Indentation responses of time-dependent films on stiff substrates

2004 ◽  
Vol 19 (8) ◽  
pp. 2487-2497 ◽  
Author(s):  
Michelle L. Oyen ◽  
Robert F. Cook ◽  
John A. Emerson ◽  
Neville R. Moody
Keyword(s):  
Peak Load ◽  
Elastic Response ◽  
Depth Sensing ◽  
Indentation Tests ◽  
Unloading Rate ◽  
Loading And Unloading ◽  
Load Displacement ◽  
Film Substrate ◽  
Single Set ◽  
Substrate Influence

A viscous-elastic-plastic indentation model was extended to a thin-film system, including the effect of stiffening due to a substrate of greater modulus. The system model includes a total of five material parameters: three for the film response (modulus, hardness, and time constant), one for the substrate response (modulus), and one representing the length-scale associated with the film-substrate interface. The substrate influence is incorporated into the elastic response of the film through a depth-weighted elastic modulus (based on a series sum of film and substrate contributions). Constant loading- and unloading-rate depth-sensing indentation tests were performed on polymer films on glass or metal substrates. Evidence of substrate influence was examined by normalization of the load-displacement traces. Comparisons were made between the model and experiments for indentation tests at different peak load levels and with varying degrees of substrate influence. A single set of five parameters was sufficient to characterize and predict the experimental load-displacement data over a large range of peak load levels and corresponding degrees of substrate influence.

scholarly journals Erratum: “Indentation responses of time-dependent films on stiff substrates” [J. Mater. Res. 19, 2487 (2004)]

2004 ◽  
Vol 19 (10) ◽  
pp. 3120-3121
Keyword(s):  
Power Law ◽  
Peak Load ◽  
Indentation Load ◽  
Small Peak ◽  
Peak Loads ◽  
Materials Research ◽  
Indentation Tests ◽  
Unloading Rate ◽  
Loading And Unloading ◽  
Load Displacement

This article appeared in the August 2004 issue of Journal of Materials Research. The following corrections are required.Section II. Experiments p. 2488The third paragraph in the Experiments section should appear as follows:One mechanism to explore changes in the shape of an indentation load-displacement response is to normalize the trace by its peak point. It has been demonstrated that the normalized [h/h(PMAX), P/PMAX] experimental responses for bulk polymers indented at constant loading- and unloading rate with the same rise time (but at different peak load levels) are identical. Figure 1(a) shows raw load-displacement data for indentation tests performed at small peak loads in the thickest polymer film (Epon) in the current study. The peak loads, 1 and 2 mN, were chosen to correspond to depths less than 10% of the film thickness in both cases. The responses normalize to the same shape [Fig. 1(b)]. When the 1-mN normalized response is compared with those from much greater load levels (50 and 500 mN), there are clear changes in the shape of the response, both loading and unloading [Fig. 1(c)]. In particular, the loading response shifts from slightly less than quadratic (power law fit with exponent 1.8) for the 1-mN response, as would be expected for a quadratic material with some creep effect; to a response between quadratic and cubic (power law fit with exponent 2.6) for the 500-mN response. The unloading response is also altered in shape, with a steeper unloading tangent at the larger load.

Simulation of sub-micron indentation tests with spherical and Berkovich indenters

2001 ◽  
Vol 16 (7) ◽  
pp. 2149-2157 ◽  
Author(s):  
A. C. Fischer-Cripps
Keyword(s):  
Experimental Data ◽  
Elastic Modulus ◽  
Material Properties ◽  
Indentation Testing ◽  
Depth Sensing ◽  
Displacement Response ◽  
Analysis Methods ◽  
Detailed Treatment ◽  
Indentation Tests ◽  
Load Displacement

The present work is concerned with the methods of simulation of data obtained from depth-sensing submicron indentation testing. Details of analysis methods for both spherical and Berkovich indenters using multiple or single unload points are presented followed by a detailed treatment of a method for simulating an experimental load–displacement response where the material properties such as elastic modulus and hardness are given as inputs. A comparison between simulated and experimental data is given.

Indentation-induced deformation at ultramicroscopic and macroscopic contacts

2004 ◽  
Vol 19 (1) ◽  
pp. 124-130 ◽  
Author(s):  
Jeremy Thurn ◽  
Robert F. Cook
Keyword(s):  
Plastic Deformation ◽  
Soda Lime ◽  
Soda Lime Glass ◽  
Depth Sensing ◽  
Paraboloid Of Revolution ◽  
Loading And Unloading ◽  
Load Displacement ◽  
Elastic And Plastic Deformation ◽  
Tip Radius ◽  
Unloading Stiffness

