Material Properties Evaluation of Plastically-Deformed Metal via a Portable Indentation Device 20101833 구성용 20101894 이철용 20111824 김금동 20121850 장호현 20121852 전숙원

Index Concept Development Concept Analysis Job allocation References

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

(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

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

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

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

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

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

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 0.24 for WC Fig. 6 Axisymmetric element without twist

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

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

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

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. 2037 – 2069. Pharr, G. M., Oliver, W. C., Brotzen, F. R., 1992. On the generality of the relationship among contact stiffness, contact area, and elastic modulus during indentation. J. Mater. Res. 7, pp. 613-317. 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.