Material Property Identification and Sensitivity Analysis Using Micro-Indentation

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Long Ge ◽  
Nam H. Kim ◽  
Gerald R. Bourne ◽  
W. Gregory Sawyer
Keyword(s):  
Mechanical Properties ◽  
Sensitivity Analysis ◽  
Material Properties ◽  
Numerical Technique ◽  
Response Surfaces ◽  
Small Scale ◽  
Test Statistics ◽  
Indentation Experiment ◽  
The Difference ◽  
Micro Indentation

Mechanical properties of materials in small-scale applications, such as thin coatings, are often different from those of bulk materials due to the difference in the manufacturing process. Indentation has been a convenient tool to study the mechanical properties in such applications. In this paper, a numerical technique is proposed that can identify the mechanical properties using optimization and evaluate the robustness of identified material properties using sensitivity analysis. First, two response surfaces are constructed for loading and unloading curves from the indentation experiment of a gold film on the silicon substrate. Unessential coefficients of the response surface are then removed based on the test statistics. Unlike the traditional methods of identification, the tip geometry of the indenter is included because its uncertainty significantly affects the results. In order to validate the accuracy and stability of the method, the sensitivity of the identified material properties with respect to each coefficient is analyzed. It turns out that the plastic hardening parameter is the most sensitive to the experimental data. In addition, all material parameters are sensitive to the coefficients of higher-order bases. However, their effects are diminished because the magnitudes of these coefficients are small.

Material Property Identification and Sensitivity Analysis Using Indentation and FEM

2006 ◽  
Author(s):  
Long Ge ◽  
Nam Ho Kim ◽  
Gerald R. Bourne ◽  
W. Gregory Sawyer
Keyword(s):  
Mechanical Properties ◽  
Numerical Technique ◽  
Response Surfaces ◽  
Small Scale ◽  
Test Statistics ◽  
Element Analysis ◽  
Property Identification ◽  
Indentation Experiment ◽  
Loading And Unloading ◽  
The Difference

Mechanical properties of materials in small-scale applications, such as thin coatings, are often different from those of bulk materials due to the difference in the manufacturing process. Indentation has been a convenient tool to study the mechanical properties in such applications. In this paper, a numerical technique is proposed that can identify the mechanical properties by minimizing the difference between the results from indentation experiments and those from finite element analysis. First, two response surfaces are constructed for loading and unloading curves from the indentation experiment of a gold film on the silicon substrate. Unessential coefficients of the response surface are then removed based on the test statistics. Different from the traditional methods of identification, the tip geometry of the indenter is included because its uncertainty significantly affects the results. In order to validate the accuracy and stability of the method, the sensitivity of the identified material properties with respect to each coefficient is analyzed.

Remarks on Crack-Bridging Concepts

1992 ◽  
Vol 45 (8) ◽  
pp. 355-366 ◽  
Author(s):  
G. Bao ◽  
Z. Suo
Keyword(s):  
Mechanical Properties ◽  
Large Scale ◽  
Ceramic Matrix Composites ◽  
Notch Sensitivity ◽  
Small Scale ◽  
Matrix Composites ◽  
Crack Bridging ◽  
Scale Bridging ◽  
Hole Radius ◽  
The Difference

The article draws upon recent work by us and our colleagues on metal and ceramic matrix composites for high temperature engines. The central theme here is to deduce mechanical properties, such as toughness, strength and notch-ductility, from bridging laws that characterize inelastic processes associated with fracture. A particular set of normalization is introduced to present the design charts, segregating the roles played by the shape, and the scale, of a bridging law. A single material length, δ0E/σ0, emerges, where δ0 is the limiting-separation, σ0 the bridging-strength, and E the Young’s modulus of the solid. It is the huge variation of this length—from a few nanometers for atomic bond, to a meter for cross-over fibers—that underlies the richness in material behaviors. Under small-scale bridging conditions, δ0E/σ0 is the only basic length scale in the mechanics problem and represents, with a pre-factor about 0.4, the bridging zone size. A catalog of small-scale bridging solutions is compiled for idealized bridging laws. Large-scale bridging introduces a dimensionless group, a/(δ0E/σ0), where a is a length characterizing the component (e.g., hole radius). The group plays a major role in all phenomena associated with bridging, and provides a focus of discussion in this article. For example, it quantifies the bridging scale when a is the unbridged crack length, and notch-sensitivity when a is hole radius. The difference and the connection between Irwin’s fracture mechanics and crack bridging concepts are discussed. It is demonstrated that fracture toughness and resistance curve are meaningful only when small-scale bridging conditions prevail, and therefore of limited use in design with composites. Many other mechanical properties of composites, such as strength and notch-sensitivity, can be simulated by invoking large-scale bridging concepts.

