The basis of this work is the lifetime characterisation of different non-ferrous alloys (Al, Cu, Ni) under thermomechanical fatigue (TMF). The alloys employed are three hypoeutectic aluminium alloys (AlSi5MgCu0.5, AlSi7MgCu0.5, AlSi8Cu3), two copper alloys (CuCoBe, CuCo2Be) and two nickel alloys (Ni200/201, IN718). The applications of these alloys is quite divers the aluminium alloys are used for cylinder heads, the copper alloys for components in steel mills and the nickel alloys in turbines. Even though they are employed in quite different applications they have in common that they operate under varying temperatures resulting in thermomechanical fatigue. The analysis and comparison of the results of systematic tests regarding mechanical and thermal influences in thermomechanical fatigue allows defining the material potentials as well as material models describing the fatigue lifetime under thermal loading conditions. Today sophisticated components like turbine disks of cylinder heads are designed using finite-element methods (FEM) to compute their mechanical and thermal loads. Based on these results it is possible to derive the local damage in a component and as a consequence its lifetime. A further point dealt with the application of material- and fatigue models which are used to describe the results of the low-cycle fatigue (LCF) and TMF results in the simulation. The findings show that the applicability of conventional empirical models is limited because of the damage behaviour. Based on these observations a new approach has been developed. It is referenced to stress and strain which includes - in addition to conventional models - also the influence of the oxidation and the creep. This model shows a clear improvement especially describing the thermomechanical fatigue lifetime. In addition the model can be calibrated with a few tests and leads therefore to time and cost savings.
|Translated title of the contribution||Development of a model to describe the lifetime behaviour of non-ferrous alloys (Al, Cu, Ni) under thermomechanical loading|
|Publication status||Published - 2009|
Bibliographical noteembargoed until null
- Thermomechanical fatigue
- low cycle fatigue