A modelling-based analysis for fatigue life prediction of SLM printed metal parts due to porosity
Additive manufacturing, also known as rapid prototyping or 30 printing, is an emerging technology which can transfer digital data into physical parts. Selective Laser Melting (SLM) is a powder bed additive manufacturing technique which is used to produce parts . However, due to various defects su...
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| 格式: | Theses and Dissertations |
| 語言: | English |
| 出版: |
2018
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| 主題: | |
| 在線閱讀: | http://hdl.handle.net/10356/73276 |
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| 機構: | Nanyang Technological University |
| 語言: | English |
| 總結: | Additive manufacturing, also known as rapid prototyping or 30 printing, is an emerging
technology which can transfer digital data into physical parts. Selective Laser Melting
(SLM) is a powder bed additive manufacturing technique which is used to produce parts .
However, due to various defects such as pores , probably cracks are formed at different
size defects , leading to fatigue failures under cyclic loading. Usually, the fatigue tests are
conducted to characterise the relation between fatigue life and porosity. The conventional
fatigue analysis is destructive and time-consuming , hence a novel modelling approach is
required for an efficient analysis.
The objective of the present study is to develop a three-dimensional (30) finite-element
model of the parts with pores to study their influence on fatigue life. The twodimensional
(20) finite-element model is also used to analyse the stress concentrations
around the pores and between pores.
The results of the 20 tinite-elernent model show that stress concentration increases when
the distance between circular pores decreases, and increases as the size of pore increases.
Furthermore , the stress concentration around elliptical pore becomes higher than that of
circular one. It is also found that the stress concentration around two adjacent circular
pores reaches the maximum when they are oriented at an angle of 30 degrees. Novel
modelling techniques to present the pores, such as Young ' s modulus reduction and the
element elimination , are integrated into the 30 model of the parts, with pores distribution
as obtained from the actual SLM parts. The fatigue analysis is carried out using
ABAQUS and Fe-Safe software by Stress-based Brown Miller algorithm. From 30
modelling, it is observed that the fatigue life increases as the porosity fraction decreases.
In summary, a technique to model and analyse 30 parts with pores distributed is
developed which is non-destructive and less time-consuming. The fatigue life of those
parts are studied with different porosity fractions which are obtained from SLM process. |
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