Agilent Technologies Nano Indenter G200 User Manual page 330

Agilent Nano Indenter G200
User's Guide
A
Continuous Stiffness Measurement
Quick Start Guide A-3
NanoSuite Reference
Required Inputs A-5
Results A-6
Commonly Used Procedures
Setting the Displacement Range for Averaged Properties
Theory A-8
Dynamic Modeling of the Indentation System and Sample
Contact A-8
Calculating Continuous Elastic Modulus and Hardness
Computing Parameters for Polymers
The purpose of this appendix is to provide a brief introduction to the
theory behind the Continuous Stiffness Measurement (CSM) option. In
order to calculate hardness (H) and elastic modulus (E), you must know
the elastic stiffness of the contact, S. Traditionally, S is determined from
the slope of the load-displacement data acquired during unload.
However, such a calculation enables you to determine S (and thus H and
E) only at the maximum penetration depth.
The CSM option enables a continuous measure of S during loading, and
not just at the point of initial unload. This is accomplished by
superimposing a small oscillation on the primary loading signal and
analyzing the resulting response of the system by means of a
frequency-specific amplifier. With a continuous measure of S, you can
obtain hardness and elastic modulus as a continuous function of surface
penetration. The CSM option is available for both the Nano Indenter
G200 and Nano Indenter DCM instruments.
The CSM option is especially useful for evaluating
• Films on substrates, where the mechanical properties change as a
function of surface penetration, and
• Polymers, where both the storage and loss modulus are important.
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