Design Optimization of a Helical Compression Spring

These functions are used in both machine design (SE 410) and engineering design optimization (SE 413) courses at UIUC. The function hcs.m takes as input a design vector that represents a helical compression spring design, as well as optional display and variable selection arguments. It computes, based on the textbook Shigley's Mechanical Engineering Design, the design objective function, as well as manufacturing, stress, and other constraint functions. This design optimization implementation is a simplified version of the spring design element of the suspension co-design problem presented in the following ASME journal article:
http://mechanicaldesign.asmedigitalcollection.asme.org/article.aspx?articleid=1857514
http://systemdesign.illinois.edu/publications/All14b.pdf
The full code for the test problem presented in the journal article is available from:

http://www.mathworks.com/matlabcentral/fileexchange/40504

A video demonstrating an older version of this code is available at:

https://youtu.be/7740qlXuFMk