Ultra-Thin Film Ultrasonic Characterization

2003 ◽  
Author(s):  
Antanas Daugela ◽  
Vytautas Blechertas ◽  
Oden L. Warren ◽  
Hiroshi Kutomi ◽  
Thomas J. Wyrobek
Keyword(s):  
Excitation Frequency ◽  
Scratch Test ◽  
Statistical Investigation ◽  
Friction Reduction ◽  
Nanometer Scale ◽  
Strain Rates ◽  
Ultrasonic Characterization ◽  
Sample Characterization ◽  
Standing Ultrasonic Wave ◽  
Protective Overcoats

Ultrasonically induced nanoscale fatigue and friction reduction phenomena are researched for nanometer order thick protective overcoats. The newly developed method described here is a synergy of the nanometer scale quantitative nanoindentation/scratch technique and ultrasonic excitation. A standing ultrasonic wave is generated at the sample holder during the quasi-static nanoindentation/scratch test at an excitation frequency of several hundreds of kilohertz. Due to the fact that high strain rates are being generated at the surface of the sample, nanofatigue phenomenon followed by delamination and overcoat chipping can be observed. Statistical investigation of fatigue inducing parameters, such as critical quasistatic load and amplitude of oscillations, leads to a means of comparative sample characterization.

Tribological Testing and Modeling of Elastomeric Materials

2014 ◽  
Vol 604 ◽  
pp. 87-90
Author(s):  
Antti Vaajoki ◽  
Anssi Laukkanen ◽  
Richard Waudby ◽  
Päivi Kivikytö-Reponen ◽  
Kati Valtonen ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Wear Behavior ◽  
Cost Effective ◽  
Scratch Test ◽  
Strain Rates ◽  
Scratch Testing ◽  
Abrasive Particles ◽  
Formidable Challenge ◽  
Elastomeric Materials ◽  
Repeated Impacts

In applications which experience repeated impacts by hard abrasive particles at high or moderate strain rates, elastomers are commonly used. The goal of the current work is to develop a methodology involving scratch testing and modeling which would be simple and cost effective for capturing the failure and wear behavior of elastomeric materials. The high failure strains as well as the extremely good wear resistance of elastomers make this task a formidable challenge. Modeling of a scratch test, however, seems to be promising in this regard.

scholarly journals Experimental Study of High-Frequency Vibration Assisted Micro/Mesoscale Forming of Metallic Materials

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Zhehe Yao ◽  
Gap-Yong Kim ◽  
LeAnn Faidley ◽  
Qingze Zou ◽  
Deqing Mei ◽  
...  
Keyword(s):  
Mass Production ◽  
High Frequency ◽  
Excitation Frequency ◽  
Contact Condition ◽  
Friction Reduction ◽  
Load Reduction ◽  
Metallic Materials ◽  
Reduction Behavior ◽  
High Frequency Vibration ◽  
Metallic Parts

Micro/mesoscale forming is a promising technology for mass production of miniature metallic parts. However, fabrication of micro/mesoscale features leads to challenges due to the friction increase at the interface and tool wear from highly localized stress. In this study, the use of high-frequency vibration for potential application in micro/mesoscale forming has been investigated. A versatile experimental setup based on a magnetostrictive (Terfenol-D) actuator was built. Vibration assisted micro/mesoscale upsetting, pin extrusion and cup extrusion were conducted to understand the effects of workpiece size, excitation frequency, and the contact condition. Results showed a change in load reduction behavior that was dependent on the excitation frequency and the contact condition. The load reduction exhibited in this study can be explained by a combination of stress superposition and friction reduction. It was found that a higher excitation frequency and a less complicated die-specimen interface were more likely to result in a friction reduction by high-frequency vibration.

Processing by Equal-Channel Angular Pressing: Potential for Achieving Superplasticity

1999 ◽  
Vol 601 ◽  
Author(s):  
Minoru Furukawa ◽  
Minoru Nemoto ◽  
Zenji Horita ◽  
Terence G. Langdon
Keyword(s):  
Plastic Strain ◽  
Grain Refinement ◽  
Equal Channel Angular Pressing ◽  
Superplastic Deformation ◽  
Processing Method ◽  
Nanometer Scale ◽  
Strain Rates ◽  
Cross Sectional ◽  
Angular Pressing ◽  
Processing Procedure

AbstractEqual-channel angular (ECA) pressing is a processing procedure whereby a very severe plastic strain is imposed on a sample without any change in the cross-sectional dimensions of the material. This processing method leads to a substantial grain refinement, producing grains which are within the submicrometer or even the nanometer scale. This paper discusses the potential for using this method to prepare materials for superplasticity. The results demonstrate that it is possible to achieve superplastic deformation in selected materials subjected to ECA pressing and, in addition, there is the possibility of extending the superplastic region so that it occurs at very rapid strain rates.

