broad coordination;  etc.;  Linear shear stress

The non-coordinated displacement mode can effectively improve the calculation accuracy, but the convergence condition is often not satisfied for any irregular mesh. According to the generalized coordination condition under the linear boundary force, a generalized coordination isoparameter is constructed for any irregular quadrilateral element. The derivation of this element takes into account the linear shear stress condition, so that the displacement coordination condition between the elements is satisfied in the sense of weighted residual number. Furthermore, the corresponding generalized coordination should deform function matrix, and the mode is compact and not prone to singularity. Such parameter pairs can pass the sharding test for any irregular quadrilateral mesh, and degenerate into Q6 when the elements are parallelograms. The example shows that the parameter accuracy of this type is high, and the irregular mesh splitting can maintain good numerical behavior.