Dear all, I have written a code for dynamic analysis of a mechanical structure. My primary purpose is to find natural frequencies of the structure. When I test my code for a cantilever bar whose natural frequencies are known analytically, I found a big difference between the the first frequency obtained from my code and the analytical one . More importantly, the results depend on mesh size more than I expect. The difference is more for bars with lower thickness. I guess something is wrong with the stiffness matrix but I can't find problem. Please see the attached figure to compare results for different mesh size. Is the difference due to discretization error? Someone earlier advised me to do something to avoid shearlocking and hourgalssing. I haven't done anything about that. In the model seen in figure, could the error be because shearlocking and/or hourgalssing ? Note: I have used lumped mass matrix which is diagonal. The diagonal elements are all equal to 1/8 of the element mass. Thanks.