A stable bilinear element for the Reissner-Mindlin plate model

In this paper, we introduce a new quadrilateral element using isoparametric bilinear basis functions for both components of the rotation vector and the deflection. The element is a stable modification of the MITC4 element. We report on calculations with this new element, the original MITC4 and also the bilinear element, with selective reduced integration. The numerical results are in accordance with the results of the numerical analysis and they show that (i) the method with reduced integration is highly unreliable and cannot be recommended; (ii) the MITC4 performs rather well, but its instability can lead to a decrease in accuracy for the deflection and especially to an inaccurate and oscillating shear force; (iii) the drawbacks of the MITC4 are not present in the modified method.