Experimental Techniques

Cover image for Vol. 39 Issue 3

Edited By: Jeffrey Helm

Impact Factor: 0.583

ISI Journal Citation Reports © Ranking: 2013: 20/33 (Materials Science Characterization & Testing); 93/128 (Engineering Mechanical); 114/139 (Mechanics)

Online ISSN: 1747-1567

Most Cited


Read the most cited articles published since 2009


TIPS AND TRICKS FOR CHARACTERIZING SHAPE MEMORY ALLOY WIRE: PART 2—FUNDAMENTAL ISOTHERMAL RESPONSES
Churchill, C. B.; Shaw, J. A.; Iadicola, M. A.

This is the second in a series of articles to introduce phenomena and experimental subtleties that can lead to difficulties in testing shape memory alloy (SMA) wire. Our aims were to acquaint uninitiated engineers with SMA testing and to highlight pitfalls in technique and interpreting test results. Read the entire abstract.

Volume 33, Issue 1, pages 51–62, January/February 2009

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CONTINUOUS STIFFNESS MEASUREMENT DURING INSTRUMENTED INDENTATION TESTING
Hay, J.; Agee, P.; Herbert, E.

Instrumented indentation testing (IIT) is a technique for measuring the mechanical properties of materials. This is the second article in this ET feature series on the topic. The first article was a review of common terminology as well as basic procedures and analyses.1 This article introduces an advanced form of IIT that was developed by Dr. John Pethica and Dr. Warren Oliver about 20 years ago. Read the entire abstract.

Volume 34, Issue 3, pages 86–94, May/June 2010

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INTRODUCTION TO INSTRUMENTED INDENTATION TESTING
Hay, J.

Instrumented indentation testing (IIT) is a technique for measuring the mechanical properties of materials. It is a development of traditional hardness tests such as Brinell, Rockwell, Vickers, and Knoop. IIT is similar to traditional hardness testing in that a hard indenter, usually diamond, is pressed into contact with the test material. However, traditional hardness testing yields only one measure of deformation at one applied force, whereas during an IIT test, force and penetration are measured for the entire time that the indenter is in contact with the material. Read the entire abstract.

Volume 33, Issue 6, pages 66–72, November/December 2009

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FREQUENCY ESTIMATION METHOD FROM DIGITIZED WAVEFORM
Fujii, Y.; Hessling, J. P.

Requirements for estimating the frequency of a single sinusoid with high resolution and high sampling rate have increased in various industrial and research applications. In the field of high-precision mechanical measurement, such as the dynamic calibration of accelerometers1–3 and the dynamic calibration of force transducers,4–6 it is sometimes required to measure the Doppler frequency shift appearing at the interferometer's output port. For measuring the Doppler frequency shift, an electronic frequency counter or a digitizer, that is, a high-speed analog-to-digital converter, is usually used. Read the entire abstract.

Volume 33, Issue 5, pages 64–69, September/October 2009

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A NOVEL FORMULA FOR EFFECTIVE THERMAL CONDUCTIVITY OF VAPOR CHAMBER
Wang, J-C; Wang, R-T

In recent years, power dissipation per chip is projected to reach the range of 100–200 W for high-performance application in electronic devices. The development of cooling technique related to the application of two-phase flow in heat transfer assembly to thermal modules has become mature, and heat pipe-based thermal modules are one of the best choices. Read the entire abstract.

Volume 35, Issue 5, pages 35–40, September/October 2011

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TIPS AND TRICKS FOR CHARACTERIZING SHAPE MEMORY ALLOY WIRE: PART 3-LOCALIZATION AND PROPAGATION PHENOMENA
Churchill, C. B.; Shaw, J. A.; Iadicola, M. A.

