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Lecture

Cyclic material behavior of aluminum wrought alloys considering heat treatment and prestrain

Thursday (07.11.2019)
11:25 - 11:45
Part of:


The exploitation of the strength properties shown by the materials under service loading conditions is fundamental for the mass reduction in case of lightweight design. This can be motivated by several factors such as material costs, or aspects like the legal issues related to CO2 emissions, that can be limited by minimizing the total weight of transportations. For wrought aluminum alloys, this is possible thanks to new technologies like the hot forming, used for the production of inhomogeneous parts with localized optimized microstructures. On the other hand, this process leads to property gradients inside of the material, which have to be taken into account for the formulation of a high quality fatigue approach. Therefore, in order to describe correctly the local material properties, a strain based fatigue approach is chosen, with main focus on the description of the local cyclic material properties to be used for numerical simulation, fundamental for the quality of the assessment. In case of aluminum wrought alloys, the discussion about the possibility to use the well-known strain-life curve for describing the fatigue strain-life of the material is also still ongoing. In this work, the process parameters of the hot forging process on aluminum wrought alloys are investigated by means of different degrees of deformation and heat treatments, and the quality of the resulting strain-life curve, according to Coffin-Manson-Basquin, and of the fatigue-life curve are discussed. Furthermore, the cyclic stress-stain curve that describes the material properties can be derived from the strain-life curve by use of the compatibility conditions, according to Ramberg-Osgood. Due to the different strain-life curves, the resulting stress-strain curve is influence by the choice of the strain-life curve model, and this effect is finally quantified.

Speaker:
Andreas Maciolek
Fraunhofer Institute for Structural Durability and System Reliability LBF
Additional Authors:
  • Julian Bernhard
    Fraunhofer Institute for Structural Durability and System Reliability LBF
  • Prof. Tobias Melz
    Fraunhofer Institute for Structural Durability and System Reliability LBF