Residual stress and distortion modeling on aeronautical aluminum alloy parts for machining sequence optimization

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ORIGINAL ARTICLE

Residual stress and distortion modeling on aeronautical aluminum alloy parts for machining sequence optimization Mikel Casuso 1

&

Roberto Polvorosa 2 & Fernando Veiga 1 & Alfredo Suárez 1 & Aitzol Lamikiz 3

Received: 30 March 2020 / Accepted: 21 July 2020 / Published online: 21 August 2020 # Springer-Verlag London Ltd., part of Springer Nature 2020

Abstract The manufacture of machined components for the aeronautics industry often involves the removal of large quantities of material, while the stringent demands on quality require special care to be taken during the manufacturing process. For most components of this kind, the principal source of distortion is the relaxation of residual stress after the earlier manufacturing processes. In this paper, the problem is addressed through modeling and simulating the final displacement fields obtained after different machining sequences of an aeronautic turbine component, in order to determine the optimum machining sequence among the options that lead to the same final part. Some of the main problems associated with this issue are also addressed, such as the high computational cost and time needed for simulations and expensive equipment needed for residual stress measurement. The level-set technique is employed, which decreases remeshing needs, while affordable nondestructive techniques for measuring residual stress are developed, providing qualitative information that is especially useful in industrial environments. Keywords Modeling methodology . Machining distortion . Residual stress . Finite element analysis . Al 7075 alloy

1 Introduction During and after the machining process, the machined parts undergo unwanted distortions for a number of reasons. Among these, we should give special mention to the release of inherent

* Mikel Casuso [email protected] Roberto Polvorosa [email protected] Fernando Veiga [email protected] Alfredo Suárez [email protected] Aitzol Lamikiz [email protected] 1

TECNALIA, Basque Research and Technology Alliance (BRTA), 20009 Donostia/San Sebastián, Spain

2

Aeronautics Advanced Manufacturing Center CFAA, 48170 Zamudio, Spain

3

Department of Mechanical Engineering, University of the Basque Country (UPV/EHU), 48013 Bilbao, Spain

or bulk residual stress generated during upstream processes including forming (forging, extrusion, rolling) and eventual heat treatments such as quenching, which seek to achieve the desired mechanical properties [1]. In addition, the machining-induced residual surface stress of the part [2] and the stresses and forces applied by clamping systems can also lead to distortions in certain parts [3, 4], as well as cutting forces or vibrations from the tool. Nevertheless, relaxation of inherent residual stresses is the most critical source of distortion during the machining process for monolithic aircraft components made of aluminum alloy [4]. Residual stress is the stress that remains in an ingot once the cause thereof disappears [5]. The ingot maintains an equilib