Engineering analysis + design software

User Area > Advice

Using slidelines with higher order elements

The slideline algorithms in LUSAS only use corner nodes in monitoring contact conditions and applying appropriate restraints. For this reason low order elements are recommended in general.

Slidelines may, however, be utilised with higher order elements in which case Modeller will automatically create a constraint equation to ensure that each midside node occurring on a slideline displaces according to the average of the immediately adjacent corner nodes, i.e. forcing the slideline face to act as a linear element.

The disadvantage in using higher order elements is that contact and, particularly, impact can excite element mechanisms. This can be circumvented by specifying fine integration for the element, but at the cost of an increase in solution time as well as the correspondingly "stiffer" solution normally expected with full integration. Moreover, a refined mesh is generally recommended in the area of contact which can result in significant analysis solution times.

The advantage is that classical higher order elements have correspondingly higher order displacement interpolation and can, therefore, simulate greater variations in stress across a single element more accurately, enabling fewer elements to be used. However, for the reason mentioned above, this cannot normally be exploited. It should also be noted that the low order, enhanced strain continuum elements perform as well as the 20-noded at a fraction of the cost. These elements are the default choices in LUSAS Modeller where appropriate. In general they have an "m" at the end of the element name - see the element reference library manual for more information.


innovative | flexible | trusted

LUSAS is a trademark and trading name of Finite Element Analysis Ltd. Copyright 1982 - 2022. Last modified: November 29, 2022 . Privacy policy. 
Any modelling, design and analysis capabilities described are dependent upon the LUSAS software product, version and option in use.