I started a new job two weeks ago and I've been out of school for twenty years and have not used strength of materials knowlegde since. I had a part fail in the lab and I would like to calculate the force that would have been necessary to cause the shear failure. I have simplified the problem to a 1/2" tall tooth with a cross section area of .125". The material is 303 stainless steel. Can anyone help me with the equation to find this force. I understand that the part failure was caused by repeative stress and not a blunt force but my first step is to find that blunt force value.