Interim report on development of progressive failure model for composite bolted joints based on stiffness reduction scheme

The project “A Study of Damage Initiation and Growth in Composite Bolted Joints” is funded under the Basic Research Grants Scheme 2002, jointly administered by Enterprise Ireland and the Irish Research Council for Science, Engineering and Technology. It runs from October 2002 to September 2005. The goal of the project is to develop computational models for prediction of the initiation and growth of damage in composite bolted joints. Two approaches will be investigated. The first will be based on a stiffness reduction scheme. The second will be based on continuum damage mechanics. The two approaches will be compared against experimental data generated within the project and also from a previous EU research project [1], and critically assessed. In this deliverable, an interim report is presented on progress made on developing and applying a stiffness reduction scheme. In Section 2, a description is given of the damage model and its application to a bolted joint tested during the aforementioned EU project [1]. This particular joint was designed to fail in bearing (for a description of composite bolted joint failure modes see deliverable D1.1 of this project [2]). Since bolted joints may also fail in other modes such as net-tension, Section 3 describes the application of the same damage model to a centre-notched tension specimen and results are compared to those found in the literature [3]. Finally, in Section 4, the results of applying the model to an open hole tension specimen to be tested in the present project are described. Section 5 draws conclusions on the findings so far.