This is the third paper in our series to identify unusual phenomena and to provide recommendations for the thermo-mechanical characterization of shape memory alloy (SMA) wire. Part 1 provided some basic background of the martensitic transformations responsible for the shape memory effect and superelasticity1. The characterization of two typical NiTi SMA alloys began with differential scanning calorimetry (DSC) thermograms to measure their respective transformation temperatures, specific heats, and latent heats of transformation. It included an experiment for each alloy showing both shape memory and superelasticity, but in different temperature regimes. Part 2 reviewed the various methods for obtaining a fundamental set of isothermal mechanical responses and provided data on the same two SMA wire alloys over their relevant temperature windows2. In the process, it showed stress-induced transformations, which lead to an introduction of strain localization and propagation of phase transformation fronts. Read the entire abstract.

Volume 33, Issue 5, pages 70–78, September/October 2009

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FULL-SCALE MODAL TESTING OF VAULTED GOTHIC CHURCHES: LESSONS LEARNED
Atamturktur, S.; Pavic, A.; Reynolds, P.; et al.

Gothic-style vaulted churches represent a significant European and North American architectural heritage. Originating in medieval Europe, the Gothic style of construction in unreinforced masonry continued from the 12th through the 16th centuries in Europe and was revived in England and North America in the 19th century. Given their cultural and architectural value, these structures continue to be used for religious services and for tourism even though there is evidence of weakening effects of aging (e.g. creep) and accumulated damage through their life span (e.g. support settlements and prior earthquake damage). As a result of the increasing demand for the condition assessment and rehabilitation of these historic structures, the application of modal testing for condition assessment of large-scale masonry buildings is a growing new area in the field of experimental mechanics. Read the entire abstract.

Volume 33, Issue 4, pages 65–74, July/August 2009

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TIPS AND TRICKS FOR CHARACTERIZING SHAPE MEMORY ALLOY WIRE: PART 4 – THERMO-MECHANICAL COUPLING
Churchill, C. B.; Shaw, J. A.; Iadicola, M. A.

This paper (Part 4) further investigates thermo-mechanical coupling effects, focusing on the superelastic responses of SMA wire. Experiments on the same two NiTi alloys will show how this coupling, as well as the strain localization phenomenon explored in Part 3, combine to form unusual sensitivities to loading rate, thermal conditions, and specimen geometry. Read the entire abstract.

Volume 34, Issue 2, pages 63–80, March/April 2010

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TOMOGRAPHY ANALYSIS OF FIBER DISTRIBUTION AND ORIENTATION IN ULTRA HIGH–PERFORMANCE FIBER-REINFORCED COMPOSITES WITH HIGH-FIBER DOSAGES
Wuest, J.; Denarie, E.; Bruehwiler, E.; et al.

Cementitious materials, such as mortar and concrete, exhibit brittle fracture behavior under tensile forces. Adding metallic fibers to these materials improves the element tensile behavior, but this improvement is a function of the fiber content, distribution, and orientation. In ultra high–performance fiber-reinforced composite (UHPFRC) materials, as in fiber-reinforced composite, the material's strength and hardening and softening behaviors can be significantly undermined if the reinforcing fibers are at a lower content than specified, poorly distributed, or incorrectly oriented.1,2 Thus, knowledge of the fiber orientation and distribution is necessary to correlate and confirm in situ material composition to documented mechanical results. Read the entire abstract.

Volume 33, Issue 5, pages 50–55, September/October 2009

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FINITE ELEMENT SIMULATION OF ISOCLINIC AND ISOCHROMATIC PHASEMAPS FOR USE IN DIGITAL PHOTOELASTICITY
Ashokan, K.; Ramesh, K.

Digital photoelasticity is a whole-field experimental technique which provides the information of principal stress difference (isochromatic, N) and principal stress direction (isoclinic, θ) at every point over the model domain. Phase-shifting techniques that are commonly used for quantitative estimation of photoelastic parameters in digital photoelasticity give only wrapped isoclinic (−π/4 ≤θ≤+π/4) and isochromatic values (0 ≤N≤ 1) in the form of a grey scale image known as a phasemap. Read the entire abstract.

Volume 33, Issue 1, pages 38–44, January/February 2009

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