It is an engineer's judgement. Basically, as long as the structure is slender, your example if it is made of isotropic material qualifies this, you can use beam theory to get pretty good result. However, if higher-frequenies become important, say the 10th bending mode, then you need to use plate theory or even 3D elastodynamics.
It is an engineer's
It is an engineer's judgement. Basically, as long as the structure is slender, your example if it is made of isotropic material qualifies this, you can use beam theory to get pretty good result. However, if higher-frequenies become important, say the 10th bending mode, then you need to use plate theory or even 3D elastodynamics.