Displacement/pressure mixed interpolation in the method of finite spheres

The displacement-based formulation of the method of nite spheres is observed to exhibit volumetric `lockingʹ when incompressible or nearly incompressible deformations are encountered. In this paper, we present a displacement=pressure mixed formulation as a solution to this problem. We analyse the stability and optimality of the formulation for several discretization schemes using numerical inf{sup tests. Issues concerning computational e ciency are also discussed