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Displacement Amplitude (displacement + amplitude)

Distribution by Scientific Domains
Engineering75%

Selected Abstracts

The effect of surface treatments on the fretting behavior of Ti-6Al-4V alloy

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2008
Matteo Dalmiglio
Abstract Stem modularity in total hip replacement introduces an additional taper joint between Ti-6Al-4V stem components with the potential for fretting corrosion processes. One possible way to reduce the susceptibility of the Ti-6Al-4V/Ti-6Al-4V interface to fretting is the surface modification of the Ti-6Al-4V alloy. Among the tested, industrially available surface treatments, a combination of two deep anodic spark deposition treatments followed by barrel polishing resulted in a four times lower material release with respect to untreated, machined fretting pad surfaces. The fretting release has been quantified by means of radiotracers introduced in the alloy surface by proton irradiation. In a simple sphere on flat geometry, the semispherical fretting pads were pressed against flat, dog-bone shaped Ti-6Al-4V fatigue samples cyclically loaded at 4 Hz. In this way a cyclic displacement amplitude along the surfaces of 20 ,m has been achieved. A further simplification consisted in the use of deionized water as lubricant. A comparison of the radiotracer results with an electrochemical material characterization after selected treatments by potentiostatic tests of modular stems in 0.9% NaCl at 40°C for 10 days confirmed the benefit of deep anodic spark deposition and subsequent barrel polishing for improving the fretting behavior of Ti-6Al-4V. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [source]

Effect of contact configuration on the durability and friction coefficient of pressure-sprayed MoS2 coatings under fretting conditions,

LUBRICATION SCIENCE, Issue 5 2009
D. B. Luo
Abstract Fretting wear is often found at the contact surfaces of a tight assembly where small-amplitude oscillatory movement occurs, which can be the concealed origin of some enormous accidents. Employment of solid lubrication coatings, as one of effective measurements to palliate the fretting damage, has been widely acknowledged. The present work studied the fretting behaviour of a molybdenum disulphide coating on SUS 316 stainless steel substrate by a relatively cheap and easy-to-use process: pressure spraying. Two contact configurations (cylinder-on-flat and ball-on-flat) were used in the tests with different displacement amplitudes (from 5 to 75,µm) and normal loads (from 100 to 400,N for ball-on-flat and from 400 to 1000,N for cylinder-on-flat). The results showed that large displacement amplitude is adverse to friction coefficient and coating lifetime and that under a critical contact pressure, coating endurance is improved contact pressure increases. Contact configuration influences friction coefficient by changing contact area and distribution of contact pressure. One master curve of average dissipated energy per cycle in initial stable stage was obtained for two contact configurations, which can be employed to approximately predict coating lifetime. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Seismic performance of a 3D full-scale high-ductility steel,concrete composite moment-resisting structure,Part I: Design and testing procedure

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 14 2008
A. Braconi
Abstract A multi-level pseudo-dynamic (PSD) seismic test programme was performed on a full-scale three-bay two-storey steel,concrete composite moment-resisting frame built with partially encased composite columns and partial-strength connections. The system was designed to provide strength and ductility for earthquake resistance with energy dissipation located in ductile components of beam-to-column joints including flexural yielding of beam end-plates and shear yielding of the column web panel zone. In addition, the response of the frame depending on the column base yielding was analysed. Firstly, the design of the test structure is presented in the paper, with particular emphasis on the ductile detailing of beam-to-column joints. Details of the construction of the test structure and the test set-up are also given. The paper then provides a description of the non-linear static and dynamic analytical studies that were carried out to preliminary assess the seismic performance of the test structure and establish a comprehensive multi-level PSD seismic test programme. The resulting test protocol included the application of a spectrum-compatible earthquake ground motion scaled to four different peak ground acceleration levels to reproduce an elastic response as well as serviceability, ultimate, and collapse limit state conditions, respectively. Severe damage to the building was finally induced by a cyclic test with stepwise increasing displacement amplitudes. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Effect of contact configuration on the durability and friction coefficient of pressure-sprayed MoS2 coatings under fretting conditions,

LUBRICATION SCIENCE, Issue 5 2009
D. B. Luo
Abstract Fretting wear is often found at the contact surfaces of a tight assembly where small-amplitude oscillatory movement occurs, which can be the concealed origin of some enormous accidents. Employment of solid lubrication coatings, as one of effective measurements to palliate the fretting damage, has been widely acknowledged. The present work studied the fretting behaviour of a molybdenum disulphide coating on SUS 316 stainless steel substrate by a relatively cheap and easy-to-use process: pressure spraying. Two contact configurations (cylinder-on-flat and ball-on-flat) were used in the tests with different displacement amplitudes (from 5 to 75,µm) and normal loads (from 100 to 400,N for ball-on-flat and from 400 to 1000,N for cylinder-on-flat). The results showed that large displacement amplitude is adverse to friction coefficient and coating lifetime and that under a critical contact pressure, coating endurance is improved contact pressure increases. Contact configuration influences friction coefficient by changing contact area and distribution of contact pressure. One master curve of average dissipated energy per cycle in initial stable stage was obtained for two contact configurations, which can be employed to approximately predict coating lifetime. Copyright © 2009 John Wiley & Sons, Ltd. [source]