Two robust nonconforming H$^2-$elements for linear strain gradient   elasticity
  We propose two nonconforming finite elements to approximate a boundary value problem arising from strain gradient elasticity, which is a higher-order perturbation of the linearized elastic system. Our elements are H$^2-$nonconforming while H$^1-$conforming. We show both elements converges in the energy norm uniformly with respect to the perturbation parameter. 
Hongliang Li, Pingbing Ming, Zhong-ci Shi
math.NA