Author(s)

K De Proft, L J Sluys & W P De Wilde

Abstract

A combined experimental-numerical study to monotonic and cyclic behaviour of limestone K. De Proft1, L. J. Sluys2 & W. P. De Wilde1 1Department of Mechanics of Materials and Constructions, Vrije Universiteit Brussel, Belgium. 2 Devt University of Technology, The Netherlands. Abstract An experimental test set-up for mode I fracture in limestone (stone of Massangis) is studied. Double-edge notched rectangular specimens are loaded under monotonic and cyclic tension. Both global, i.e. load displacement curve, and local, i.e. crack path, behaviour are studied during the tests. Difficulties arising in the experimental measurement of strain softening behaviour in traction will be discussed. Experimental results are used to validate a numerical model. Within this model, cracks are simulated as displacement discontinuities and are implemented in the finite element context using the partition of unity property of finite element shape functions. 1. Introduction Mode I fracture behaviour of quasi-brittle materials can be studied in different ways. A classical way is to perform uni-axial tensile tests. During these standard tensile tests, both global characteristics, e.g. load displacement curve as well as local characteristics, e.g. the growth of the crack path should be measured. Although the test procedure seems simple, the realization is not straightforward and causes some problems. Apart form the controlling mechanism that should be used in order to create a stable experiment; the results should be interpreted with great care. It was shown in the past ([1], [2]) that the stress and strain state during the experiment are not easy to derive from the

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