Modeling of AlMg Sheet Forming at Elevated Temperatures
The process limits of aluminum sheet forming processes can be improved by control-ling
local flow behavior by means of elevated temperatures and temperature gradients. In order
to accurately model the deep drawing or stretching of aluminum sheet at elevated temperatures,
a model is required that incorporates the temperature and strain-rate dependency of the ma-terial.
In this paper two models are compared: a phenomenological material model in which
the parameters of a Ludwik–Nadai hardening curve and a power law strain-rate influence are
made temperature dependent and a physically-based model according to Bergstrš om. The model
incorporates the influence of the temperature on the flow stress and on the hardening rate and
includes dynamic recovery aspects. Although both models can be fitted quite well to monotonic
tensile tests of an AA 5754-O alloy, large differences appear if strain rate jumps are applied.
Subsequent simulation of cylindrical cup deep drawing shows a large influence of friction and
the shape of the yield surface.
Anton H. VAN DEN BOOGAARD, Pieter Jan BOLT, Robert J. WERKHOVEN
Reçu le 1 juillet 2001.
Accepté le 30 octobre 2001.
Aluminum, Thermo-mechanical Forming, Deep Drawing, Material Model, Finite Element Method