1. Material Properties Evaluation of Plastically-Deformed Metal via a Portable Indentation Device
구성용
이철용
김금동
장호현
전숙원

2. Index
Concept Development
Concept Analysis
Job allocation
References

3. 1. Concept Development Material Properties Elastic Properties
Young’s modulus, E
Material Properties
Yield strength, s0
Plastic Properties
Stiffness coefficient, K
Strain-hardening exponent, n

4. (e.g. Vickers, Berkovich, Knoop)
1. Concept Development
Spherical
Shape of Indenter tip
Conical
Others
(e.g. Vickers, Berkovich, Knoop)
Fig. 1 A spherical indenter tip and a conical indenter tip

5. 1. Concept Development Evaluating tool Verification Device FEA
Tensile Test
Evaluating tool
Verification
RSM
Known information
Data transportation
Device
Measuring depth
Measuring load
Etc.

6. Material Properties – E
2. Concept Analysis
Material Properties – E
Young’s modulus ~ the slope of the unloading load-depth curve
n : Poisson’s ratio of specimen (nearly 0.3)
n1 : Poisson’s ratio of indenter
d : actual projected indentation diameter
S : initial unloading slope
E1 : Young’s modulus of indenter
k : correction coefficient (Lee et al., 2005)
Fig. 2 Load – depth curve of indentation test

7. Material Properties – s0, K, and n
2. Concept Analysis
Material Properties – s0, K, and n
Flow stress equation by Swift
Fig. 3 An example of flow stress K
180 ~ 800 n
0.05 ~ 0.50 e0
0.001 ~ 0.004
Data Base of
Load-depth curve
FEA

8. 2. Concept Analysis Indenter tip Spherical Spherical Conical Spherical
Easier in analysis
Less number of indentation
Conical
Spherical
Conical
Others

9. 2. Concept Analysis FEA Cutting a structure into several elements
Describing each element
Reconnecting
Type of each element
3D analysis or 2D analysis using symm.
Size of elements depending on location.
Condition of contact surfaces (friction)
Material properties of indenter
Load conditions
Boundary conditions
Etc.
Fig. 4 Indentation test in reality
Fig. 5 Indentation test described with FEA

10. 2. Concept Analysis - Decision Type of each element : CAX4
What we have done?
- Decision
Type of each element : CAX4
2D analysis using axisymmetry
Friction coefficient : 0.1 – 0.3
Material properties of indenter :
E1 = 1000 GPa, n1 = 0.20 for diamond
550 GPa for WC
Fig. 6 Axisymmetric element without twist

11. 2. Concept Analysis - Decision Bluetooth for data transporting
Device
- Decision
Bluetooth for data transporting
LVDT for measuring depth
Load Cell for measuring load
Actuator motor
Diamond ball indenter or WC ball indenter
Designing an indentation tool via 3D CAD
Fig. 7 Indentation tool skeleton by 3D CAD

12. 2. Concept Analysis specimen Device Load – Depth data
Calculated Material Properties
E : 70 GPa
s0 : 70 MPa
K : 200 MPa
n : 0.20

13. 3. Job allocation
구성용 : Conducting Indentation test simulation reflecting reality
김금동 : Conducting Tensile test simulation reflecting reality & Budget for the project
이철용 : Programming Matlab Code & RSM
장호현 : Programming Matlab code & Designing indentation tool via 3D CAD
전숙원 : Summing up all the information for producing a portable indentation tool

14. 4. References
Abaqus, 2013, Analysis User’s Manual (v6.13), Dassault Systemes.
Lee, H., Lee, J. H., 2005, A numerical approach to spherical indentation techniques for material property evaluation, Journal of the Mechanics and physics of solids 53, pp – 2069.
Pharr, G. M., Oliver, W. C., Brotzen, F. R., On the generality of the relationship among contact stiffness, contact area, and elastic modulus during indentation. J. Mater. Res. 7, pp
Kang, S. K., Kia, Y. C., Kim, K. H., Kim, J. Y., Kwon, D., Extended expanding cavity model for measurement of flow properties using instrumented spherical indentation, International Journal of Plasticity, 2013.