Reverse adjustment of non-conforming element Qm6
Received:July 22, 2015  Revised:November 12, 2015
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DOI:10.7511/jslx201606020
KeyWord:non-conforming element  patch test  distortion sensitivity  element Q6  element Qm6  4-node quadrilateral element
        
AuthorInstitution
胡圣荣 华南农业大学 工程基础教学与训练中心, 广州
许静静 华南农业大学 工程基础教学与训练中心, 广州
刘新红 华南农业大学 工程基础教学与训练中心, 广州
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Abstract:
      Element Qm6 drops its anti-distortion performance due to especial numerical treatment applied to Q6's matrix [G] of nonconforming items when forcing strong patch test.It is proposed to carry out reverse treatment on element Qm6 to resume and even improve the anti-distortion performance.By analyzing the principle of Qm6,it is pointed out that such principle is essentially to modify adjoint matrix [J*] of Jacobian matrix [J],so in calculating nonconforming items' matrix [G],it is suggested to take [J*] as a variable,do reverse searching along the direction from the corresponding point of Qm6 to that of Q6 for favorable calculation position.Some typical and harsh examples are tested;results show that the reverse treatment is effective,with adjustment factor set to mirror value -1,and further extended to -2,the resulting elements are less sensitive to distortion than the original Q6 and Qm6,especially the value -2 is optimal for elimination of shear locking.Except for weak patch test,the overall performance and accuracy are close to the best of various 4-node quadrilateral elements.With the simplicity of the method and principle,the implementation and generalization to 3D problems have a significant advantage.