Irradiation of Polyamide Measured by Micro-Indentation Test

2015 ◽  
Vol 1120-1121 ◽  
pp. 1179-1182
Author(s):  
Martin Ovsik ◽  
David Manas ◽  
Miroslav Manas ◽  
Michal Stanek ◽  
Adam Skrobak ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surface Layer ◽  
Material Properties ◽  
Indentation Test ◽  
Polymer Chains ◽  
Cross Linking ◽  
Indentation Hardness ◽  
Chemical Bonds ◽  
Depth Sensing ◽  
Micro Indentation

Cross-linking is a process in which polymer chains are associated through chemical bonds. This research paper deals with the possible utilization of irradiated polyamide. Influence of the intensity of irradiation on micro-indentation hardness was investigated. Material properties created by β – radiation are measured by micro-indentation test using the DSI method (Depth Sensing Indentation). Hardness increased with increasing dose of irradiation at everything samples; however results of micro-indentation test shows increasing in micro-mechanical properties of surface layer. The highest values of micro-mechanical properties were reached radiation dose of 99 kGy, when the micro-mechanical values increased by about 18%.

scholarly journals Localized Heat Treatment to Improve the Formability of Steel Pipes for Hydraulic Applications: Process Design and Mechanical Characterization

2021 ◽  
Author(s):  
Luigi Bruno ◽  
Santo Canto ◽  
Luciano Luciani
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Test ◽  
Material Properties ◽  
Mechanical Characterization ◽  
Indentation Test ◽  
Image Correlation ◽  
Full Field ◽  
Spatial Gradients ◽  
Micro Indentation

Abstract In the present work, authors have demonstrated how a localized induction heat treatment can be advantageously applied, controlled and mechanically characterized on a specific part – i.e. on steel hose fittings for hydraulic applications. More specifically, the study shows how this specific type of heat treatment facilitates the acquisition of significant localization effects on mechanical properties, and how such a treatment could act as a powerful tool for material optimization in diverse applications. The instrumented micro-indentation test was adopted as the investigation method for mechanical characterization and, due to the reduced amount of material required for the test, has the double advantage of retrieving potential spatial gradients of the mechanical properties without causing permanent damage to the entirety of analyzed parts. The measurement of both the Vickers hardness and plastic work required to make the indentation that would be necessary to quantify the strength and ductility capability of the parts’ material. In addition, a customized tensile test, based on the strains measurement obtained through an optical full-field method – i.e. Digital Image Correlation (DIC) – was developed with the aim of identifying and quantifying the correlation between the material properties attainable through a conventional tensile test and those measured by the instrumented micro-indentation test. Finally, it was demonstrated that the proposed customized tensile test, due to the localized heat treatment, is capable of retrieving potential spatial gradients of material properties.

scholarly journals Thermostructural Analysis of Plate-Type Heat Exchanger Prototypes Considering Weld Properties

2012 ◽  
Vol 2012 ◽  
pp. 1-12
Author(s):  
Kee-nam Song ◽  
Sung-deok Hong
Keyword(s):  
Mechanical Properties ◽  
Heat Exchanger ◽  
Material Properties ◽  
Structural Integrity ◽  
Weld Zone ◽  
Parent Material ◽  
Small Scale ◽  
Hastelloy X ◽  
Weld Properties ◽  
Plate Type

The mechanical properties in a weld zone are different from those in the parent material owing to their different microstructures and residual weld stresses. Welded plate-type heat exchanger prototypes made of Hastelloy-X alloy were manufactured, and performance tests on the prototypes were performed in a small-scale nitrogen gas loop at the Korea Atomic Energy Research Institute. Owing to a lack of mechanical properties in the weld zone, previous research on the strength analyses of the prototypes was performed using the parent material properties. In this study, based on the mechanical properties of Hastelloy-X alloy obtained using an instrumented indentation technique, strength analyses considering the mechanical properties in the weld zone were performed, and the analysis results were compared with previous research. As a result of the comparison, a thermostructural analysis considering the weld material properties is needed to understand the structural behavior and evaluate the structural integrity of the prototype more reliably.

