  We present a unified framework for the calculation of defect energies for
those defects that can be represented as a superposition of isolated
dislocations, and obtain both self and interaction energies of combinations of
grain boundaries and cracks. We recover in special limits several well known
quantities such as the energy of a low-angle tilt boundary, as well as other
lesser known results, including boundary/boundary and crack/boundary
interaction energies. This approach, in combination with simple dimensional
analysis, permits the rapid calculation of defect energetics in the elastic
limit.
