Effect of contact stiffness and machine calibration in nano-indentation testing

ABSTRACTWe have evaluated the hardness and elastic properties of thin films by using a simple procedure to calibrate the tip shape effect of the nano-indentation data. For the simplification, a truncated-shape approximation and linear fit are used to estimate the tip-shape and contact stiffness, respectively, substituting for polynomial area-function and power-law fit. The parameters used in the correction were determined by a fused silica and a single crystal silicon (100) surface. Different film/substrate systems are designed in order to assess these fitted parameters used in the correction. The transition behavior observed from the film to the substrate is well coincide with the other film thickness results, where the indentation depth above 50nm.

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Nano-indentation testing of new and fractured nickel-titanium endodontic instruments

International Endodontic Journal ◽

10.1111/j.1365-2591.2011.01997.x ◽

2011 ◽

Vol 45 (5) ◽

pp. 462-468 ◽

Cited By ~ 11

Author(s):

A. Jamleh ◽

A. Sadr ◽

N. Nomura ◽

Y. Yahata ◽

A. Ebihara ◽

...

Keyword(s):

Nickel Titanium ◽

Indentation Testing ◽

Nano Indentation

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Spherical Indentation Creep Following Ramp Loading

MRS Proceedings ◽

10.1557/proc-841-r5.9 ◽

2004 ◽

Vol 841 ◽

Cited By ~ 3

Author(s):

Michelle L. Oyen

Keyword(s):

Contact Stiffness ◽

Peak Load ◽

Polymeric Materials ◽

Spherical Indenter ◽

Material Behavior ◽

Spherical Indentation ◽

Indentation Creep ◽

Indentation Testing ◽

Depth Sensing ◽

Linear Viscoelastic Material

ABSTRACTDepth-sensing indentation testing is a common way to characterize the mechanical behavior of stiff, time-independent materials but presents both experimental and analytical challenges for compliant, time-dependent materials. Many of these experimental challenges can be overcome by using a spherical indenter tip with a radius substantially larger than the indentation depth, thus restricting deformation to viscoelastic (and not plastic) modes in glassy polymers and permitting large loads and contact stiffness to be generated in compliant elastomers. Elastic-viscoelastic correspondence was used to generate spherical indenter solutions for a number of indentation testing protocols including creep following loading at a constant rate and a multiple ramp-and-hold protocol to measure creep response at several loads (and depths) within the same test. The ramp-creep solution was recast as a modification to a step-load creep solution with a finite loading rate correction factor that is a dimensionless function of the ratio of experimental ramp time to the material time constant. Creep tests were performed with different loading rates and different peak load levels on glassy and rubbery polymeric materials. Experimental data are fit to the spherical indentation solutions to obtain elastic modulus and time-constants, and good agreement is found between the results and known modulus values. Emphasis is given to the use of multiple experiments (or multiple levels within a single experiment) to test the a priori assumption of linear viscoelastic material behavior used in the modeling.

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