  We consider energy stable summation by parts finite difference methods
(SBP-FD) for the homogeneous and piecewise homogeneous dynamic beam equation
(DBE). Previously the constant coefficient problem has been solved with SBP-FD
together with penalty terms (SBP-SAT) to impose boundary conditions. In this
work we revisit this problem and compare SBP-SAT to the projection method
(SBP-P). We also consider the DBE with discontinuous coefficients and present
novel SBP-SAT, SBP-P and hybrid SBP-SAT-P discretizations for imposing
interface conditions. Numerical experiments show that all methods considered
are similar in terms of accuracy, but that SBP-P can be more computationally
efficient (less restrictive time step requirement for explicit time integration
methods) for both the constant and piecewise constant coefficient problems.