Depth-sensing indentation at ultramicroscopic and macroscopic contacts (“nanoindentation” and “macroindentation,” respectively) was performed on four brittle materials (soda-lime glass, alumina titanium carbide, sapphire, and silicon) and the resulting load–displacement traces examined to provide insight to the elastic and plastic deformation scaling with contact size. The load–displacement traces are examined in terms of the unloading stiffness, the energies deposited during loading and recovered on unloading, and the effect of the indenter tip radius on the loading curve. The results of the analyses show that the elastic and plastic deformation during loading and unloading is invariant with the scale of the contact, and the unloading curve is best described by neither a conical tip nor a paraboloid of revolution, but of some compromise.

scholarly journals A new method for hardness determination from depth sensing indentation tests

1996 ◽  
Vol 11 (12) ◽  
pp. 2964-2967 ◽  
Author(s):  
J. Gubicza ◽  
A. Juhász ◽  
J. Lendvai
Keyword(s):  
Contact Pressure ◽  
Elastic Material ◽  
Depth Sensing ◽  
Hardness Number ◽  
Indentation Tests ◽  
Semiempirical Formula ◽  
Loading And Unloading ◽  
The Mean ◽  
Limiting Case

A new semiempirical formula is developed for the hardness determination of the materials from depth sensing indentation tests. The indentation works measured both during loading and unloading periods are used in the evaluation. The values of the Meyer hardness calculated in this way agree well with those obtained by conventional optical observation, where this latter is possible. While the new hardness formula characterizes well the behavior of the conventional hardness number even for the ideally elastic material, the mean contact pressure generally used in hardness determination differs significantly from the conventional hardness number when the ideally elastic limiting case is being approached.

Depth-sensing indentation response of ordered silica foam

2004 ◽  
Vol 19 (1) ◽  
pp. 260-271 ◽  
Author(s):  
Yvete Toivola ◽  
Andreas Stein ◽  
Robert F. Cook
Keyword(s):  
Cell Walls ◽  
Colloidal Crystal ◽  
Pore Collapse ◽  
Depth Sensing ◽  
Load Range ◽  
Peak Displacement ◽  
Load Displacement ◽  
Colloidal Crystal Templating ◽  
Film Substrate ◽  
Microscopy Images

Depth-sensing indentation was applied to three-dimensionally ordered silica foams of two different pore diameters—500 nm and 850 nm—formed by colloidal crystal templating. The contact responses of indentations with Berkovich and hemispherical indentation tips are presented over a load range of 1 mN to 100 mN. Scanning electron microscopy images of residual indentation impressions showed homogeneous deformation for small loads in which the peak displacement was shallow relative to the film–substrate interface. The characteristics of the load–displacement responses changed from periodic discontinuities, associated with cell wall fracture and pore collapse, to smooth and increased stiffness, as a result of densification due to the accumulation of material under the indentation tip and proximity (and contact) of the substrate. Load–displacement responses were translated into pressure–volume space, in which the average pressure during indentation is a measure of the crushing pressure of the cell walls.

Depth-sensing indentation at macroscopic dimensions

2002 ◽  
Vol 17 (10) ◽  
pp. 2679-2690 ◽  
Author(s):  
Jeremy Thurn ◽  
Dylan J. Morris ◽  
Robert F. Cook
Keyword(s):  
Contact Area ◽  
Peak Load ◽  
Ceramic Materials ◽  
Depth Sensing ◽  
Macroscopic Scale ◽  
Load Displacement ◽  
Tip Radius ◽  
Hardness Values ◽  
Two Parameter

A macroscopic-scale depth-sensing indentation apparatus with the ability to be mounted on an inverted microscope for in situ observation of contact events was calibrated using the Oliver and Pharr [J. Mater. Res. 7, 1564 (1992)] procedure with a two-parameter area function. The calibrated Vickers tip was used to determine the projected contact area at peak load and the modulus and hardness of a variety of non-metallic materials through deconvolution of the measured load-displacement traces. The predicted contact area was found to be identical to the measured area of residual contact impressions. Furthermore, for transparent ceramic materials the projected contact area during loading was found to be the same as the area measured from the diagonal of post-indentation residual contact impressions. The modulus and hardness values deconvoluted from the load–displacement traces were compared with independent measurements. The effects of sample clamping, column compliance, and tip radius on the load–displacement data and inferred materials properties were also examined. It is suggested that the simplicity of instrumentation and operation, combined with the ability to observe indentations optically, even in situ, makes macroscopic-scale depth-sensing indentation ideal for fundamental studies of contact mechanics.

