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Projects / Programmes source: ARIS

Prediction of loading spectra and their scatter in a R&D process

Research activity

Code Science Field Subfield
2.11.00  Engineering sciences and technologies  Mechanical design   

Code Science Field
T455  Technological sciences  Motors and propulsion systems 
T450  Technological sciences  Metal technology, metallurgy, metal products 
T480  Technological sciences  Technology of other products 
T280  Technological sciences  Road transport technology 
T121  Technological sciences  Signal processing 
Keywords
random load histories, loading spectrum, mixture probability distribution models, operating conditions, non-parametric regression, neural networks, rainflow method
Evaluation (rules)
source: COBISS
Researchers (2)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  00819  PhD Matija Fajdiga  Mechanical design  Head  2004 - 2006 
2.  16334  PhD Jernej Klemenc  Mechanical design  Researcher  2004 - 2006 
Organisations (1)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0782  University of Ljubljana, Faculty of Mechanical Engineering  Ljubljana  1627031 
Abstract
Load states of products are usually described by loading spectra. Loading spectra depend on combinations of different mutually dependent factors of operating conditions. That is why a relationship between the factors of operating conditions and loading spectra is generally non-linear. Due to many influential factors and the non-linearity of the relationship it is almost impossible to assess it by analytical methods. In a preceding doctoral research we tried to empirically model the relationship between the factors of operating conditions and loading spectra by a non-parametric regression method. The nonparametric-regression model was built by representative samples of operating conditions together with corresponding loading spectra and tested by a set of different combinations of operating conditions. It was established that this method enables reliable prediction of loading spectra also for those combinations of operating conditions, for which no measured or simulated load data are available. Despite the promising results obtained in the doctoral research a few drawbacks of this method were noticed: bad extrapolation abilities of the nonparametric regression model and sensitivity of predictions to user-defined parameters. These drawbacks result also in a bad estimation of a scatter of loading spectra. The goal of the post-doctoral project is to develop a new method for predicting loading spectra at given operating conditions on the basis of a limited set of known loading spectra of products. The new method should enable the extrapolation of loading spectra and eliminate the subjective influence of the user as much as possible. This would also result in a better estimation of the scatter of loading spectra. We will try to achieve this goal by applying a special hybrid multi-layer perceptron neural network. Learning and testing of the hybrid neural network will be performed for examples of simulated and measured loading spectra of existing products. The new method will be compared with the results from the doctoral research. The effectiveness of the new method will also be assessed.
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