Reference problem ===================== Geometry --------- .. image:: images/10000201000002B1000000BA6A48693DAB1E1B1E.png :width: 3.1201in :height: 0.8402in .. _RefImage_10000201000002B1000000BA6A48693DAB1E1B1E.png: The figure above is taken from [:ref:`bib1 `]. Material properties ----------------------- **Beam:** .. csv-table:: "Stiffness", ":math:`{k}_{1}={10}^{7}` and :math:`{k}_{2}=1`" "Masses", ":math:`{m}_{1}={m}_{2}={m}_{3}=1`" Boundary conditions and loads ------------------------------------- The problem is unidirectional according to :math:`x`. The displacement of the first mass is imposed :math:`{u}_{1}=\mathrm{sin}({\omega }_{p}t)` with :math:`{\omega }_{p}=2.`. Initial conditions -------------------- The initial conditions are given by :math:`{u}_{2}(0)={\dot{u}}_{2}(0)={u}_{3}(0)={\dot{u}}_{3}(0)=0`