Study on behaviour of geometrically scaled glass reinforced epoxy tubes subjected to non-coincident quasi static-indentation

2018 ◽  
Vol 9 (5) ◽  
pp. 675-692
Author(s):  
Fahad Almaskari ◽  
Farrukh Hafeez
Keyword(s):  
Peak Load ◽  
Repeated Loading ◽  
Damage Growth ◽  
Content Type ◽  
Starting Point ◽  
Static Indentation ◽  
Indentation Tests ◽  
Loading And Unloading ◽  
Force Displacement ◽  
Practical Implications

Purpose The purpose of this paper is to study the behaviour of glass reinforced epoxy tubes subjected to repeated indentation loads at two non-coincident indentations 180° apart. Design/methodology/approach Four geometrically scaled specimens ranging from 100 to 400 mm diameter were used in repeated indentation tests. Force, displacement and damage growth were recorded for loading and unloading until the indenter returned to its original starting point. Findings Similar scaled trends were observed between the non-coincidental loadings. Unlike reported response form coincidental loadings, the responses from non-coincidental loadings yield lower values for bending stiffness and peak load. Research limitations/implications The differences in behaviour of the specimen between non-coincident loadings were attributed to reductions in fracture toughness and circumferential modulus. Practical implications Distant non-interacting damage and delamination around the circumference does reduce the structural performance. Originality/value Behaviour of composite tubes under different loading conditions, for example low speed impact or quasi static indentation, is widely studied, however little attention has been given to the repeated loading incidents.

scholarly journals Viscoelastic effects during unloading in depth-sensing indentation

2002 ◽  
Vol 17 (10) ◽  
pp. 2604-2610 ◽  
Author(s):  
A. H. W. Ngan ◽  
B. Tang
Keyword(s):  
Linear Viscoelasticity ◽  
Room Temperature ◽  
Peak Load ◽  
Displacement Curve ◽  
Linear Variation ◽  
Depth Sensing ◽  
Viscosity Parameter ◽  
Viscoelastic Effects ◽  
Unloading Rate ◽  
Rate Plot

With polypropylene as a prototype viscoelastic material at room temperature, it was found that a “nose” may appear in the unloading segment of the load–displacement curve during nanoindentation when the holding time at peak load is short and/or the unloading rate is small, and when the peak load is high enough. The load at which the nose appears was also found to decrease linearly with decreasing unloading rate. A linear viscoelasticity analysis was performed to interpret this effect. The analysis predicts a linear variation between the nose load and the unloading rate, and the slope of such a linear variation is also shown to be proportional to the viscosity parameter of the material. Thus, by measuring the slope of the nose-load versus unloading rate plot at a given temperature, the viscosity parameter of the specimen can be found. This is a new way of measuring the viscosity parameter of a material in addition to the existing method of force modulation and noting the frequency response of the displacement.

Influence of Substrate Hardness on the Response of W–C–Co-coated Samples to Depth-sensing Indentation

2000 ◽  
Vol 15 (8) ◽  
pp. 1766-1772 ◽  
Author(s):  
J. V. Fernandes ◽  
A. C. Trindade ◽  
L. F. Menezes ◽  
A. Cavaleiro
Keyword(s):  
Indentation Depth ◽  
Critical Value ◽  
The Other ◽  
Differential Analysis ◽  
Depth Sensing ◽  
Indentation Tests ◽  
Influence Of Substrate ◽  
Film Substrate ◽  
Substrate Hardness ◽  
Measured Hardness

Depth-sensing indentation tests were used to determine the hardness of amorphous W–C–Co coatings deposited on different steel and copper substrates. The hardness of the film, Hf, was chosen to be always greater than the hardness of the substrate Hs and within the range Hf/Hs = 2 to 18.5. The influence of the ratio Hf/Hs on the ratio (t/hD)C between the film thickness t and the critical value of the indentation depth (hD)C, for which the substrate starts to deform plastically, was studied. Two independent methods were used to determine (hD)C values. One utilized the differential analysis of the loading part of the indentation curve, and the other was based on the plot of (Hc – Hs)/(Hf − Hs) versus t/(hD), Hc being the measured hardness of the film/substrate composite at a given indentation depth (hD). A good correlation between both methods was found.

Numerical Derivative Analysis of Load-Displacement Curves in Depth-Sensing Indentation

2003 ◽  
Vol 791 ◽  
Author(s):  
Tom Juliano ◽  
Vladislav Domnich ◽  
Tom Buchheit ◽  
Yury Gogotsi
Keyword(s):  
Thin Film ◽  
Single Crystal Silicon ◽  
Indentation Load ◽  
Fused Silica ◽  
Depth Sensing ◽  
Crystal Silicon ◽  
Derivative Analysis ◽  
Loading And Unloading ◽  
Load Displacement ◽  
Carbide Derived Carbon

ABSTRACTThe use of load-displacement derivative behavior and power-law curve fitting is applied to find the location of events for a number of different materials during depth-sensing indentation. Load-displacement curves for Berkovich indentations on fused silica, fullerene thin film on sapphire, CdTe thin film on silicon, single crystal silicon, carbide derived carbon, and a polymethylmethacrylate/hydroxyapatite (PMMA/HA) particle composite are examined. The analysis is applied to quantify the location of different events that occur during material loading and unloading.

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