Direct modeling approach to improve virtual prototyping and FEM analyses of bicycle frames

Main target of this paper is to analyse the advantages in the use of the Direct Modeling in the Virtual Prototyping processes and in the multiphysics analyses with the help of Reverse Engineering procedures. It is a recent CAD technique that allows the creation and/or modification of models that don’t need parameters and constraints, as on the contrary happens in the Feature Based Modeling. So, it is possible to change the shapes and the dimensions of the original prototypes very easily. Hence, in this paper a methodology devised to acquire and modify a “reconstructed” (non-parametric) model to improve and then to submit it to FEM analysis is presented. Furthermore, it is realized and doesn’t even need the Feature Recognition phase of a typical Reverse Engineering process. In particular, this methodology was applied to a frame of a bicycle used as case study. Its shape was acquired by means of a laser scanner and its virtual prototype was “reconstructed”. In addition, starting from it, two alternative frames were obtained and then easily modified by means of the Direct Modeling techniques. Then, they were submitted to FEM analyses to get different solutions with less weight but similar mechanical performances. Afterwards, the ergonomics of the modified configurations was tested by means of different percentile virtual manikins to plan the physical prototyping of a new improved bicycle.