Mass matrix
================

Obviously, this matrix only intervenes in dynamic problems. The pulley cable element is only used in the *Code_Aster* for quasistatic cable laying problems [§7].

**Note:**

However, [:ref:`bib2 <bib2>`] shows the example of a dynamic problem involving a cable-pulley.

*The mass matrix of the element* :math:`{N}_{1}` :math:`{N}_{2}` :math:`{N}_{3}` *is obtained by assembling the "coherent" mass matrices of the two-node cable elements* :math:`{N}_{3}` :math:`{N}_{1}` *and* :math:`{N}_{3}` :math:`{N}_{2}` [:ref:`bib6 <bib6>`] and adding the pulley's point mass.

*Note that during dynamic analysis, this mass matrix needs to be updated because the lengths* :math:`{l}_{1}` *and* :math:`{l}_{2}` *vary.*