Perfectly bonded elastic interface
= Perfectly bonded elastic interface
{title2=$[u]=0,\quad[\sigma]n=0$}
A <perfectly bonded elastic interface> has continuous <displacement field> and continuous <traction>, with the same chosen normal on both sides. For piecewise affine <displacement fields>, the difference of their gradients annihilates every tangential vector, and hence has the form $a\otimes n$. Their <infinitesimal strain tensors> differ by $\operatorname{sym}(a\otimes n)$.