Negative,zero and positive stiffness in extended Eshelby plates

Structures under loading can show positive and negative stiffness (during buckling) with zero stiffness just being one point of transition. Material structures with extended zero stiffness regimes have also been reported. Using the example of an extended Eshelby plate with a positive and negative edge dislocation, we show the existence of finite regimes of positive, zero and negative stiffness in a single system. Given that stable states/configurations of negative stiffness cannot exist in an isolated system; we show the existence of metastable states of negative stiffness along with unstable states of positive stiffness. The system also exhibits one point of unstable equilibrium.