Efficient fatigue life estimation of structural assemblies based on cyclic test data of individual parts
Sprache des Vortragstitels:
Deutsch
Original Tagungtitel:
12th International Fatigue Congress
Sprache des Tagungstitel:
Englisch
Original Kurzfassung:
In lightweight design a profound fatigue life estimation of structural assemblies is essential in order to ensure that the materials and geometries of involved components are used to its full capacity. Such an estimation is normally based on material fatigue test data of simple specimens and numerous influence factors, which leads to large uncertainties in calculated fatigue life. To avoid such uncertainties our proposed fatigue life estimation method uses test data of specific components and assemblies.
The assemblies considered include two different components, both made of aluminum alloy EN AW 2024. The assembly and therein the components are equally loaded in uniaxial direction. Examples for such assemblies are tie-rods, which are commonly used in automotive or aerospace structures. They are composed of two adapter ends, which are screwed into both ends of a straight tube. The inherent variations in dimensions of all components result in an enormous number of possible assembly combinations, which if a fatigue strength certification is required, leads to an expensive and time consuming testing procedure. Therefore, an efficient analysis method to precisely calculate the fatigue life of new configurations based on test data of individual tubes and adapter ends, as well as finite element simulation data was developed.
The proposed analysis process is shown schematically in Figure 1 and can be divided into three main stages. Firstly, selected fatigue test data with a stress ratio of R=0.01 is utilized to develop accurate and verified finite element models of these individual parts. ...
Sprache der Kurzfassung:
Englisch
Englischer Vortragstitel:
Efficient fatigue life estimation of structural assemblies based on cyclic test data of individual parts
Englischer Tagungstitel:
12th International Fatigue Congress
Englische Kurzfassung:
... Secondly, a statistically appropriate sampling of the design space of different adapter end and tube geometries is used to obtain simulation fatigue data of the various components. These data represent the sampling points for the stochastic meta-models resulting in an analytical description of fatigue data as a function of adapter end and tube geometries. Therefore, these meta-models are able to represent the whole design space of tie-rods within a specific parameter range. Thirdly, the analysis method is finalized by cross-checking the results of the meta-models with test data. Our method is also capable of calculating fatigue life data of assembled tie-rods based on the developed meta-models of single parts. Within this third stage, the calculated fatigue life of assemblies is again compared to the corresponding fatigue test data in order to ensure robustness of our method and further optimization of the meta models and their interaction where required. In general, this method provides a continuous optimization as well as further development of meta-models and finite element models by updating and adding test data. Hence, the design space can be extended to cover a larger range of tie-rod geometries. Consequently, fatigue life predictions of tie-rods with new dimensions, not covered by test data, can be performed using the verified meta-models only.
The proposed powerful characterization of all meaningful tie-rod configurations enables a very fast, accurate and test data driven fatigue life estimation. Moreover, due to its analytical conception, our method is also applicable within an efficient optimization process, helping to identify the strongest but also lightest tie-rod design for a given load environment.
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