The Experts below are selected from a list of 201 Experts worldwide ranked by ideXlab platform

Raymond M Measures - One of the best experts on this subject based on the ideXlab platform.

  • Thermal Apparent-Strain sensitivity of surface-adhered, fiber-optic Strain gauges
    Applied Optics, 1992
    Co-Authors: Tomas Valis, D Hogg, Raymond M Measures
    Abstract:

    We have derived, based on established practice in experimental mechanics, an equation for calculating the thermal Apparent-Strain sensitivity of phase-modulated, surface-adhered, fiber-optic Strain sensors. This formulation permits the thermal performance of fiber-optic Strain gauges to be compared with conventional resistive gauges. This sensitivity for commonly used fiber-optic sensors is summarized.

  • Smart composite structures with embedded sensors
    Composites Engineering, 1992
    Co-Authors: Raymond M Measures
    Abstract:

    Fiber-optic sensors embedded within advanced composite materials represent a new branch of engineering with the potential to greatly enhance the confidence and use of these materials. An overview of our developments toward fiber-optic-based Smart Composite Structures is presented. This includes a review of our development of a full-scale fiber-optic damage assessment system for an aircraft composite leading edge and the confirmation of the feasibility of such a resident fiber-optic structural integrity monitoring system. We report on the development and characterization of fiber-optic Strain gauges that have been embedded within composite materials and used to measure the internal Strain field or detect load-induced acoustic emission from within composite specimens, and explore the feasibility of undertaking optoacoustic cure monitoring. A discussion is also provided of two issues: fiber-optic Strain sensitivity in light of the recent theoretical work of Sirkis and Haslach and thermally induced Apparent Strain. Lastly, mention is made of our passive, fast response, wavelength demodulation system for the Bragg grating sensor as this holds promise for the eventual development of a multiplexed, multisensing optoelectronic chip that could overcome the interconnect barrier to the practical implementation of Smart Structure technology. © 1992.

Ping Jiang - One of the best experts on this subject based on the ideXlab platform.

  • Strain hardening behaviors and Strain rate sensitivity of gradient grained fe under compression over a wide range of Strain rates
    Mechanics of Materials, 2016
    Co-Authors: Fuping Yuan, Ping Chen, Yanpeng Feng, Ping Jiang
    Abstract:

    In the present work, gradient-grained Fe was synthesized by means of surface mechanical grinding treatment, and then the compression behaviors of the coarse-grained Fe and the gradient-grained Fe were investigated under both quasi-static and dynamic loading conditions over a wide range of Strain rates (from 5 x 10(-4) to 10(4) s(-1)). After surface mechanical grinding treatment, equiaxed ultrafine grains, elongated lamellar ultrafine grains, full-developed sub-grains with dense dislocations walls, non-fully-developed dislocation cells, and deformed coarse grains are sequentially observed along the depth from the treated surface. The grain/cell size increases while the measured micro-hardness decreases along the depth for the gradient-grained Fe. The gradient-grained structure shows Apparent Strain hardening behaviors at all Strain rates up to 10(4) s(-1) although the Strain hardening exponent (n) for the gradient-grained Fe is smaller than that of the coarse-grained Fe at the same Strain rate. This Apparent hardening behavior is attributed to the hardening from both the coarse-grained center and the surface gradient layers when the Strain localization trend for the ultrafine-grained surface layers is suppressed by the coarse-grained center. The extra hardening might be due to the back stress hardening associated with the conStraint and mechanical incompatibility between different layers in the gradient-grained structure. The dynamic Strain rate sensitivity of the gradient-grained Fe is observed to be slightly larger than that of the coarse-grained Fe, which is controversial to the general observation that Strain rate sensitivity should decrease with reduction of grain size for BCC metals. The geometrically necessary dislocations associated with the back stress hardening and the grain size gradient result in additional increase in dislocation density, which may be the reason for the enhanced dynamic Strain rate sensitivity in the gradient-grained Fe even it has smaller average grain size compared to the coarse-grained Fe. The present results should provide insights for the applications of gradient-grained structure under dynamic conditions. (C) 2016 Elsevier Ltd. All rights reserved.

Alexander M Korsunsky - One of the best experts on this subject based on the ideXlab platform.

  • the effect of eigenStrain induced by ion beam damage on the Apparent Strain relief in fib dic residual stress evaluation
    Materials & Design, 2016
    Co-Authors: Enrico Salvati, Tan Sui, Alexander J G Lunt, Alexander M Korsunsky
    Abstract:

    Abstract FIB milling using Ga ions is known to be accompanied by implantation, multiplication of material defects, material property modification (e.g. amorphisation), inelastic shrinking/swelling and residual stress generation. These processes affect the reliability of the micro-ring-core method for residual stress evaluation. Safe use of this technique requires formulating approaches that provide quantitative criteria of the method's validity. In the present study this task is accomplished by proposing a numerical model based on eigenStrain. Parametric simulations were performed to identify the extent to which the FIB-DIC micro-ring-core measurements are affected. As an example of a real and relevant material system, the procedure was applied to silicon material. The curvature of an AFM cantilever due to FIB damage was monitored, and the eigenStrain magnitude determined by matching the model to observations. Using the resulting eigenStrain profile, parametric analysis was performed in terms of the pillar radius, and the elastic Strain field calculated at the pillar surface that is monitored in the FIB-DIC micro-ring-core method. An important property of the model is its versatility that allows it to be adapted to different milling conditions and geometries to determine the ultimate spatial resolution limits of the FIB-DIC method.

Michael P Wolcott - One of the best experts on this subject based on the ideXlab platform.

  • Rheology of HDPE-wood composites. I. Steady state shear and extensional flow
    Composites Part A: Applied Science and Manufacturing, 2004
    Co-Authors: T.-q. Li, Michael P Wolcott
    Abstract:

    Steady state flow of wood/high density polyethylene (HDPE) composites was studied using capillary rheometry to approach a fundamental understanding of the rheology of wood-polymer composite melts. Mooney slip analysis was applied to examine the nature of shear flow, indicating that the flow of wood/HDPE melts consist of contributions from both wall slip and viscous flow. Both simple viscous flow and yield stress behavior were observed, depending on wood species and content. It was observed that the dependence of wall slip velocity on shear stress in maple (Acer spp.) formulations resembles that of neat HDPE. In pine (Pinus spp.) formulations, however, wall slip rate is influenced by wood content. A converging flow technique was used to study the extensional flow. In contrast to shear flow properties, the extensional viscosity was found to depend much less on wood species. The effects of both wood content and species were observed through Trouton ratio. Strong inter-particle interaction was recorded for some filled melts as yield stress in shear flow and Apparent Strain hardening in extensional flow. © 2003 Elsevier Ltd. All rights reserved.

Kenji Higashi - One of the best experts on this subject based on the ideXlab platform.