A flywheel with a radius R=200 mm is designed to spin up to 8000 rpm. It is proposed to make it out of ductile (nodular) cast iron, but the casting shop can guarantee only that it will have no crack-like flaws greater than 2a=2 mm in length. Use the expression for the maximum stress in a spinning disk in Appendix B7, that for the stress intensity at a small enclosed crack from Appendix B10 and data for cast iron from Appendix A2 and A4 to establish if the flywheel is safe. Take Poisson’s ratio for cast iron to be 0.33.

Data From Appendix A2

Data From Appendix A4 

Data From Appendix B7 

Data From Appendix B10

Table A.2 Density and Price