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Accessible Unlicensed Requires Authentication Published by De Gruyter December 24, 2015

Sensitivity analysis of the residual stress state in friction stir welding of high strength aluminum alloy

Sensitivitätsanalyse des Eigenspannungszustandes einer rührreibgeschweißten hochfesten Aluminiumlegierung
Marcel Bachmann, Michael Rethmeier and Chuan Song Wu
From the journal Materials Testing

Abstract

In this paper, the friction stir welding process was numerically investigated for 6 mm thick aluminum alloy AA2024-T3. The finite element software COMSOL Multiphysics was used to calculate the transient thermal field during welding and the mechanical reaction depending on different mechanical clamping conditions and hardening models subsequently. A thermal pseudo-mechanical (TPM) heat source was implemented. Softening effects of the material due to precipitation hardening dissolution caused by the frictional heat were accounted for. The transient temperature evolution measured by thermocouple elements at various locations was compared to the numerical results. A good agreement was found for the thermal field. A sensitivity study of the mechanical models showed the strong influence of the clamping conditions and the softening model.

Kurzfassung

In diesem Artikel wird der Rührreibschweißprozess für 6 mm dicke Bleche aus AA2024-T3 numerisch untersucht. Die Finite-Elemente-Software COMSOL Multiphysics wurde eingesetzt, um sowohl das transiente Temperaturfeld während des Schweißvorgangs, als auch die entstehenden mechanischen Spannungen für verschiedene Einspannbedingungen und Verfestigungsmodelle zu berechnen. Dabei wurde eine thermo-pseudo-mechanische (TPM) Wärmequelle genutzt. Entfestigungseffekte des Materials, verursacht durch die Reibwärme bedingte Auflösung der Ausscheidungshärtung beim Rührreibschweißen, wurden berücksichtigt. Die transiente Wärmeausbildung wurde mittels Thermoelementen an verschiedenen Positionen gemessen und mit den numerisch ermittelten Werten verglichen. Dabei wurde eine gute Übereinstimmung für das Temperaturfeld erzielt. Eine Sensitivitätsstudie der genutzten mechanischen Modelle zeigt den starken Einfluss der Einspannbedingungen sowie der Entfestigung.


§Correspondence Address, Dr.-Ing. Marcel Bachmann, BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205 Berlin, Germany. E-mail:

Dr.-Ing. Marcel Bachmann, born 1984 in Berlin, is working in the BAM Federal Institute for Materials Research and Testing in Berlin, Germany in the Department “Welding Technology” since 2009. He received his diploma from the Technical University Berlin in Physical Engineering and his PhD for numerical investigations of electromagnetically-assisted high power laser beam welding processes from the same university. Currently, he is working on several projects involving numerical simulations in welding processes.

Prof. Dr.-Ing. Michael Rethmeier, born in 1972, is working in the BAM Federal Institute for Materials Research and Testing in Berlin, Germany. He is Head of the Department “Welding Technology”. He also heads the “Chair of Safety of Joined Components” at the Institute of Machine Tools and Factory Management, Technical University Berlin. Present research topics include, amongst others, innovative arc welding processes, high power laser beam welding and numerical simulations in various welding processes.

Prof. Chuan Song Wu, PhD, born in 1959, is Professor at the Institute of Materials Joining, Shandong University in Jinan, China. His research topics include numerical simulation of weld pool shapes in different welding techniques, thermal processes, vision-based intelligent detection and control of welding processes.


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Published Online: 2015-12-24
Published in Print: 2016-01-05

© 2016, Carl Hanser Verlag, München