Traditional manual designing of bicycles often relies on prototype building and testing and since structural deficiencies often are not obvious until a prototype fails, several build-and-test iterations are usually required before a satisfactory design is obtained. Also, the final design may be less than optimal because of quick fixes inserted at the last minute. However, by utilizing computer-aided design, better bicycles can be designed at smaller investments of time and money.
The development and utilization of a DI-3000 based (graphics subroutines developed by Precision Visual), user-friendly, self contained computer aided design package for the analysis and design of bicycle frames and forks are presented. The software, written in Fortran 77 and executable on most passive and active graphics devices, creates the necessary analysis input files for the ANSYS finite element program (developed and marketed by Swanson Analysis System Inc.). These pre and post processing files in conjunction with the ANSYS program are used to determine deflections and stress components. The graphics user interface module of the software allows users to enter bicycle geometry, loading and other pertinent data quickly and efficiently. Tubing configuration and specifications are selected from a data base through the use of cursor-controlled menus. The loading menu presents users with seven different types of realistic and self-consistent loading conditions from which to choose. Computer graphics is also used extensively wherever appropriate to enhance user-computer interaction. Contrasting color and text size are used to explain pictorially as well as visually unfamiliar terminology and to clarify vague sign or orientation conventions, thus, leading to more accurate input.
While this package has been designed for instructional purposes, it can also be used by design engineers involved in the design of bicycles to facilitate the creation of ANSYS pre and post processing files.