85.14 Pile up of Dislocation I Mode I Back stress exerted by obstacle on leading dislocation (It is supposed to be a short-range-force ncbdx= tpbdx dx: virtual displacement → BnT§5.14 Pile up of Dislocation ◆ Ⅰ.Model ◆ Ⅱ.Back stress exerted by obstacle on leading dislocation. (It is supposed to be a short-range-force.)     n n b x b x B B  = d = d dx : virtual displacement