Structural Engineering and Mechanics

  • 제55권4호
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  • Pages.857-869
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  • 2015
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  • 1225-4568(pISSN)
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  • 1598-6217(eISSN)
테크노프레스 (Techno-Press)
권호 표지
DOI QR코드

DOI QR Code

Study of dynamic mechanical behavior of aluminum 7075-T6 with respect to diameters and L/D ratios using Split Hopkinson Pressure Bar (SHPB)

  • Kim, Eunhye (Department of Mining Engineering, Colorado School of Mines) ;
  • Changani, Hossein (Department of Mining Engineering, University of Utah)
  • 투고 : 2014.11.29
  • 심사 : 2015.08.04
  • 발행 : 2015.08.25
⟨ 이전 논문 다음 논문 ⟩

초록

The aluminum 7075-T6 is known as an alloy widely used in aircraft structural applications, which does not exhibit strain rate sensitivity during dynamic compressive tests. Despite mechanical importance of the material, there is not enough attention to determine appropriate sample dimensions such as a sample diameter relative to the device bar diameter and sample length to diameter (L/D) ratio for dynamic tests and how these two parameters can change mechanical behaviors of the sample under dynamic loading condition. In this study, various samples which have different diameters of 31.8, 25.4, 15.9, and 9.5 mm and sample L/D ratios of 2.0, 1.5, 1.0, 0.5, and 0.25 were tested using Split Hopkinson Pressure Bar (SHPB), as this testing device is proper to characterize mechanical behaviors of solid materials at high strain rates. The mechanical behavior of this alloy was examined under ${\sim}200-5,500s^{-1}$ dynamic strain rate. Aluminum samples of 2.0, 1.5 and 1.0 of L/D ratios were well fitted into the stress-strain curve, Madison and Green's diagram, regardless of the sample diameters. Also, the 0.5 and 0.25 L/D ratio samples having the diameter of 31.8 and 25.4 mm followed the stress-strain curve. As results, larger samples (31.8 and 25.4 mm) in diameters followed the stress-strain curve regardless of the L/D ratios, whereas the 0.5 and 0.25 L/D ratios of small diameter sample (15.9 and 9.5 mm) did not follow the stress-strain diagram but significantly deviate from the diagram. Our results indicate that the L/D ratio is important determinant in stress-strain responses under the SHPB test when the sample diameter is small relative to the test bar diameter (31.8 mm), but when sample diameter is close to the bar diameter, L/D ratio does not significantly affect the stress-strain responses. This suggests that the areal mismatch (non-contact area of the testing bar) between the sample and the bar can misrepresent mechanical behaviors of the aluminum 7075-T6 at the dynamic loading condition.

키워드

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피인용 문헌

  1. Correlations between the physical and mechanical properties of sandstones with changes of water content and loading rates vol.100, 2017, https://doi.org/10.1016/j.ijrmms.2017.11.005
  2. Effect of water saturation and loading rate on the mechanical properties of Red and Buff Sandstones vol.88, 2016, https://doi.org/10.1016/j.ijrmms.2016.07.005
  3. Numerical simulation of AA7075 under high strain rate with different shape of striker of split Hopkinson Pressure bar vol.26, pp.None, 2015, https://doi.org/10.1016/j.mtcomm.2021.102178
  4. Stress propagation and debonding effects in impedance-graded multi-metallic systems under impact loading vol.12, pp.1, 2015, https://doi.org/10.1177/2041419620917709