When we want to incorporate FEA techniques in ouranalysis, we should consider ways to simplify our model. A bike frame has avery small thickness relative to its surface area. Therefore, we can analyzethe geometry using shells. # V% O5 L/ k, _8 h/ kIn SOLIDWORKS, shells are very easy to set up. With thehelp of the Shell Manager,surfaces can be given a thickness, material, offset type, and more within oneconvenient table. 5 s6 [& `5 q2 d" G. N% D: G
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Analysis (computational) times are much lower for shellsthan solid geometry. 7 M5 U1 t- A4 C; u+ W5 E; P1 |7 NFurthermore, laminar edges (coincident surfaces) aretreated as bonded, so there is no need to worry about knitting your surfacesbefore starting your analysis. ! k2 e, D5 T1 ~& [. J3 _! ][attach]365869[/attach]Tapered vs. Non-Tapered Head TubeThere is quite a lot of hype about ‘tapered head tubes’ inthe performance cycling world [where the bottom profile of the head tube tapersout], but how much of a difference does it actually make? To find out, I ran astatic analysis to see if there was any noticeable effect on the frame’sstiffness. . M4 g/ a0 E b) GThe main forces applied to the bike are torsional andlateral forces. Therefore, we can limit our analysis to torsional and lateralstiffness.% E5 K# \2 e5 D2 ?/ J
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These are simplified definitions for a body with onedegree of freedom. This can be applied to our case by analyzing the resultantdeflection in the direction of the applied force as long as one force isapplied at a time for each analysis.1 t- c/ }* m G* \: B+ ?2 e
First, let’s look at the torsional stiffness. In order tocalculate torsional stiffness (for the Head Tube) we can create a resultantplot of the circumferential deflection about the Head Tube Axis (HT AXIS). % ^- }; X) p+ ]/ c% K. h. W- f
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By taking advantage of the extra spaceon the non-drive side, I was able to increase the lateral stiffness of theframe by 11%.
In the next part, I will furtherimprove the performance of the frame design by using CFD (computational fluiddynamics) analysis to optimize for aerodynamic performance.
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Thank you for reading, stay tuned forthe next part!