Surface crack growth in cylindrical hollow specimen subject to tension and torsion
The subject for studies is an aluminium cylindrical hollow specimen with external axial and part circumferential semi-elliptical surface crack undergoing fatigue loads. Both the optical microscope measurements and the crack opening displacement (COD) method are used to monitor and calculate both c...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Gruppo Italiano Frattura
2015-07-01
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| Series: | Fracture and Structural Integrity |
| Subjects: | |
| Online Access: | http://www.gruppofrattura.it/pdf/rivista/numero33/numero_33_art_37.pdf |
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| Summary: | The subject for studies is an aluminium cylindrical hollow specimen with external axial and part
circumferential semi-elliptical surface crack undergoing fatigue loads. Both the optical microscope
measurements and the crack opening displacement (COD) method are used to monitor and calculate both crack
depth and crack length during the tests. The variation of crack growth behaviour is studied under cyclic axial
tension, pure torsion and combined tension+torsion fatigue loading. For the particular surface flaw geometries
considered, the elastic and plastic in-plane and out-of-plane constraint parameters, as well as the governing
parameter for stress fields in the form of In-integral and plastic stress intensity factor, are obtained as a function
of the aspect ratio, dimensionless crack length and crack depth. The combined effect of tension and torsion
loading and initial surface flaw orientation on the crack growth for two type of aluminium alloys is made
explicit. The experimental and numerical results of the present study provided the opportunity to explore the
suggestion that fatigue crack propagation may be governed more strongly by the plastic stress intensity factor
rather than the magnitude of the elastic SIFs alone. One advantage of the plastic SIF is its sensitivity to
combined loading due to accounting for the plastic properties of the material. |
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| ISSN: | 1971-8993 1971-8993 |