Modelling of springback in creep forming thick aluminum sheets

Ho, Kar; Lin, Jianguo; Dean, Trevor

doi:10.1016/s0749-6419(03)00078-0

Cited by 122 publications

(85 citation statements)

References 33 publications

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“…Eberl et al verified the feasibility of CAF in forming the commercial aircraft stiffened plates via practical experiments [3]. One of the key problems during CAF is the springback because the plastic strain level is very low and the elastic strain maintains a high level after forming [4]. The comparison of springback with different plates, including flat, beam stiffened, waffle and isogrid Zhao et al [18] simulated the EMIF process of tubes, and analyzed the influence of coil path and coil overlap rate on the forming results.…”

Section: Introductionmentioning

confidence: 99%

Guideline for Forming Stiffened Panels by Using the Electromagnetic Forces

Tan

Zhan

Liu

2016

Metals

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Electromagnetic forming (EMF), as a high-speed forming technology by applying the electromagnetic forces to manufacture sheet or tube metal parts, has many potential advantages, such as contact-free and resistance to buckling and springback. In this study, EMF is applied to form several panels with stiffened ribs. The distributions and variations of the electromagnetic force, the velocity and the forming height during the EMF process of the bi-directional panel with gird ribs are obtained by numerical simulations, and are analyzed via the comparison to those with the flat panel (non-stiffened) and two uni-directional panels (only with X-direction or Y-direction ribs). It is found that the electromagnetic body force loads simultaneously in the ribs and the webs, and the deformation of the panels is mainly driven by the force in the ribs. The distribution of force in the grid-rib panel can be found as the superposition of the two uni-directional stiffened panels. The velocity distribution for the grid-rib panel is primarily affected by the X-directional ribs, then the Y-directional ribs, and the variation of the velocity are influenced by the force distribution primarily and secondly the inertial effect. Mutual influence of deformation exists between the region undergoing deformation and the deformed or underformed free ends. It is useful to improve forming uniformity via a second discharge at the same position. Comparison between EMF and the brake forming with a stiffened panel shows that the former has more advantages in reducing the defects of springback and buckling.

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Section: Introductionmentioning

confidence: 99%

Guideline for Forming Stiffened Panels by Using the Electromagnetic Forces

Tan

Zhan

Liu

2016

Metals

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“…CAF simultaneously strengthens the part and changes its shape, resulting in a one-step forming and heat treatment process that can largely increase the mechanical properties. With the increasingly high performance requirements on the formed components, the aims of study on CAF should not only satisfy the needs of precision shape forming, but also meet the needs of high performance of the formed products [3][4][5]. However, controlling material performance is very difficult due to the presence of heavy interaction between creep and aging in the CAF process.…”

Section: Introductionmentioning

confidence: 99%

Effect of Creep Aging Process on Microstructures and Properties of the Retrogressed Al-Zn-Mg-Cu Alloy

Zhan

2016

Metals

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Abstract:The creep aging behaviors of retrogressed Al-Zn-Mg-Cu alloy were studied by uniaxial tensile creep tests at 140 • C. The effects of creep aging time and applied stress on microstructures and properties of the studied alloy were investigated by using transmission electron microscope (TEM), hardness, and corrosion resistance tests. Results show that the effects of the creep aging process on microstructures and properties are significant. The size of matrix precipitate (MPt), distance between MPts, width of precipitate-free zone (PFZ), and distance between grain boundary precipitates (GBPs) increase with the increase of creep aging time and applied stress. With the increase of creep aging time and applied stress, the corrosion resistance of the studied alloy improved. After creep aging for 20 h, the electrical conductivity varied with different applied stress from 35.99% to 37.24% International Annealed Copper Standard (IACS), and the exfoliation corrosion (EXCO) resistance increased to the corrosion rating of "EB", which express slight surface corrosion. Compared with the traditional retrogression and re-aging process (RRA), the retrogression and creep aging process (RCA) can increase the MPt size, widen the precipitates distribution, narrow the PFZ width, and enhance the corrosion resistance while offering the hardness comparable to that of the RRA process.

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“…Many constitutive models for CAF have been developed to predict the mechanical properties and form shape so that a specific strength and part shape can be achieved [10,11]. Zhan et al [12] proposed a set of mechanism-based unified creep-aging constitutive equations to model creep deformation and the evolutions of precipitate size and dislocation density, which control the amount of age hardening, solid solution hardening and work hardening during creep-ageing.…”

Section: Introductionmentioning

confidence: 99%

Constitutive modelling of creep-ageing behaviour of peak-aged aluminium alloy 7050

Yang

Lam

Shi

et al. 2015

MATEC Web of Conferences

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Abstract. The creep-ageing behaviour of a peak-aged aluminium alloy 7050 was investigated under different stress levels at 174• C for up to 8 h. Interrupted creep tests and tensile tests were performed to investigate the influences of creep-ageing time and applied stress on yield strength. The mechanical testing results indicate that the material exhibits an over-ageing behaviour which increases with the applied stress level during creep-ageing. As creep-ageing time approaches 8 h, the material's yield strength under different stress levels gradually converge, which suggests that the difference in mechanical properties under different stress conditions can be minimised. This feature can be advantageous in creep-age forming to the formed components such that uniformed mechanical properties across part area can be achieved. A set of constitutive equations was calibrated using the mechanical test results and the alloy-specific material constants were obtained. A good agreement is observed between the experimental and calibrated results.

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Modelling of springback in creep forming thick aluminum sheets

Cited by 122 publications

References 33 publications

Guideline for Forming Stiffened Panels by Using the Electromagnetic Forces

Guideline for Forming Stiffened Panels by Using the Electromagnetic Forces

Effect of Creep Aging Process on Microstructures and Properties of the Retrogressed Al-Zn-Mg-Cu Alloy

Constitutive modelling of creep-ageing behaviour of peak-aged aluminium alloy 7050

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