FEM Simulation Of Micro-Nano Indentation And Research On Calculation Of Indentation Hardness

With development of MEMS, micro-machining and micro-assembly, it requires higher performance of materials. Hardness can evaluate comprehensive performance of materials, so it is important for strength design and life forecasting of products. Nano-indentation test plays a key role in measuring hardness of materials in micro-nano scale. Experiments in micro-nano scale may be affected by errors from processing and measurement, while simulation can analysis of affect from single factor, helping to understand the variation of indentation hardness in micro-nano scale, and has been widely adopted.The variation of indentation hardness was simulated using ABAQUS, Berkovich, Vickers, conical indenters and different tested materials for micro-nano indentation were modeled, elastic-plastic parameters of materials were set, models were meshed according to characteristic of indentation and mesh deformation, the mesh distortion was controlled by adaptive technology, and step time, loads and boundary conditions were set appropriately.Three methods of indentation hardness calculation were achieved using Matlab , including Oliver-Pharr method, the direct area method and indentation work method, indentation is simulated using ABAQUS with different indenter shapes, different tip radius, indenter tilt, friction and soft film on hard substrate, and the variation of indentation deformation, work and hardness were obtained.Indentation was simulated based on strain gradient theory, compared with classic plastic theory, and the variation of indentation hardness was obtained using Oliver-Pharr method and indentation work method.The result of indentation simulation in micro-nano scale shows that Oliver-Pharr method are affected by indenter tip radius, indenter tilt, friction, base effect and the value of hardness deviates from the theoretical value; indentation work method is not sensitive to factors above, since using energy to calculate hardness.