“FE-Modeling and Optimization of a Bicycle Frame for Road Racing

using Straus7 and iSIGHT FD”

 

Master Thesis by cand. ing. Andreas Kiefmann

 

 

 

 

Sponsored by:

CAEvolution GmbH                      

                            

                                           

 

Problem description:

 

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 concepts.

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 magazine TOUR. 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.

 

Participating parties:

• Institute for Lightweight Structures, Faculty of Mechanical Engineering,

Technical University of Munich (Prof. H. Baier)

• Department of Sports Equipment and Materials, Faculty of Sport Science, Technical University of Munich (Prof. V. Senner)
• Engineous GmbH
• HSH srl., Italy and Strand7/Straus7 Pty Ltd, Australia
• CAEvolution GmbH (www.caevolution.de)