PSI - Issue 48

Oleh Yasniy et al. / Procedia Structural Integrity 48 (2023) 149–154 Yasniy et al/ Structural Integrity Procedia 00 (2023) 000–000

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In the article by Yasniy et al. (2010), the modelling of discontinuous deformation in Al-6%Mg alloy was shown. It is known that with the constant development of artificial intelligence, it is advisable to use machine learning methods to predict deformations. In particular, in the paper by Javaheri et al. (2020), deformation using computer vision algorithms was analysed, and the data obtained was used to train neural networks to estimate the mechanical properties of steel. In addition, in the paper by Ghatak et al. (2018) application of an artificial neural network for the prediction of creep curves for HP40Nb micro-alloyed steel was demonstrated. Therefore, with limited experimental data, it is important to learn how to apply the neural network method to model the jump creep of AMg6 aluminium alloy. This study aimed to use various methods for investigating the jump-like creep of AMg6 aluminium alloy based on its preliminary plastic deformation during the tensile test in the soft loading mode and to compare them.

Nomenclature  p (  i ) stress  ст

stress of the beginning of the jumping process

stress increment strain increment

  e  p

creep increment  (  i ) strain of the jump Eʹ proportionality coefficient y prediction predicted element of sample y true

true value of the sample element volume of the training sample

n

2. Analysis of the jump-like creep of AMg6 aluminium alloy Tensile deformation of AMg6 alloy under mild loading conditions is accompanied by intermittent yielding (jump-like deformation), which is recorded graphically in the form of ‘steps’ on the stress-strain diagram  (  i) at the stress  p(  i) (Fig. 1).



 p (  і )



 ст

 е

 (  і )

 02



Fig. 1. Diagram of deformation of AMg6 alloy under quasi-static tension at mild loading conditions.

The section of the jump-like increase in deformation under mild loading is characterized by: the stress at the beginning of the jump process  ст, the increase in stress between the jumps  and the corresponding strain  е, the proportionality coefficient in these sections Eʹ, and the jump strain  (  i) at the corresponding stress  p(  i). With an increase in the stress  p(  i), the jump strain increases (the width of the ‘step’ in the tensile diagram). The jump strain  р also occurs under creep conditions after reaching a certain stress level on the stress-strain diagram (Fig. 2). The creep process itself is characterized by four areas on the diagram: first, the area of material strengthening, then the area of steady creep, which is accompanied by abrupt increases in strain, and the subsequent area of fracture.