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“FE-Modeling and Optimization of a Bicycle Frame for
using Straus7 and iSIGHT FD”
Master Thesis by cand. ing. Andreas Kiefmann
Optimizing high-end bicycle frames in terms of weight, stiffness and strength
is the central goal for the development of new designs based on existing
For lightweight structures traditionally materials are chosen like
high-strength aluminum and titanium alloys as well as fiber reinforced plastics.
At the moment for bicycle design numerical methods are rarely used. If used at
all these CAE (=Computer Aided Engineering) tools are very expensive and/or don’t
offer the possibility for optimization.
To resolve and overcome this
problem, an application-oriented combination of the Finite Element package
(Straus7) and Optimization Software (iSIGHT FD) is
going to be developed for offering a useful tool for analysts and designers
within a competitive price/performance relationship.
Methods and Key Objectives:
Subject of the theses are the analysis
and the numerical simulation of different bicycle frames for road racing and
analyzing diverse materials like aluminum and magnesium alloys, fiber
reinforced plastics etc.
One major task of the diploma thesis
is the programming of an interface between the FE package Straus7 within the optimization environment iSIGHT FD using the available Application Programming Interfaces (= API).
The approach will be processed in 4 steps:
- First of all an already commercially
available bicycle frame structure should be simulated and analyzed using
Straus7, “manually” varying parameters like tube shapes, tube diameters
and wall thicknesses. Expected results will be an indication and proposal
of a first lay-out for the dimensioning of the bicycle frame with respect
to the “torsional stiffness” at the headset and the bottom bracket, as
defined by the approved testing description of the German road cycling
The load-cases considered will result from the “maximal loads” experienced
and measured during practice related and relevant runs, as described in
the basic research of Eric Groß, mechanical
engineer, VDI-technological progress report.
- Secondly a “global-local analysis” is
going to be performed. Based on an overall “force-flux-investigation” a local
inspection will be carried out with finer and more detailed FE - meshes,
where loads of the global analysis serve as input values. At this point
mainly “strength criteria” will be considered.
- In a third step selected designs will be
optimized. This optimization step will be carried out using Straus7 as a solver in connection
and in combination with iSIGHT FD.
The optimization will be based on “property optimization”, but for
different designs resulting from CATIA
geometry. For the automated optimization of the bicycle-frame-structure,
both, software components Straus7
and iSIGHT FD need to be interfaced and
connected via the Application Programming Interfaces (API) of Straus7 and the Software
Development Kit (SDK) of iSIGHT FD. Interface parameters need to be
exchanged accordingly performing the simulation / optimization using Straus7. After choosing a fitting
algorithm and defining boundary conditions in iSIGHT FD, an optimization of the analyzed frame structure is done
with respect to the objective functions.
- Finally in a fourth step and completing the study, an
evaluation of the results is arranged in terms of outcomes from usual
methods, plausibility and manufacturing technology. A final documentation will
show the methodical process, the modeling and the software application and
will summarize the results of the designs and the analysis. Perspectives
to further investigations related to different points of the modeling and
the optimization will be highlighted.
for Lightweight Structures, Faculty of Mechanical Engineering,
(Prof. H. Baier)
of Sports Equipment and Materials, Faculty of Sport Science, Technical University
(Prof. V. Senner)
- Engineous GmbH
and Strand7/Straus7 Pty Ltd, Australia
- CAEvolution GmbH (www.caevolution.de)