The World-Wide-Failure-Exercises-I and -II for UD Materials - Valuable attempts to validate Failure Theories on Basis of more or less applicable Test Data

by Prof. Dr. Ralf Cuntze

There was a lack of really validated 2D and 3D strength failure conditions (SFC) for unidirectional (UD) laminas. In the World-Wide-Failure-Exercises WWFE-I (2D stress states) and II (3D stress states), organized by QinetiQ (UK) in the past 20 years, it was extensively attempted to fill this gap. The author participated in both these exercises with a set of 'modal' failure conditions for the brittle behaving, transversely-isotropic UD lamina material composed of endless fibre-reinforced polymers. These conditions base on his so-called Failure Mode Concept (FMC). In the paper the provided, more or less applicable or even not reliable test data sets -provided for the Test Cases (TC) - are discussed with the aim of a better exploitation. There are no further data sets available. Therefore the interested designer must get sufficient knowledge about the quality of the data sets. With a better understanding the designer will be able to perform design verification with a remaining minimum amount of costly test work. To achieve this, the author presents his personal WWFE assessments, provides lessons learnt and draws conclusions.