Hi all, New to the forum. I have a problemI'm tying to solve with regards to an impact load acting against a small peice of a safety catch. The scenario is this... I have a safety catch welded to some box section. This safety catch is made from mild steel and is there to stop an arm (made from 1/2" tube) from swingning out and hitting someone in the face. The arm will therefore hit a section of this safety catch, causing an impact load (see pitcure below for detail). The section that the arm hits is 6mm thick. I've used the formula below (a simple impact load/shock load forumla) to work out the stress such a load will cause. In this forumla V=velocity in m/s, m = mass in kg, E = Young's modulus in GN/m[SUP]2 [/SUP]or GPa, A = area in m[SUP]2 [/SUP], and l = length in m. The arm weighs 1.5Kg, the catch is made from mild steel (E=220 GPa), the area that the arm will hit is 0.00092 m[SUP]2 [/SUP]and the length of that section is 6mm (0.006m). I've chosen velocity as 3 m/s as a benchmark, as this is a relatively slow speed and I cannot imagine the arm breaking this piece of catch at that speed. However, when using all these figures, the stress result is 733.5 MPa. My issue then is that the tensile strength of this mild steel is approx. 400 MPa, meaning that the arm at this velocity, will break the catch...I find that damn near impossible to believe. However, I did think that because of the way that the arm is striking the catch, it may cause shear stress. In this case, is the shear modulus (which is around 80 GPa) what determines whether or not the catch will fail in this situation? Any help would be greatly appreciated.