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Harvard
Kvarnström, E. och Settergren, M. (2017) Validation of finite element model of a dish-stirling system by performing experimental modal analysis. Göteborg : Chalmers University of Technology (Diploma work - Department of Applied Mechanics, Chalmers University of Technology, Göteborg, Sweden, nr: 2017:15).
BibTeX
@mastersthesis{
Kvarnström2017,
author={Kvarnström, Erik and Settergren, Malin},
title={Validation of finite element model of a dish-stirling system by performing experimental modal analysis},
abstract={The energy consumption in the world is currently higher than ever before and it keeps
rising. There is a fast rising demand for renewable energy sources such as solar power,
and concentrated solar power systems can be a solution to this. However, in order to have
robust systems that can compete with solar photovoltaic technologies, the life span and
operational load effects on the structure need to be ensured. This can be done by using a
validated finite element model. This thesis describes the experimental modal analysis and
finite element analysis of a Dish-Stirling system developed by Cleanergy. The purpose of
the thesis is to perform experiments on the structure to compare simulated results with
actual tests, in order to validate that model in terms of dynamic response.
Testing on the structure was done in two different set-ups, one used for calibration and
the other for validation. The structure was excited using a snap-back method, hanging a
weight from the structure by a shing line and burning the line to excite the structure. The
structure was allowed to oscillate freely and eigenmodes were excited as the vibrations caused
by the excitation were damped out. Data from experiments was processed and system
identification of the response was done in the form of state space models. Eigenfrequencies
and eigenmodes of the state space models were compared to eigenfrequencies and eigenmodes
from the finite element model, which were found by performing modal analysis. Calibration
of different parameters was done, changing one parameter at a time, and the calibrated
data compared to the finite element results. The calibrated parameter which gave the
best correlation between experiments and finite element model was used as input to the
validation.
Due to the complexity of the model, only the first modes were used for the comparison, as
the other modes were too complex, and had frequencies too close to each other to distinguish
between them. Comparing the finite element model with the experiments showed that
the experiments did manage to capture the eigenfrequencies of interest, however, when
comparing the eigenvectors, there were differences in the correlation. Some modes were
captured better than others. Calibration of the model led to a marginally better correlation.
The validation confirmed the calibration, to some extent.
In conclusion, the finite element model corresponds well to the experiments, discrepancies
in the results could be due to faults in experiment methodology, such as measurements were
made too scarcely in the structure. It could also be due to a poorly calibrated finite element
model. In order to further validate the finite element model more extensive experiments
would need to be performed, as well as a more complex calibration procedure.
Keywords: Experimental modal analysis (EMA), Concentrated solar power (CSP), Finite
element analysis (FEA), Modal Analysis, Vibration Testing, Signal processing},
publisher={Institutionen för tillämpad mekanik, Dynamik, Chalmers tekniska högskola},
place={Göteborg},
year={2017},
series={Diploma work - Department of Applied Mechanics, Chalmers University of Technology, Göteborg, Sweden, no: 2017:15},
}
RefWorks
RT Generic
SR Electronic
ID 250496
A1 Kvarnström, Erik
A1 Settergren, Malin
T1 Validation of finite element model of a dish-stirling system by performing experimental modal analysis
YR 2017
AB The energy consumption in the world is currently higher than ever before and it keeps
rising. There is a fast rising demand for renewable energy sources such as solar power,
and concentrated solar power systems can be a solution to this. However, in order to have
robust systems that can compete with solar photovoltaic technologies, the life span and
operational load effects on the structure need to be ensured. This can be done by using a
validated finite element model. This thesis describes the experimental modal analysis and
finite element analysis of a Dish-Stirling system developed by Cleanergy. The purpose of
the thesis is to perform experiments on the structure to compare simulated results with
actual tests, in order to validate that model in terms of dynamic response.
Testing on the structure was done in two different set-ups, one used for calibration and
the other for validation. The structure was excited using a snap-back method, hanging a
weight from the structure by a shing line and burning the line to excite the structure. The
structure was allowed to oscillate freely and eigenmodes were excited as the vibrations caused
by the excitation were damped out. Data from experiments was processed and system
identification of the response was done in the form of state space models. Eigenfrequencies
and eigenmodes of the state space models were compared to eigenfrequencies and eigenmodes
from the finite element model, which were found by performing modal analysis. Calibration
of different parameters was done, changing one parameter at a time, and the calibrated
data compared to the finite element results. The calibrated parameter which gave the
best correlation between experiments and finite element model was used as input to the
validation.
Due to the complexity of the model, only the first modes were used for the comparison, as
the other modes were too complex, and had frequencies too close to each other to distinguish
between them. Comparing the finite element model with the experiments showed that
the experiments did manage to capture the eigenfrequencies of interest, however, when
comparing the eigenvectors, there were differences in the correlation. Some modes were
captured better than others. Calibration of the model led to a marginally better correlation.
The validation confirmed the calibration, to some extent.
In conclusion, the finite element model corresponds well to the experiments, discrepancies
in the results could be due to faults in experiment methodology, such as measurements were
made too scarcely in the structure. It could also be due to a poorly calibrated finite element
model. In order to further validate the finite element model more extensive experiments
would need to be performed, as well as a more complex calibration procedure.
Keywords: Experimental modal analysis (EMA), Concentrated solar power (CSP), Finite
element analysis (FEA), Modal Analysis, Vibration Testing, Signal processing
PB Institutionen för tillämpad mekanik, Dynamik, Chalmers tekniska högskola,PB Institutionen för tillämpad mekanik, Dynamik, Chalmers tekniska högskola,
T3 Diploma work - Department of Applied Mechanics, Chalmers University of Technology, Göteborg, Sweden, no: 2017:15
LA eng
LK http://publications.lib.chalmers.se/records/fulltext/250496/250496.pdf
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