Elastic/plastic deformation behavior in a continuous ball indentation test

Continuous indentation tests are now commonly used to measure the elastic moduli of materials in accordance with the unloading response of a plastic indentation. However, a previous technique utilizing a Hertzian ball indentation test, applied to the initial loading behavior, is shown to be equally useful provided that sufficient sensitivity is available for the loading curve measurements. Continuous loading measurements for the indentation of lignin are used to demonstrate the possibility of using the loading curve for computing the elastic modulus, and the analysis is carried over to test results on solid and porous aluminum materials. The test results show that the elastic modulus for solid aluminum has a value of 67.8±6.6 GPa, in reasonable agreement with the handbook value. The introduction of few percent porosity reduces the elastic modulus approximately by one-third to 22.6±4.5 GPa.