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https://ptsldigital.ukm.my/jspui/handle/123456789/487090Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor.advisor | Prakash Thamburaja, Prof. Dr. | |
| dc.contributor.author | Farzin Mozafari (P84482) | |
| dc.date.accessioned | 2023-10-11T02:28:42Z | - |
| dc.date.available | 2023-10-11T02:28:42Z | - |
| dc.date.issued | 2020-07-13 | |
| dc.identifier.other | ukmvital:122837 | |
| dc.identifier.uri | https://ptsldigital.ukm.my/jspui/handle/123456789/487090 | - |
| dc.description | Most components of machines and structures made out of metals will experience fatigue loading due to applied alternating stresses during their function, and this is the source of failure in the aforementioned components. Although the modelling of fatigue in materials is an age old problem, it is still not a fully understood topic. There is a general consensus that there is currently no physically based universal model available to predict the uniaxial and multiaxial fatigue life response in metals spanning low cycle and high cycle regimes. An even greater challenge exists when the structures experience variable amplitude loading as the most realistic conditions during their service life. Therefore, the main objective of this research work is to develop a constitutive theory that is able to predict the experimental uniaxial and multiaxial fatigue life behaviour of metal based materials spanning the low cycle to high cycle regimes under constant and variable amplitude loading conditions. The key to the development of the model is that the microplastic response before full yield is accounted for by a new approach to inelastic modelling while retaining a rate independent response. Using the principles of thermodynamics, the constitutive theory is formulated in a rate formed, small deformation formulation. An entropy based failure criterion to simulate the fatigue failure of metallic materials is augmented within the constitutive model. Using a robust fully implicit time integration scheme, the developed set of constitutive equations are implemented in the commercially available finite element program ABAQUS/Explicit by writing a user subroutine. With the model suitably calibrated for the aluminium alloy (Al6061-T6) and stainless steel (AISI 304L), the compression stress strain curves for experiments conducted at ambient temperatures are reproduced to good accuracy. It is also shown that the model and its numerical implementation are able to accurately predict the uniaxial fatigue life data for experiments spanning the low cycle to high cycle regimes for the aluminium alloy (Al6061-T6) and stainless steel (AISI 304L) under both stress and strain controlled loading conditions. With the model suitably calibrated for the steel alloy (P355NL1), various uniaxial fatigue tests under different variable amplitude load spectra are simulated numerically and the results compared with experimental data as well as other models for fatigue. From our numerical simulations, we show that our constitutive theory and its finite element implementation are able to describe the experimental data of the steel alloy (P355NL1) under variable amplitude loading to much better accord than other attempts in literature. To further investigate the capabilities of the present constitutive theory, multiaxial fatigue behaviours of the stainless steel (AISI 304L) are predicted. The fatigue predictions show that the constitutive theory and its finite element implementation is able to accurately predict the multiaxial fatigue lifetime response of the stainless steel (AISI 304L) under various strain controlled strain paths.,Ph.D. | |
| dc.language.iso | eng | |
| dc.publisher | UKM, Bangi | |
| dc.relation | Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina | |
| dc.rights | UKM | |
| dc.subject | Universiti Kebangsaan Malaysia -- Dissertations | |
| dc.subject | Dissertations, Academic -- Malaysia | |
| dc.subject | Metals -- Fatigue | |
| dc.subject | Metals | |
| dc.subject | Finite element method | |
| dc.title | An elastic-microplastic-macroplastic based constitutive theory and its finite element implementation : application to prediction of fatigue life in metals | |
| dc.type | Theses | |
| dc.format.pages | 131 | |
| dc.identifier.callno | TA460.M639 2020 3 tesis | |
| dc.identifier.barcode | 005645(2021)(PL) | |
| Appears in Collections: | Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina | |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| ukmvital_122837+SOURCE1+SOURCE1.0.PDF Restricted Access | 14.42 MB | Adobe PDF |  View/Open |
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