At the end of this page you will find the grasshopper implementation (stresses.gh) of von Mises and Tresca stresses on cylindrical sections. It allows you to control the radius, plate thickness as well as the angle between the middle line and generator. For a straight plate, eg aligned to the border, the angle is zero. The application was developed for grasshopper 0.8.0066, coded in VBScript.
For the implementation in Rhinoscript (stresses.rvb) you can download a Rhino file with sample plates. The code can calculate von Mises and Tresca stresses on both cylindrical and conical sections.