Super Low Friction Property of DLC Lubricated With Ester-Containing Oil: Part 2 — Nanometer-Scale Morphological, Structural and Frictional Properties

2005 ◽  
Author(s):  
Jiping Ye ◽  
Kenichi Ueoka ◽  
Makoto Kano ◽  
Yoshiteru Yasuda ◽  
Yusuke Okamoto ◽  
...  
Keyword(s):  
Tribological Properties ◽  
Friction Reduction ◽  
Engine Oil ◽  
Phase Image ◽  
Nanometer Scale ◽  
Friction Behavior ◽  
Dlc Coating ◽  
Macro Scale ◽  
Alpha Olefin ◽  
Pin On Disc

We have succeeded for the first time anywhere in lowering the friction coefficient of a diamond-like-carbon (DLC) coating to less than 0.01 under boundary lubrication in engine oil [1–3]. This anomalous super-lubrication behavior has been observed for a hydrogen-free DLC-coated (ta-C) disc in an ester-containing oil but not for a hydrogenated DLC (a-C:H) coating. It is thought that some chemical adsorbent may form only on the ta-C sliding surface due to some tribochemical reactions. Our recent studies have suggested that the macro-scale reduction of friction is dependent on nanometer-scale tribological properties [4–6]. The superlow friction behavior seen in a pin-on-disc friction test was taken as the object of this investigation with an eye toward elucidating the mechanism of the anomalous friction reduction. Pin-on-disc tests were conducted by sliding a ta-C/ta-C pair in the presence of poly alpha-olefin based oil containing a modifier additive of glycerol monooleate ester (PAOES1 oil). Nanometer-scale tribological properties were investigated by using atomic force microscopy (AFM), the AFM phase-image technique, and nanoscratch measurements. Attention was focused on the differences in surface roughness, nanostructure and nanofriction coefficient between the sliding and non-sliding areas in an effort to find the origin of the super-lubrication behavior.

scholarly journals Mechanical Properties and Weibull Scaling Laws of Unknown Spider Silks

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2938
Author(s):  
Gabriele Greco ◽  
Nicola M. Pugno
Keyword(s):  
Mechanical Properties ◽  
Size Effects ◽  
Spider Silk ◽  
Scaling Laws ◽  
Statistical Investigation ◽  
Strain Rates ◽  
Cupiennius Salei ◽  
Weibull Parameters ◽  
Spider Silks

Spider silks present extraordinary mechanical properties, which have attracted the attention of material scientists in recent decades. In particular, the strength and the toughness of these protein-based materials outperform the ones of many man-made fibers. Unfortunately, despite the huge interest, there is an absence of statistical investigation on the mechanical properties of spider silks and their related size effects due to the length of the fibers. Moreover, several spider silks have never been mechanically tested. Accordingly, in this work, we measured the mechanical properties and computed the Weibull parameters for different spider silks, some of them unknown in the literature. We also measured the mechanical properties at different strain rates for the dragline of the species Cupiennius salei. For the same species, we measured the strength and Weibull parameters at different fiber lengths. In this way, we obtained the spider silk scaling laws directly and according to Weibull’s prediction. Both length and strain rates affect the mechanical properties of spider silk, as rationalized by Weibull’s statistics.

scholarly journals Experimental Study of High-Frequency Vibration Assisted Micro/Meso-Scale Forming of Metallic Materials

2011 ◽  
Author(s):  
Zhehe Yao ◽  
Gap-Yong Kim ◽  
LeAnn Faidley ◽  
Qingze Zou ◽  
Deqing Mei ◽  
...  
Keyword(s):  
High Frequency ◽  
Excitation Frequency ◽  
Contact Condition ◽  
Friction Reduction ◽  
Load Reduction ◽  
Metallic Materials ◽  
Reduction Behavior ◽  
High Frequency Vibration ◽  
Metallic Parts ◽  
Meso Scale

Micro/meso-scale forming is a promising technology for mass production of miniature metallic parts. However, fabrication of micro/meso-scale features leads to challenges due to the friction increase at the interface and tool wear from highly localized stress. In this study, the use of high-frequency vibration for potential application in the technology of micro/meso-scale forming has been investigated. A versatile experimental setup based on a magnetostrictive (Terfenol-D) actuator was built. Vibration assisted micro/meso-scale upsetting, pin extrusion and cup extrusion were conducted to understand the effects of workpiece size, excitation frequency and the contact condition. Results showed a change in load reduction behavior that was dependent on the excitation frequency and contact condition. The load reduction can be explained by a combination of stress superposition and friction reduction. It was found that a higher excitation frequency and a less complicated die-specimen interface were more likely to result in a friction reduction by high-frequency vibration.

Comparison of Recovery and Recrystallization in Stainless Steel Following Plane-Wave Shock Loading and Explosive Forming

1970 ◽  
Vol 28 ◽  
pp. 428-429 ◽  
Author(s):  
J. A. Korbonski ◽  
L. E. Murr
Keyword(s):  
Stainless Steel ◽  
Shock Loading ◽  
Pressure Pulse ◽  
Shock Pressure ◽  
304 Stainless Steel ◽  
Strain Rates ◽  
Two Dimensional ◽  
Aisi 304 Stainless Steel ◽  
Aisi 304 ◽  
Explosive Forming

Comparison of recovery rates in materials deformed by a unidimensional and two dimensional strains at strain rates in excess of 104 sec.−1 was performed on AISI 304 Stainless Steel. A number of unidirectionally strained foil samples were deformed by shock waves at graduated pressure levels as described by Murr and Grace. The two dimensionally strained foil samples were obtained from radially expanded cylinders by a constant shock pressure pulse and graduated strain as described by Foitz, et al.

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