I'm making a robotic structure using hydraulics and pipes, and I need to choose what size pipe and thickness I will be using. I've searched online to the best of my ability but all I got were equations for I-beams. I've taken statics in college so I know how to calculate all the loads in a multi-jointed strucuture. I only need to figure out how to calculate whether or not the structure will hold in the worst-case-scenario and if it will build up fatigue. To clarify, I will be choosing the pipe's diameter, length, thickness, material type (mild steel), and the load, and I need to calculate whether the resulting structure will break or develop fatigue. For now assume the structure is a simple cantilever until I can get a better grasp on the concept. Any help is appreciated.