Prediction of Elastic-Plastic Behaviour of Structures at Notches
Under the condition of elastic-plastic deformation, aero engine casings experience local stress and strain concentrations along with associated variations in load paths and stiffness. The accurate prediction of such behaviour is clearly necessary for design optimisation, potentially leading to ben...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Mehran University of Engineering and Technology
2012-07-01
|
| Series: | Mehran University Research Journal of Engineering and Technology |
| Subjects: | |
| Online Access: | http://publications.muet.edu.pk/research_papers/pdf/pdf670.pdf |
| Summary: | Under the condition of elastic-plastic deformation, aero engine casings experience local stress and
strain concentrations along with associated variations in load paths and stiffness. The accurate prediction
of such behaviour is clearly necessary for design optimisation, potentially leading to beneficial weight
savings. The present research seeks to tackle the objective of accurate characterisation of elasticplastic
casing behaviour. The objective is to develop approximate techniques for predicting the elasticplastic
behaviour, for both generalised load-displacement responses (i.e. for global response) and notch
stress-strain responses. Accurate prediction of the stress-strain distribution at a notch is difficult and
existing notch prediction techniques can only be used for small strains. This paper seeks to develop novel
techniques for predicting large elastic-plastic notch strain and associated stresses, with application to
aero engine casing notches. The repeated local joints at the spoke-shell casing are of particular interest
as they are the most likely sites for plastic deformation and possibly crack initiation. These local joints
incorporate realistic notch-type features and the load cases cover a range of loading combinations, to
develop insight and understanding of the elastic-plastic behaviour. This work analyse a double edgenotched
flat bar with semicircular notches and a representative case of actual aero engine casing-type
structures in a more simplified form. The investigation was carried out for structures for which stress
and total strain are related by a power law. The equivalent stress at a notch can be estimated, given the
value of n, by a linear interpolation between the stresses for a cases n=1 and n=0. The application of the
notch stress-strain prediction method is illustrated through use of examples of notch components. The
predictions are compared with results obtained using finite element analyses and approximate methods
proposed by Nueber and Glinka. |
|---|---|
| ISSN: | 0254-7821 2413-7219 |