I am calculating the strain in a cantilever beam with a point load for a given deflection. The deflection is around .5mm for a beam that is just over 5mm long (width is 3.8mm and height is 0.15mm). I was told for the assumption of small deflections to be valid, deflection should be 2% of the length and in this case it would be 10%. Is this rule of 2% valid? I would assume it would be dependent on the thickness of the beam. Thanks in advance for any input.