stretching rate which appears in the shoulders area is less than 6%. In the concave area in which the insufficiency deforming can be occurred easily the strain achieves about 3%, and the deformation is enough. After optimization the unloading springback is decreased distinctly. The average springback of all elements is 0.47mm which reduces 30% compare with before optimization. The result meets the manufacture requirement.

A New Stretch-Forming Process Based on Loading at Discrete Points and its Numerical Investigation

2013 ◽  
Vol 423-426 ◽  
pp. 737-740
Author(s):  
Zhong Yi Cai ◽  
Mi Wang ◽  
Chao Jie Che
Keyword(s):  
Sheet Metal ◽  
Three Dimensional ◽  
Discrete Point ◽  
Stretch Forming ◽  
Sheet Metal Part ◽  
Metal Part ◽  
Forming Process ◽  
Loading Trajectory ◽  
New Process ◽  
Forming Defects

A new stretch-forming process based on discretely loading for three-dimensional sheet metal part is proposed and numerically investigated. The gripping jaw in traditional stretch-forming process is replaced by the discrete array of loading units, and the stretching load is applied at discrete points on the two ends of sheet metal. By controlling the loading trajectory at the each discrete point, an optimal stretch-forming process can be realized. The numerical results on the new stretch-forming process of a saddle-shaped sheet metal part show that the distribution of the deformation on the formed surface of new process is more uniform than that of traditional stretch-forming, and the forming defects can be avoided and better forming quality will be obtained.

Flexible Stretch Forming Technology for Sheet Metal Based on Discrete-Gripper and Multi-Point Die

2014 ◽  
Vol 556-562 ◽  
pp. 460-463 ◽  
Author(s):  
Xue Chen ◽  
Ming Zhe Li ◽  
Wen Hua Liu ◽  
Zhi Qiang Hou
Keyword(s):  
Sheet Metal ◽  
Experimental Results ◽  
Shape Error ◽  
Stretch Forming ◽  
Forming Process ◽  
Structural Composition ◽  
Forming Technology ◽  
Working Principle ◽  
Material Utilization

To solve the problem of low material utilization in traditional stretch forming process, a flexible stretch forming method was proposed, which can be realized by interaction of the multi-point stretch forming die with discrete-gripper stretch forming machine. The principle and characteristics of sheet metal flexible stretch forming technology was introduced, structural composition and working principle of the multi-point stretch forming die and discrete-gripper stretch forming machine were expounded, and the technology experiments was carried out with a self-designed flexible stretch forming technology equipment for sheet metal. The experimental results indicate that structure of multi-point stretch forming die and discrete-gripper stretch forming machine are reasonable, and flexible stretch forming technology can be realized by above-mentioned die and machine, stretch forming parts has a good quality and its shape error can satisfy requirements of production.

Influence of Element Number on Shape Accuracy in Multi-Point Stretch Forming of Air Craft

2011 ◽  
Vol 130-134 ◽  
pp. 2240-2244
Author(s):  
Jing Ling Wang ◽  
Zhong Yr Cai ◽  
Mine Zhe Li ◽  
Hui Yang
Keyword(s):  
Flexible Manufacturing ◽  
Three Dimensional ◽  
Great Influence ◽  
Stretch Forming ◽  
Forming Process ◽  
Shape Accuracy ◽  
Part Quality ◽  
Die Surface ◽  
Dimensional Shape ◽  
Element Number

Multi-point stretch forming is a flexible manufacturing technique for three-dimensional shape forming of craft skin. Its die surface is constructed by many pairs of matrices of elements whose height is controlled by computer. It uses the curved surface of elements instead of the die surface. The element numberis an important parameter because it has great influence on the part quality. This paper simulates the forming process of paraboloid part and saddle-shaped part with different number of elements and studies the influence of element number on the shape accuracy of the part .That will provides guidance for the application of multi-point stretch forming.

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