On the penalty behaviour of thin-layer elements

Within the broad class of interface elements in geotechnics, two principle ’schools&s; have been traditional competitors: zero-thickness versus thin-layer elements. With one proponent of either school as co-author, this paper attemps to alleviate common prejudices and to contribute to a unified view of interface finite elements. The key to understanding is the penalty character of the aspect ratios of thin layers, w r hich degenerate to isoparametric interface elements as their thickness approaches zero. Certain locking phenomena observed in thin solids and layer elements are explained. The behaviour of a thin-layer element with a multilaminate constitutive model is illustrated by solving a simple problem. Some results obtained from the analyses of pull-out tests of geotextiles in sand are also briefly presented.