Process design for multi-stage stretch forming of aluminium alloy aircraft skin

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.

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Optimization on springback reduction in cold stretch forming of titanium-alloy aircraft skin

Transactions of Nonferrous Metals Society of China ◽

10.1016/s1003-6326(10)60654-1 ◽

2010 ◽

Vol 20 (12) ◽

pp. 2350-2357 ◽

Cited By ~ 12

Author(s):

De-hua HE ◽

Dong-sheng LI ◽

Xiao-qiang LI ◽

Chao-hai JIN

Keyword(s):

Titanium Alloy ◽

Stretch Forming ◽

Aircraft Skin ◽

Springback Reduction

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Reduction of Stages in Multi-Stage Metal Forming Process Based on Numerical Optimization in Conjunction with FE Simulation

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.340-341.767 ◽

2007 ◽

Vol 340-341 ◽

pp. 767-772

Author(s):

Ryutaro Hino ◽

Akihiko Sasaki ◽

Fusahito Yoshida ◽

Vassili V. Toropov

Keyword(s):

Design Optimization ◽

Process Design ◽

Metal Forming ◽

Numerical Optimization ◽

Fe Simulation ◽

Design Technique ◽

Forming Process ◽

Multi Stage ◽

Metal Forming Process ◽

Stage Process

In this study, a new simulation-based design technique for multi-stage metal forming process is developed with special emphasis on reduction of stages in the process. The developed design technique is an iterative design optimization, which is based on response-surface-based numerical optimization and finite element analysis of the process. The design procedure starts with the initial rough process design. To eliminate one stage in the multi-stage process, the new optimum process design is determined based on the former process design by using numerical optimization in conjunction with FE simulation. This design optimization step is repeated, reducing the stages one by one, until the possible minimum number of stages is reached. The developed design technique is applied to stage reduction of a 3-stage axisymmetric forging process of aluminum billet. We can confirm that a new 2-stage process design is determined successfully and the developed design optimization technique is effective to reduce stages in multi-stage forming process.

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