Process Region Characteristics During Fast Crack Growth
(1991) 11th International Conference of Structural Mechanics in Reactor Technology (SMiRT 11)p.309-314
- Abstract
- The conditions for crack arrest at speeds down to below 0.1 of the Rayleigh-wave speed are examined. The elastic energy release rate is assumed to be balanced by the deformation work in a viscoplastic continua and the energy release rate in a fracture process region. Fractographic show that a small fraction of the surface is created through ductile rupture. Even though the fraction represents only 10- 25 of the surface, it is likely to consume much more energy than the brittle processes. The ductile processes, leading to rupture are assumed to be viscous. A rate dependence is therefore assumed for the process region.
- Abstract (Swedish)
- The fracture process of a laminate is analysed. The laminate is a material used for packaging.It consists of a thin aluminium foil with a polymer coating. In both materials, the fractureprocesses are supposed to be dominantly localized plastic deformation. A Barenblatt regionis supposed to spread ahead of the crack tip. This region is analysed in its cross planeinvoking plane deformation conditions. The fracture process is assumed to be continuousreduction of the cross sectional area in the crack plane until the load carrying capacityvanishes with the vanishing cross sectional area. One case where the interface betweenthe two materials is perfectly bonded and one case with delamination of the interface areexamined. The results are compared... (More)
- The fracture process of a laminate is analysed. The laminate is a material used for packaging.It consists of a thin aluminium foil with a polymer coating. In both materials, the fractureprocesses are supposed to be dominantly localized plastic deformation. A Barenblatt regionis supposed to spread ahead of the crack tip. This region is analysed in its cross planeinvoking plane deformation conditions. The fracture process is assumed to be continuousreduction of the cross sectional area in the crack plane until the load carrying capacityvanishes with the vanishing cross sectional area. One case where the interface betweenthe two materials is perfectly bonded and one case with delamination of the interface areexamined. The results are compared with the properties of the individual layers. At fracturemechanical testing of the laminate, it is observed that the load carrying capacity increasesdramatically as compared with that of the individual layers. When peak load is reachedfor the laminate, strains are fairly small and only the aluminium is expected to carry anysubstantial load because of the low stiffness of the polymer. It is therefore surprising thatthe strength of the laminate is almost twice the strength of the aluminium foil. The reasonseems to be that the constraint introduced across the interface, forces the polymer to absorblarge quantities of energy at small nominal strain. The toughness compares well with theaccumulated toughness of all involved layers. Based on the results, a method is suggestedfor designing ultra tough laminates based on careful selection of material combinations andinterface properties. The method gives a laminate that produces mutlple necking. (Less)
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- author
- Ståhle, Per LU
- publishing date
- 1991
- type
- Chapter in Book/Report/Conference proceeding
- publication status
- published
- subject
- host publication
- Transactions of the 11th International conference on structural mechanics in reactor technology : 18-23 August 1991, Tokyo, Japan. Vol. G1, Fracture mechanics and non-destructive evaluation - 18-23 August 1991, Tokyo, Japan. Vol. G1, Fracture mechanics and non-destructive evaluation
- pages
- 6 pages
- conference name
- 11th International Conference of Structural Mechanics in Reactor Technology (SMiRT 11)<br/>
- conference location
- Tokyo, Japan
- conference dates
- 1991-08-18 - 1991-08-23
- ISBN
- 4-89047-060-3
- language
- English
- LU publication?
- no
- id
- 9f69dd9d-be47-4c65-9297-39c80ccc8b79
- date added to LUP
- 2019-06-26 10:45:21
- date last changed
- 2020-03-13 11:46:31
@inproceedings{9f69dd9d-be47-4c65-9297-39c80ccc8b79,
abstract = {{The conditions for crack arrest at speeds down to below 0.1 of the Rayleigh-wave speed are examined. The elastic energy release rate is assumed to be balanced by the deformation work in a viscoplastic continua and the energy release rate in a fracture process region. Fractographic show that a small fraction of the surface is created through ductile rupture. Even though the fraction represents only 10- 25 of the surface, it is likely to consume much more energy than the brittle processes. The ductile processes, leading to rupture are assumed to be viscous. A rate dependence is therefore assumed for the process region.}},
author = {{Ståhle, Per}},
booktitle = {{Transactions of the 11th International conference on structural mechanics in reactor technology : 18-23 August 1991, Tokyo, Japan. Vol. G1, Fracture mechanics and non-destructive evaluation}},
isbn = {{4-89047-060-3}},
language = {{eng}},
pages = {{309--314}},
title = {{Process Region Characteristics During Fast Crack Growth}},
year = {{1991}},
}