Constitutive modelling and springback prediction for creep age forming of 2124 aluminium alloy

This paper presents an extension of the Ramaswamy, Stouffer, and Laflen unified elastic–viscoplastic theory which uses internal state variables to represent a strain rate insensitive aluminium alloy namely 7050-T7451 alloy. The model constants are evaluated from the results of a uniaxial tensile test, with strain hold at saturation, and a fatigue loop. Strain holds in the saturated region of tensile monotonic curves resulted in significant amounts of stress relaxation. The material response is cyclically stable and reveals a strong Bauschinger effect. There is a significant reduction in the yield stress between the initial yield and the subsequent tensile yield stress observed after a fully reversed fatigue cycle. All of these material characteristics were predicted successfully.

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A Research on the Creep Age Forming of 2524 Aluminum Alloy: Springback, Mechanical Properties, and Microstructures

Advances in Mechanical Engineering ◽

10.1155/2014/707628 ◽

2014 ◽

Vol 6 ◽

pp. 707628 ◽

Cited By ~ 4

Author(s):

Lihua Zhan ◽

Sige Tan ◽

Youliang Yang ◽

Minghui Huang ◽

Wenqi Shen ◽

...

Keyword(s):

Mechanical Properties ◽

Aluminum Alloy ◽

Prediction Models ◽

Stress Gradient ◽

Sheet Thickness ◽

Linear Regression Method ◽

Forming Process ◽

Bending Radius ◽

Springback Prediction ◽

Creep Age Forming

A series of orthogonal tests have been designed to investigate the combined effects of aging temperature, time, predeformation, and part thickness features on the springback of creep age forming of 2524 aluminum alloy sheets. Two springback prediction models containing the four process parameters mentioned above are developed based on experimental results and the multiple linear regression method. The comparisons of predicted and experimental values of springback yield good agreement. The dependence of springback on stress gradient across the thickness of sheet is examined in detail, showing that springback increases with the decrease in stress gradient while maintaining the ratio of bending radius to sheet thickness ( R0/ H) as constant. In addition to springback, the mechanical properties and microstructural evolution are also researched. In the creep age forming process, the compression side of the sheet has higher mechanical properties and is characterized by more and finer precipitates in grains as compared to tension side.

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Experimental and numerical modelling and simulation of the creep age forming of aeronautic panels AA7XXX aluminium alloy

Advances in Materials and Processing Technologies ◽

10.1080/2374068x.2016.1147764 ◽

2016 ◽

Vol 2 (1) ◽

pp. 1-20 ◽

Cited By ~ 2

Author(s):

F. C. Ribeiro ◽

B. T. Scarpin ◽

G. F. Batalha

Keyword(s):

Numerical Modelling ◽

Aluminium Alloy ◽

Modelling And Simulation ◽

Creep Age Forming

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Investigation of Tensile and Compressive Creep Behaviour of AA2050-T34 during Creep Age Forming Process

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.716.323 ◽

2016 ◽

Vol 716 ◽

pp. 323-330 ◽

Cited By ~ 1

Author(s):

Yong Li ◽

Zhusheng Shi ◽

Yo Lun Yang ◽

Jian Guo Lin

Keyword(s):

Power Law ◽

Creep Behaviour ◽

Primary Creep ◽

Constitutive Modelling ◽

Ageing Process ◽

Forming Process ◽

Creep Equation ◽

Compressive Creep ◽

Creep Stress ◽

Creep Age Forming

The tensile and compressive creep behaviour of aluminium alloy 2050 with T34 initial temper (AA2050-T34) during creep-ageing process has been experimentally investigated and analysed in detail. Both tensile and compressive creep-ageing tests under various stress levels (ranging from 100 MPa to 187.5 MPa) have been carried out at a temperature of 155 °C for 18 hours. The results show that creep strains under tensile stresses are much larger than those under the same levels of compressive stresses and a new “double primary creep feature” with five-stage creep behaviour has been observed in the alloy during the creep-ageing tests. The conventional power-law creep equation was applied to analyse the new creep behaviour of the alloy at the steady-state creep stage. Furthermore, the power-law relationship between the applied stress and the corresponding creep strain rate was found to be effective in all creep-ageing stages of the alloy and was used for further analysis. These analyses indicate that the dislocation and diffusion mechanisms may both contribute to this new creep behaviour and may play different roles in different creep-ageing stages. Moreover, the evolution of the creep resistance or threshold creep stress of the alloy during the creep-ageing process was quantitatively investigated by the proposed relationship. These results help to not only understand the new creep behaviour of AA2050-T34 during the creep-ageing process, but also facilitate further constitutive modelling of this new creep behaviour for its creep age forming applications.

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