  The yield surface in crystal plasticity can be approached from various
directions during mechanical loading. We consider the competition between
nanoindentation and tensile loading towards plastic yielding. For this purpose,
we develop a two-dimensional discrete dislocation model that is then utilized
to investigate the hardness and pop-in event statistics during nanoindentation
of single crystal under tensile pre-stress. Indentation is performed by using
cylindrical (circular in 2D) indentation with varying radius and under both
displacement and load control. Tensile in-plane stress, varying from zero to
yield strength, is assigned to investigate the effect of pre-stress on hardness
and pop-in statistics. At small indentation depths, the measured hardness is
found to be smaller for larger tensile pre-stress; therefore, we conclude that
nanoindentation can be used to detect plasticity. When indentation depth is
larger, the effect of pre-stress is barely seen. Moreover, we discuss event
statistics and the related effect of pre-stress.
