Indentation testing, both macro-indentation and micro-indentation, have traditionally been used to determine the hardness and Young’s modulus of materials. In principle, indentation tests are conducted by using an indenter tip with known material properties and, using either displacement control or force control, penetrating the surface of the sample to a desired depth or applied force. The stiffness of the material can be determined by calculating the slope of the unloading phase on the indentation test load vs. displacement curve. Utilizing the stiffness, the reduced Young’s modulus can be derived, and in turn, the value of the specimen elastic modulus can then be calculated. The hardness can be calculated at the maximum penetration (or load) by dividing the maximum force by the cross sectional area of the indenter at this point.
One of the material properties that influences the hardness of a material is its viscoelasticity, and quite often, indentation tests are used to determine the viscoelastic properties of various materials including polymers, soft tissues, and bone. The ElectroForce® 3200 Series II test instrument, with its 1 nanometer resolution, can be utilized with your indenter tips and analysis software to perform microindentation tests on a variety of sample types. Contact us to learn more details.