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@PHDTHESIS{VillegasUlloa:860510,
author = {Villegas Ulloa, Claudio Nabil},
othercontributors = {Corves, Burkhard and Hernandez Frias, Alfonso},
title = {{S}ynthesis of linkages considering dynamic aspects},
school = {Rheinisch-Westfälische Technische Hochschule Aachen},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2022-11439},
pages = {1 Online-Ressource : Illustrationen, Diagramme},
year = {2022},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University 2023; Dissertation, Rheinisch-Westfälische
Technische Hochschule Aachen, 2022},
abstract = {Nowadays, there is a constant demand of mechanisms that
operate at higher speeds and with good accuracy without
compromising its reliability. This requires that the
mechanism possess good dynamic behavior. The dynamics are
traditionally considered at the end of the mechanism design
process. If any problem is detected in this stage, it is
necessary to go back in the design process for
recalculation, leading to undesirable loops. This is
particularly challenging for linkages that operate at high
speeds because of the inherent nonlinearity of the system.
The nonlinear motion of the system generates periodic forces
with multiple harmonics that can excite one of the
eigenfrequencies of the system. If the forces are low and
the eigenfrequencies of the system are far enough from the
harmonic components of high amplitude, the dynamic response
of the system can be of low amplitude. However, these facts
are not commonly analyzed in the early stages of the design
process.Methods to include the dynamic considerations in the
early stages of the mechanism design process are presented
in this dissertation. They are applied to function-generator
linkages, namely four-bar linkages and Watt II linkages. The
input link of the mechanisms rotates at constant rate while
the output link swings. The latter link moves a body of
constant inertia.Different approaches are studied starting
with a parametric study of the effects that a swinging body
has on the reaction forces on the joints of a four-bar
linkage. Then, four bar linkages are synthesized for the
case of moving an external body of extremely high inertia,
and then, for a more general case. After that, six-bar
linkages are synthesized with two heuristic methods, the
genetic algorithm and the non-dominated sorting genetic
algorithm modified (NSGA II). These approaches consider the
force on the joints as a first indicator of good dynamic
behavior and constrain the first eigenfrequency, among other
variables. The resulting mechanism are compared against an
elastic multibody simulation. Comparative results show a
good correlation between resulting mechanisms and
simulations, with predictable forces, relatively low
vibration of the links and low deviation of the flexible
output link with respect to a rigid model.},
cin = {411910},
ddc = {620},
cid = {$I:(DE-82)411910_20180101$},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2022-11439},
url = {https://publications.rwth-aachen.de/record/860510},
}
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