Revisiting early works of the aerospace laboratory of Liège. Dual analysis, 60's and 70's

The goal of this presentation is to describe the main scientific contribution of the Aerospace Laboratory of the Liège University (LTAS) during the sixties and seventies. This period was very important for the development of the finite element techniques and the major part of the concepts and the algorithms were defined at that time. The contribution of the LTAS was especially original because it was the only team in the world who was proposing the dual method and included it in a Finite Element code for all the applications : bar, membrane and plates, using for both types of models the same displacement solution algorithm. After the presentation of this method a short description is made about recent improvements proposed by the authors.