Residual Strength of Full Scale GRP Laminates with Randomly Distributed Fragment Damages
2013 (English)In: International Conference on Composite Materials 19, 2013Conference paper (Other academic)
A typical scenario of a naval composite ship hull being exposed to air-borne hostile fire can be described as follows; shortly after detonation a scatter of fragments will travel at high speed creating patterns of penetration and perforation damages on the ship hull. Subsequent to these fragment damages a high intensity pressure wave will cause the ship hull panels to deform at an elevated strain rate. Hence, the high intensity pressure wave hits an already damaged structure motivating the study of notched laminates at high rate loading. The design procedure for handling such a complicated loading scenario could be envisaged by the following steps:
We model the geometry of the blast situation, which could be a compartment or a panel surface. One then places the threat at some position where it explodes. By knowledge of the threat one can simulate each fragment having a particular mass, velocity and direction. Each fragment will thus hit the structure and depending on its mass, incident angle and the structure type (material, thickness, etc.) the fragment will penetrate the structure, create some damage or be completely stopped. One thus follow an arbitrary number of fragments and detect which elements they hit in the structure and if they create some damage (e.g. penetration). Such analyses are usually performed using Monte-Carlo simulations. The next step is to create an FE-mesh of the structure. But from the first step one now reduces the properties of the structure, or structural material, by the amount of damage created by the fragments. Some elements will have many holes and thus considerably lower stiffness and strength than the undamaged material. In the final step one performs the blast analysis by applying a transient shock wave with a given momentum and rise time according to the threat assumed. By adopting such a strategy it should not be necessary to model each hole or damage in the structure which would lead to enormous amounts of modelling and computational efforts.
The aim of the present paper is to contribute to the second step in the analysis scheme by finding simple and rational methods to predict the strength reduction of composite laminates with stochastic hole patterns generated by e.g. fragments. This research is based on a methodology developed by Kazemahvazi and Zenkert [1-3] in which more details on section 2-3 can be found. For this paper the phenomenological residual strength model has been further refined and is now used to predict the strength of full scale composite panels with randomly distributed fragment damages.
Place, publisher, year, edition, pages
Composite Science and Engineering
IdentifiersURN: urn:nbn:se:kth:diva-136729OAI: oai:DiVA.org:kth-136729DiVA: diva2:676841
International Conference on Composite Materials 19,July 28 to August 2, 2013 in Montreal, Canada
QC 201312192013-12-072013-12-072013-12-19Bibliographically approved