Effect of Applied and Residual Stresses on the Analysis of Mechanical Properties by Means of Instrumented Indentation Techniques

Various methods have been proposed in recent years for the determination of mechanical properties of a material by using instrumented indentation testing. These load and depth sensing indentation techniques imply the measurement of a characteristic load-indentation depth curve by the aid of which numerous materials properties can be extracted. On the other hand in many publications the effect of applied or residual stresses on the results of hardness readings is investigated. Methods are proposed to estimate applied or residual stresses by means of instrumented indentation testing. Based on this obvious inconsistency between these procedures on the use of information of instrumented hardness testing the influence of residual stresses as well as applied stresses on continuous microhardness readings is systematically investigated for steel samples. Experimental investigations were supplemented by finite element simulations of ball indentation tests on equi-biaxially prestressed materials states. These simulations show that the registered force-indentation depth curves as well as the geometry of the indentations are affected by loading and residual stresses in a characteristic way. For hardness values changes of up to 35% are determined with reference to the unstressed initial state.

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Comparison of mechanical properties of thermally modified wood at growth ring and cell wall level by means of instrumented indentation tests

Holzforschung ◽

10.1515/hf.2009.085 ◽

2009 ◽

Vol 63 (4) ◽

Cited By ~ 21

Author(s):

Stefanie Stanzl-Tschegg ◽

Wilfried Beikircher ◽

Dieter Loidl

Keyword(s):

Mechanical Properties ◽

Cell Wall ◽

Thermal Treatment ◽

Mechanical Performance ◽

Growth Ring ◽

Beech Wood ◽

Thermal Modification ◽

Wood Structure ◽

Instrumented Indentation ◽

Indentation Tests

Abstract Thermal modification is a well established method to improve the dimensional stability and the durability for outdoor use of wood. Unfortunately, these improvements are usually accompanied with a deterioration of mechanical performance (e.g., reduced strength or higher brittleness). In contrast, our investigations of the hardness properties in the longitudinal direction of beech wood revealed a significant improvement with thermal modification. Furthermore, we applied instrumented indentation tests on different hierarchical levels of wood structure (growth ring and cell wall level) to gain closer insights on the mechanisms of thermal treatment of wood on mechanical properties. This approach provides a variety of mechanical data (e.g., elastic parameters, hardness parameters, and viscoelastic properties) from one single experiment. Investigations on the influence of thermal treatment on the mechanical properties of beech revealed similar trends on the growth ring as well as the on the cell wall level of the wood structure.

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Techniques for Determining Mechanical Properties of Power-Law Materials by Instrumented Indentation Tests

Engineering Plasticity and Its Applications - Key Engineering Materials ◽

10.4028/0-87849-433-2.555 ◽

2007 ◽

pp. 555-562

Author(s):

J. Lin ◽

J. Luo ◽

T.A. Dean

Keyword(s):

Mechanical Properties ◽

Power Law ◽

Instrumented Indentation ◽

Indentation Tests

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

Journal of Materials Research ◽

10.1557/jmr.2001.0293 ◽

2001 ◽

Vol 16 (7) ◽

pp. 2149-2157 ◽

Cited By ~ 6

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.

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Indentation for investigation of strain rate effect on mechanical properties in structural steel weld zone

Journal of Science and Technology in Civil Engineering (STCE) - NUCE ◽

10.31814/stce.nuce2019-13(3)-10 ◽

2019 ◽

Vol 13 (3) ◽

pp. 104-112

Author(s):

Pham Thai Hoan ◽

Nguyen Ngoc Vinh ◽

Nguyen Thi Thanh Tung

Keyword(s):

Mechanical Properties ◽

Yield Strength ◽

Strain Rate ◽

Structural Steel ◽

Weld Zone ◽

Strain Rate Effect ◽

Rate Effect ◽

Steel Weld ◽

Instrumented Indentation ◽

Indentation Tests

In this study, instrumented indentation testing was conducted at room temperature for the investigation of the effect of strain rate on the hardness and yield strength in the weld zone of a commonly used structural steel, SM520. A number of indentation tests were undertaken at a number of strain rate values from 0.02 s-1 to 0.2 s-1 in the weld metal (WM), heat-affected zone (HAZ), and base metal (BM) regions of the weld zone. The mechanical properties including yield strength (σy) and hardness (H) in WM, HAZ, and BM were then computed from the applied load-penetration depth curves using a proposed method. As the result, the effects of strain rate indentation on yield strength and hardness in all regions of the weld zone were evaluated. The results displayed that hardness and yield strength in the weld zone’s components are influenced on the strain rate, where both hardness and yield strength decrease with the decreasing strain rate. Keywords: indentation; mechanical properties; strain rate effect; structural steel; weld zone.