Impact of Small-Scale Reeling Simulation on Mechanical Properties on Line Pipe Steel

2014 ◽  
Author(s):  
Karl Christoph Meiwes ◽  
Marion Erdelen-Peppler ◽  
Holger Brauer
Keyword(s):  
Mechanical Properties ◽  
Thermal Aging ◽  
Test Procedure ◽  
Testing Procedure ◽  
Small Scale ◽  
Pipe Material ◽  
Compression Tests ◽  
Line Pipe ◽  
The Difference ◽  
Load Conditions

Reel-laying is a fast and cost effective method to install pipelines since the time consuming operations of welding and inspection are conducted onshore. During reel-laying repeated plastic strain is introduced into a pipeline which may affect strength and ductility of the line pipe material. Based on the experience, it has been shown that the small-scale reeling test procedure according to DNV-OS-F101 [1] is a good way to inspect the mechanical properties for the reel-laying process. Coupons from pipes are loaded in tension and compression tests and aged if required. Specimens for mechanical testing are machined from these coupons and tested according to the corresponding standards. This paper demonstrates current efforts to demonstrate the usability of cold-formed HFI pipes from Salzgitter Mannesmann Line Pipe GmbH (MLP) for the reel-laying process. In a first step the results of the pre-strained materials are compared in extensive material tests with the undeformed incoming materials. The effect of thermal aging from the coating process on the reeling behavior is then examined, in relation to the background of thermal aging. In discussing the difference between compression and tension zone of the reeled pipe, the influence according to the load conditions is analyzed by the material property tests. This paper demonstrates current efforts of the availability for use of cold-formed HFI pipes for the real-laying process. In addition, the report notes the difference and the effects of the material properties to testing according to the strain-based or stress-based load conditions. In discussing the influence of the tempered conditions of the mechanical properties, therefore two different pipe conditions are investigated by the small scale-reeling (SSR) testing procedure. In summary the results of the pre-strain materials are comparable with the unformed incoming materials.

scholarly journals Multiscale optimisation of resonant frequencies for lattice-based additive manufactured structures

2020 ◽  
Author(s):  
Morgan Nightingale ◽  
Robert Hewson ◽  
Matthew Santer
Keyword(s):  
Material Properties ◽  
Large Scale ◽  
Response Surfaces ◽  
Mode Shapes ◽  
Small Scale ◽  
Multiscale Approach ◽  
Modal Assurance Criterion ◽  
Resonant Frequencies ◽  
Frequency Constraints ◽  
The Impact

AbstractThis paper introduces a novel methodology for the optimisation of resonant frequencies in three-dimensional lattice structures. The method uses a multiscale approach in which the homogenised material properties of the lattice unit cell are defined by the spatially varying lattice parameters. Material properties derived from precomputed simulations of the small scale lattice are projected onto response surfaces, thereby describing the large-scale metamaterial properties as polynomial functions of the small-scale parameters. Resonant frequencies and mode shapes are obtained through the eigenvalue analysis of the large-scale finite element model which provides the basis for deriving the frequency sensitivities. Frequency tailoring is achieved by imposing constraints on the resonant frequency for a compliance minimisation optimisation. A sorting method based on the Modal Assurance Criterion allows for specific mode shapes to be optimised whilst simultaneously reducing the impact of localised modes on the optimisation. Three cases of frequency constraints are investigated and compared with an unconstrained optimisation to demonstrate the algorithms applicability. The results show that the optimisation is capable of handling strict frequency constraints and with the use of the modal tracking can even alter the original ordering of the resonant mode shapes. Frequency tailoring allows for improved functionality of compliance-minimised aerospace components by avoiding resonant frequencies and hence dynamic stresses.

A hybrid method for determining material properties from instrumented micro-indentation experiments

1994 ◽  
Vol 9 (5) ◽  
pp. 1314-1321 ◽  
Author(s):  
Y-M. Chen ◽  
A.W. Ruff ◽  
J.W. Dally
Keyword(s):  
Penetration Depth ◽  
Material Properties ◽  
Ofhc Copper ◽  
Material Constants ◽  
Computation Process ◽  
Indentation Experiment ◽  
Micrometer Scale ◽  
The Impact ◽  
The Relationship ◽  
Micro Indentation

The impact code EPIC was employed to study the relationship between the applied force and the penetration depth in a micrometer-scale indentation experiment with oxygen free high conductivity (OFHC) copper. EPIC is an elastic-plastic finite element code that uses a Lagrangian formulation and triangular mesh, which can accommodate large deformation without the need to remesh during the computation process. By fitting the force-penetration curves for a triangular indenter with second degree polynomials, it was demonstrated that the fit changed with two material constants in the constitutive equation. A systematic procedure for determining the material constants is described that is based on matching either the slope or the curvature of the force penetration depth curves from numerical simulation and experiments. It is concluded that material constants can be determined from indentation data obtained using pyramidal or spherical indenters as well as a flat-ended indenter.

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