1. The problem statement, all variables and given/known data I have to create a design to mount a steel (yield=250MPa) weight 100kg and thickness of 15 mm to aluminum plate (Yield = 100MPa) with a tap hole of 15mm in vertical direction with 6 of M6 screws. 2. Relevant equations σ (bearing load) =F/A τ (shear load) = F/A 3. The attempt at a solution Assuming that the force came from the weight of the steel (1000N) I treated this problem as a rivet joint Bearing on bolt = 1000/(6*15*6) = 1.85 MPa Bearing on aluminum plate = 1000/(6*15*6) = 1.85MPa Shear on Bolt (on the thread) = 1000/(6*(phi*6^2)/4) = 0.59 MPa If you look at the calculation, the stress is 100 times smaller than the material properties of the aluminum and steel. This is a very big safety factor. Does that mean I can hang a weight of 100kg with just 1 screw of M1 and still have a safety factor more than 1?? I do not see this make sense. Please advise on how to approach this.