活動與演講
115學年材料所-第五週 專題研討課程 演講公告 (115年10月8日)
發佈日期 :
2026-10-06
最後更新日期 :
2026-10-06
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全部消息,活動與演講
2026.10.08
115學年上學期專題討論公告
題目:
Advanced Small-Scale Mechanical Testing for Material Research
演講者: 李伯軒
現職: 國立中山大學機械與機電工程學系助理教授
時間: 115年10月08日(四) 下午15:20~17:10
地點: 成功大學成功校區三系館 鋼構區(3F)共同教室A1302演講廳
演講摘要:
Small-scale mechanical tests are versatile techniques for measuring mechanical properties when the materials are of limited volume, or the features of interest are of micro or nanometre size. However, the small-scale mechanical properties often exhibit an intriguing size effect. It is well-known that nanoindentation and micro-pillar compression tests can exhibit significant higher hardness and flow stress, showing a smaller-is-stronger behaviour. This can be explained by a combination of strain-rate gradient theory and dislocation starvation/nucleation process, showing that dislocation behaviour at small-scale is responsible for the mechanical size effect. The more recent small-scale fracture tests also exhibited an interesting smaller-is-tougher trend, showing that even in the most brittle material, e.g. Si, can exhibit plastic flow at temperatures well below the brittle-to-ductile transition temperatures (BDTT). However, in some semi-brittle metallics, e.g. W, the BDTT remain similar with macrosopic values, showing that failure ramain mostly intergranular. Therefore, it is important to compare small-scale mechanical properties with macroscopic values to validate the tests. I will demonstrate the usage of high-temperature micro-fracture nanoindentation strain-rate jump tests to measure both fracture and plastic properties, and provide macrocopic values of the same materials for validation.
115學年上學期專題討論公告
題目:
Advanced Small-Scale Mechanical Testing for Material Research
演講者: 李伯軒
現職: 國立中山大學機械與機電工程學系助理教授
時間: 115年10月08日(四) 下午15:20~17:10
地點: 成功大學成功校區三系館 鋼構區(3F)共同教室A1302演講廳
演講摘要:
Small-scale mechanical tests are versatile techniques for measuring mechanical properties when the materials are of limited volume, or the features of interest are of micro or nanometre size. However, the small-scale mechanical properties often exhibit an intriguing size effect. It is well-known that nanoindentation and micro-pillar compression tests can exhibit significant higher hardness and flow stress, showing a smaller-is-stronger behaviour. This can be explained by a combination of strain-rate gradient theory and dislocation starvation/nucleation process, showing that dislocation behaviour at small-scale is responsible for the mechanical size effect. The more recent small-scale fracture tests also exhibited an interesting smaller-is-tougher trend, showing that even in the most brittle material, e.g. Si, can exhibit plastic flow at temperatures well below the brittle-to-ductile transition temperatures (BDTT). However, in some semi-brittle metallics, e.g. W, the BDTT remain similar with macrosopic values, showing that failure ramain mostly intergranular. Therefore, it is important to compare small-scale mechanical properties with macroscopic values to validate the tests. I will demonstrate the usage of high-temperature micro-fracture nanoindentation strain-rate jump tests to measure both fracture and plastic properties, and provide macrocopic values of the same materials for validation.