Stress intensity factor of aircraft attachment lug with cracked holes
This project deals with the determination of stress intensity factor numerically and experimentally in order to predict the crack propagation in the attachment straight lug. The specimen was made of Aluminium alloy A17075-T651 with two symmetric quarter comer elliptical cracks placed diametricall...
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| Format: | Theses and Dissertations |
| Language: | English |
| Published: |
2016
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| Subjects: | |
| Online Access: | http://hdl.handle.net/10356/68667 |
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| Institution: | Nanyang Technological University |
| Language: | English |
| Summary: | This project deals with the determination of stress intensity factor
numerically and experimentally in order to predict the crack propagation in the
attachment straight lug. The specimen was made of Aluminium alloy A17075-T651
with two symmetric quarter comer elliptical cracks placed diametrically opposite to
each other around a hole. An initial elliptical part through crack was fabricated in
the specimen so that the crack propagation can be predicted with the application of
load. Three crack configurations were used in this work so that the propagation of
crack can be compared for three different cases. Initially, the specimen was
subjected to tensile loading where the load was applied for different crack
configurations until it fails. This gives the ultimate tensile load with which the
experiment was proceeded. A specific percentage of breaking load was used to
carry out the fatigue tests with the help of marker load history. This kind of
loading leaves distinct markings on the specimen surface during fracture. The
striation lines correspond to the periodic amplitude load sequence. These marks
were clearly captured using portable digital microscope. The pictures taken were
edited using Photoshop to increase its contrast and brightness settings for an even
clearer view. These marks were analysed and the crack propagation was measured.
It is then analysed and data processing were carried out to obtain the results. A two
dimensional through-the-thickness finite element analysis was carried out for
straight lug with single crack and two symmetric cracks on the edge of a hole using
ANSYS WORXBENCH 15. From the results obtained, the effect of geometry
factor on the crack propagation was studied. |
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