Field‐consistency and violent stress oscillations in the finite element method

The fact that finite element models can give rise to13; violent stress oscillations has been known for some time. It is also well known that in many problems, there are optimal locations where stresses can be correctly sampled, in spite of the presence of these violent stress fluctuations However, it is less well known that these oscillations arise in a specific class of problems - where there are multiple strain-fields arising from one or more field-variables and where one or more of these strain-fields must be constrained in particular physical13; limits. In this paper, we show that unless the interpolations for these constrained strain-fields are x2018;field-consistentx2019;violent oscillations would set in. These oscillations represent spurious self-equilibrating stress-fields generating spurious energy terms that lead to x2018;lockingx2019;.