Characterization of negative thermal expansion of shape memory alloys
Characterization of materials is important so as to understand the different properties of the material. This aims to ensure that they can be fully utilized in all of their present and future applications. The present research aims to understand the occurence of the negative thermal expansion phe...
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| Other Authors: | |
| Format: | Final Year Project (FYP) |
| Language: | English |
| Published: |
2009
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| Online Access: | http://hdl.handle.net/10356/16984 |
| _version_ | 1826122630473711616 |
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| author | Wong, Yu Lian. |
| author2 | Liu Yong |
| author_facet | Liu Yong Wong, Yu Lian. |
| author_sort | Wong, Yu Lian. |
| collection | NTU |
| description | Characterization of materials is important so as to understand the different properties of the material. This aims to ensure that they can be fully utilized in all of their present and future applications.
The present research aims to understand the occurence of the negative thermal expansion phenomenon associated with shape memory alloys through experimental means. Two parameters were varied to understand this phenomenon, namely stress applied and initial pre-straining on the specimen.
From the research, it was shown that this phenomenon was only a characteristic of the martensitic phase. It was not observed in the austenitic phase. An increase in the stress applied onto the specimen during thermal cycling has a decreasing effect on the negative thermal expansion. Above a critical stress level, negative thermal expansion effect was not observed. Instead, the material exhibits the positive thermal expansion.
Also, it was shown that the effects of initial pre-straining could be seen on this characteristic. With an increase in initial pre-straining, negative thermal expansion becomes more pronounced until it reaches a critical level. After which, the effects were shown to be slightly reduced.
Lastly, the effects of constraint stress and initial pre-straining was also seen on the transformation temperatures of the specimen.
In conclusion, the effect of constraint stress and initial pre-straining were studied and their effects were shown. This will allow for more specific studies to be targeted in future. |
| first_indexed | 2024-10-01T05:51:17Z |
| format | Final Year Project (FYP) |
| id | ntu-10356/16984 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T05:51:17Z |
| publishDate | 2009 |
| record_format | dspace |
| spelling | ntu-10356/169842023-03-04T19:33:51Z Characterization of negative thermal expansion of shape memory alloys Wong, Yu Lian. Liu Yong School of Mechanical and Aerospace Engineering DRNTU::Engineering::Materials::Metallic materials::Alloys Characterization of materials is important so as to understand the different properties of the material. This aims to ensure that they can be fully utilized in all of their present and future applications. The present research aims to understand the occurence of the negative thermal expansion phenomenon associated with shape memory alloys through experimental means. Two parameters were varied to understand this phenomenon, namely stress applied and initial pre-straining on the specimen. From the research, it was shown that this phenomenon was only a characteristic of the martensitic phase. It was not observed in the austenitic phase. An increase in the stress applied onto the specimen during thermal cycling has a decreasing effect on the negative thermal expansion. Above a critical stress level, negative thermal expansion effect was not observed. Instead, the material exhibits the positive thermal expansion. Also, it was shown that the effects of initial pre-straining could be seen on this characteristic. With an increase in initial pre-straining, negative thermal expansion becomes more pronounced until it reaches a critical level. After which, the effects were shown to be slightly reduced. Lastly, the effects of constraint stress and initial pre-straining was also seen on the transformation temperatures of the specimen. In conclusion, the effect of constraint stress and initial pre-straining were studied and their effects were shown. This will allow for more specific studies to be targeted in future. Bachelor of Engineering (Mechanical Engineering) 2009-05-29T03:03:43Z 2009-05-29T03:03:43Z 2009 2009 Final Year Project (FYP) http://hdl.handle.net/10356/16984 en Nanyang Technological University 94 p. application/pdf |
| spellingShingle | DRNTU::Engineering::Materials::Metallic materials::Alloys Wong, Yu Lian. Characterization of negative thermal expansion of shape memory alloys |
| title | Characterization of negative thermal expansion of shape memory alloys |
| title_full | Characterization of negative thermal expansion of shape memory alloys |
| title_fullStr | Characterization of negative thermal expansion of shape memory alloys |
| title_full_unstemmed | Characterization of negative thermal expansion of shape memory alloys |
| title_short | Characterization of negative thermal expansion of shape memory alloys |
| title_sort | characterization of negative thermal expansion of shape memory alloys |
| topic | DRNTU::Engineering::Materials::Metallic materials::Alloys |
| url | http://hdl.handle.net/10356/16984 |
| work_keys_str_mv | AT wongyulian characterizationofnegativethermalexpansionofshapememoryalloys |