RFun: a Grasshopper plug-in for analyzing Relaxed Funicularity of shells

The concept of Relaxed Funicularity (also known as R-Funicularity or RF) extends the traditional notion of funicularity for continuous shells by considering the effects of "small" bending moments through the evaluation of generalized eccentricity. This paper presents RFun, a Grasshopper plug-in designed to analyze the Relaxed Funicularity of any continuous shell structure. Developed in CPython using the RhinoCommon API, the custom component library enables the computation of generalized eccentricity values, the definition of eccentricity ellipses, and the visualization of eccentricity directions. A dedicated component was also implemented to generate various types of streamlines, including eccentricity lines, by adopting a neighbor-seeding logic. The main contribution of this work is to provide an accessible and user-friendly tool for studying and analyzing the principles of Relaxed Funicularity. By leveraging Grasshopper's parametric interface, RFun allows users with even basic scripting proficiency to explore and investigate the concept of Relaxed Funicularity, fostering a broader understanding and application of its principles.