A closed form technique to predict springback in creep age-forming

Jeunechamps, Pierre-Paul; Ho, Kar; Lin, Jianguo; Ponthot, Jean‐Philippe; Dean, Trevor

doi:10.1016/j.ijmecsci.2006.01.005

Cited by 78 publications

(51 citation statements)

References 20 publications

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“…The oven provides a heat treatment cycle to the whole apparatus at an elevated temperature, T, for a predetermined period of time, t 2 . The blank undergoes plastic deformation during this period, as the material constituents of the blank precipitate, altering the microstructure of the alloy, thereby strengthening it [1,5,22,23]. T and t 2 that characterise a heat treatment cycle are unique to each alloy and are set so that the CA-formed part will have final mechanical properties that meet the strength specification.…”

Section: A Current State-of-the-art Flexible Caf Toolmentioning

confidence: 99%

“…The latest research into CAF therefore is mainly focussed on the manufacture of aircraft wing panels. From the production of the Gulfstream IV's wing skins by Textron to the upper wing panels of the latest £270m Airbus (Toulouse, France) A380 superjumbo [3][4][5][6], CAF has already proven its practicality in the manufacturing of aircraft wing components. However, a number of challenges remain-one of which is the development of flexible CAF tools.…”

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confidence: 99%

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A method for designing lightweight and flexible creep-age forming tools using mechanical splines and sparse controlling points

Lam

Shi

Lin

et al. 2015

Int J Adv Manuf Technol

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Creep-age forming (CAF) is a proven forming technique in the aerospace industry for the production of large integrally stiffened panels. One of the most urgent issues to be addressed in CAF is the development of flexible tooling. Flexible tools already have a long-standing reputation for the economic impact they have brought to the aircraft industry. However, with the rising need to establish comprehensive springback prediction models for CAF, the need for flexible CAF tools is now stronger than ever. In this article, an existing state-of-the-art CAF tool is described followed by the introduction of a novel design concept for flexible tooling. Based on the proposed design method, which utilises mechanical splines and sparsely spaced controlling points, a proof-of-concept prototype is built and characterised using corresponding analytical and finite element models that have been developed. Three parameters that can influence forming surface error: (i) the number of control points, (ii) spaces between control points and (iii) spline thickness are identified and optimised. Finally, an integrated optimisation process for tool offsetting is introduced, and its use is demonstrated. It is confirmed that this design method can be used to make flexible CAF tools with less than ± 1 mm error (defined as vertical difference from prediction) in the forming surface. In addition, this error can eventually be compensated and thus eliminated from CA-formed parts by using the developed optimisation technique. This article provides CAF tool designers confirmed advices for making new flexible CAF tools. Lightweight and flexible CAF tools can now be constructed through the use of mechanical splines and sparse controlling points.

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Section: A Current State-of-the-art Flexible Caf Toolmentioning

confidence: 99%

mentioning

confidence: 99%

A method for designing lightweight and flexible creep-age forming tools using mechanical splines and sparse controlling points

Lam

Shi

Lin

et al. 2015

Int J Adv Manuf Technol

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“…Na fase de descarga, a placa de alumínio tende a sofrer uma recuperação elástica, sabendo que os níveis de tensões se estabelecem abaixo do limite de escoamento do material, a partir da curvatura do ferramental. Esse retorno elástico, do inglês "springback", pode ser superior a 70% da flecha inicial da chapa a ser conformada e a sua previsão é essencial para o sucesso do processo [4]. Para a aplicação correta do processo CAF é necessário conhecer, portanto, o nível de tensão (dentro do regime elástico) e também a temperatura que serão aplicados uma vez que ambos podem influenciar tanto na precipitação de partículas quanto na fluência do material, o que implica em propriedades e formas diferentes.…”

Section: Introductionunclassified

Influência Dos Parâmetros De Tratamento No Retorno Elástico Da Liga De Alumínio Aa7475 Em Condições De Conformação Sob Fluência E Envelhecimento

Araújo¹,

Silva²

2017

Anais Do Enemet - Encontro Nacional De Estudantes De Engenharia Metalúrgica, De Materiais E De Minas

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ResumoEm Conformação sob Fluência com Envelhecimento, do inglês Creep Age Forming (CAF), o material previamente solubilizado e temperado é carregado elasticamente (normalmente por flexão) e subsequentemente aquecido à temperatura de tratamento térmico de envelhecimento. Basicamente, a conformação se dá por meio de deformações provocadas simultaneamente pela tensão aplicada ao longo do tempo (fluência) e endurecimento por precipitação (envelhecimento). Sendo assim, pretende-se avaliar os efeitos dos parâmetros mencionados no retorno elástico, como tempo, temperatura, retorno elástico e propriedades mecânicas. Portanto foi avaliado, a variação do retorno elástico (springback) em função do tempo para a liga de alumínio AA7475 submetida a um carregamento de flexão durante o envelhecimento realizado em duas temperaturas diferentes (120°C e 150°C). Foi possível observar que quanto menor o tempo e a temperatura de envelhecimento, maior o retorno elástico. Portanto, quanto maior o retorno elástico da peça, mais próxima ela estará do seu formato original antes da conformação [1]. Em relação à dureza, foi observado que quando o material é submetido a uma temperatura de 120°C obtém-se um aumento significativo de dureza Vickers com o passar do tempo (atribuída a precipitação refinada) e a 150°C não ocorre esse aumento significativo dessa propriedade mecânica (atribuído a precipitação mais grosseira). Palavras-chave: Conformação; Envelhecimento; Fluência; Retorno elástico. INFLUENCE OF TREATMENT PARAMETERS IN SPRINGBACK OF ALUMINUM ALLOY AA7475 IN TERMS OF CREEP AGE FORMING AbstractIn Creep Age Forming (CAF), the material, previously solubilized and seasoned, is loaded elastically (usually by flexion) and subsequently it is heated to temperature of heat treatment. Basically, the conformation happens to deformations caused by tension that are applied simultaneously over time (creep) and by precipitation hardening (aging). Thus, we intend to evaluate the effects of the parameters mentioned in springback, as time, temperature, springback and mechanical properties. Therefore was evaluated, the variation of springback versus time for the aluminum alloy AA7475 subjected to a load bending achieved during aging at two different temperatures (120 °C and 150 ° C). It was possible to see that the smaller time and aging temperature, the bigger the springback. Therefore, the greater the elastic return of the part, the closer it will be to its original shape before the conformation [1]. Regarding the hardness, it was observed that when the material is subjected to a temperature of 120°C, it gains a significant increase of Vickers hardness with over time (assigned to fine precipitation) and with 150°C, it doesn't occur a significant increase this mechanical property (assigned the grossest precipitation).

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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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A closed form technique to predict springback in creep age-forming

Cited by 78 publications

References 20 publications

A method for designing lightweight and flexible creep-age forming tools using mechanical splines and sparse controlling points

A method for designing lightweight and flexible creep-age forming tools using mechanical splines and sparse controlling points

Influência Dos Parâmetros De Tratamento No Retorno Elástico Da Liga De Alumínio Aa7475 Em Condições De Conformação Sob Fluência E Envelhecimento

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

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