Method for measuring elastic properties
AssigneeThe University of Hong Kong
InventorsGang Feng, Alfonso Hing Wan Ngan
Life of this patent
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Abstract
This invention relates to a method for measuring elastic modulus of a sample object. This invention also relates to a method for correcting creep effects in the modulus measurement. The error due to creep in the apparent contact compliance is equal to the ratio of the indenter displacement rate at the end of the load hold to the unloading rate. Determination of this error term and deduction of it from the measured contact compliance can be easily done at a low cost by modifying the data analysis software in any commercial depth-sensing indentation system.
Claims19
A method for measuring the contact stiffness during an unloading process in depth-sensing indentation, comprising:
- measuring the indenter displacement drift rate hh just prior to the unload process;
- measuring the apparent contact stiffness Su at the onset of the unloading process;
- and
- obtaining the contact stiffness S based on one or more of the indenter displacement drift rate hh, the apparent contact stiffness Su, and P;
- wherein P is the imposed unloading rate at the onset of the unload process.
The method for obtaining a correction term for correcting for the effects of creep, comprising determining a correction term based in part on one or more of the indenter displacement drift rate hh, the apparent contact stiffness Su, and the imposed unloading rate P wherein:
- the indenter displacement drift rate hh, is measured prior to the unloading process;
- the apparent contact stiffness Su is measured at the onset of the unloading process;
- and
- the imposed unloading rate P is measured at the onset of the unloading process.
A method for correcting for the effects of creep in the measurement of a material property during an unloading process in the depth-sensing indentation, comprising:
- measuring the indenter displacement drift rate hh prior to the unloading process;
- measuring the apparent contact stiffness Su at the onset of the unloading process;
- measuring the imposed unloading rate P at the onset of the unload process;
- obtaining a correction term based on one or more of the indenter displacement drift rate hh, the apparent contact stiffness Su, and P;
- and
- determining a corrected material property using the correction term.
Dependencies are inferred from the claim text.