In this dissertation a calculation and evaluation strategy is presented to perform a damage tolerance analysis of complex structures. The chosen example of a jet engine within windmilling fan blade off condition serves as suitable sample of a complex geometry and loading situation. The numerical illustration of this problem cannot be solved within a single program solution due to the complexity. Accordingly it will be shown which methods can be used to solve each problem and create a suitable modeling of the whole process. Thus, a modular process is to develop, which shall be adapted for more complex models and loads without major difficulties if desired. The result will only depend on the quality of the used models.
With the help of the new presented MMM and further developed DIH-Hypothesis a FEM- or BEM-based fatigue assessment for (non-)proportional loading of load free surfaces is feasible. It will be shown, how the FEM-/BEM-based fatigue assessment will be used and which advantages this new procedure offers. One of the advantages is a process based algebraic sign of the equivalent stress of the MMM-Hypothesis, which matches also the von Mises yield criterion for ductile materials exactly. By using the (modified) Neuber method a non-linear FEM-calculation can be dispensed, without a significant loss of quality in the result but a minor effort in computation. The to presenting damage tolerance analysis is going to exemplify, that it is superior for a complex structure compared to a classical component based evaluation and will allow other statements regarding the prediction of the fatigue life of the structure.
|Commitee:||Liebich, Robert, Grädener, Erik, Mertens, Heinz|
|School:||Technische Universitaet Berlin (Germany)|
|Source:||DAI-C 81/1(E), Dissertation Abstracts International|
|Keywords:||Computation , Validation, Damage tolerance analysis, Complex structures|
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