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Application of a portable indentation rig with Rockwell indenter to determine mechanical properties and residual stresses on an aluminum plate

The Journal of Strain Analysis for Engineering Design ◽

10.1177/0309324720921289 ◽

2020 ◽

Vol 55 (7-8) ◽

pp. 246-257

Author(s):

Saba Salmani Ghanbari ◽

Amir-Hossein Mahmoudi

Keyword(s):

Mechanical Properties ◽

Residual Stresses ◽

Structural Integrity ◽

Indentation Load ◽

Instrumented Indentation ◽

Unknown Parameters ◽

Plastic Properties ◽

Wide Range ◽

Portable Apparatus ◽

Non Destructive

Measuring residual stresses is still a dilemma in many engineering applications. It is even more crucial when the industrial requirements demand for a non-destructive technique in order to avoid compromising the structural integrity of the engineering components. Furthermore, estimating the mechanical properties of the materials, especially when the components are aged, is of importance. Instrumented indentation has gained much interest in recent years. There are many studies in the literature which are focused on measuring residual stresses or mechanical properties using instrumented indentation. Since in many cases there is no possibility of transferring large samples or those under service, for possible measurements, having a portable rig can be very useful. Furthermore, indentation procedure is a low-cost non-destructive method with high accuracy which is able to measure the plastic properties of material as well as its residual stresses on which the designing and construction of the portable apparatus were based. The instrumented indentation testing details were followed according to the ASTM E2546-15 standard practice. In this research, a wide range of simulations were performed on a group of aluminum alloys in order to estimate the equi-biaxial residual stresses by analyzing the indentation load–displacement curves which were obtained from the experimental outcomes. Then neural networks were employed to estimate the unknown parameters. The performance accuracy of the designed portable apparatus and the acceptable precision of the introduced method were then verified with experimental tests performed on Al 2024-T351.

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Technological support of physical-mechanical properties surface layer in parts at electro-mechanical finishing

Science intensive technologies in mechanical engineering ◽

10.30987/2223-4608-2020-12-22-30 ◽

2020 ◽

Vol 2020 (12) ◽

pp. 22-30

Author(s):

Vladimir Fedorov ◽

Anatoliy Suslov ◽

Maksim Nagorkin

Keyword(s):

Mechanical Properties ◽

Surface Layer ◽

Residual Stresses ◽

Work Hardening ◽

Mechanical Treatment ◽

Cold Work ◽

Alternating Current ◽

Experimental Investigations ◽

Processing Factor ◽

Technological Support

The problems in the parameter formation of cold work hardening and residual stresses of a surface layer in steel 45 parts at electro-mechanical finishing with the use of alternating current are considered. There are presented proce-dures for experimental investigations and their standard results as tables and diagrams. The analysis of processing factor impact upon characteristics under investigation is carried out. The simulators of their formation in the course of processing which can be used in practice are obtained. With the use of the method of simulation there is defined para-metric reliability of the technological system of electro-mechanical treatment on the characteristics of physical-mechanical properties of a surface.

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The Influence of Spraying Parameters on Stresses and Mechanical Properties of HVOF-Sprayed Co-Cr-W-C Coatings

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.606.171 ◽

2014 ◽

Vol 606 ◽

pp. 171-174 ◽

Cited By ~ 3

Author(s):

Jiří Matějíček ◽

Šárka Houdková ◽

Olga Bláhová ◽

Zdenek Pala

Keyword(s):

Mechanical Properties ◽

Residual Stresses ◽

Particle Temperature ◽

Instrumented Indentation ◽

Stellite 6 ◽

Young’S Moduli ◽

Particle Characteristics ◽

Spraying Parameters ◽

The Relationship

Stellite 6 Co-Cr-W-C coatings were sprayed by HVOF while systematically varying the spraying parameters, namely the equivalent ratio and combustion pressure. During spraying, the in-flight particle temperature and velocity were measured. Deposition, thermal and residual stresses were determined by in-situ curvature monitoring of the sprayed samples. Young's moduli and hardness of the coatings were determined by instrumented indentation. The relationship between spraying parameters, in-flight particle characteristics and mechanical properties is discussed.

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