The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Colin R. Mcinnes - One of the best experts on this subject based on the ideXlab platform.
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Inverse problem for shape control of flexible space reflectors using distributed solar pressure
Smart Materials and Structures, 2014Co-Authors: Andreas Borggrafe, Jeannette Heiligers, Matteo Ceriotti, Colin R. McinnesAbstract:This paper investigates controlled Elastic Deflection of thin circular space reflectors using an inverse problem approach to non-linear thin membrane theory. When changing the surface reflectivity across the membrane, the distributed loads due to ambient solar radiation pressure can be manipulated optically, thus controlling the surface shape without using mechanical or piezo-electric systems. The surface reflectivity can in principle be modulated using uniformly distributed thin-film electro-chromic coatings. We present an analytic solution to the inverse problem of finding the necessary reflectivity distribution that creates a specific membrane Deflection, for example that of a parabolic reflector. Importantly, the reflectivity distribution across the surface is found to be independent of membrane size, thickness and solar distance, enabling engineering of the reflectivity distribution directly during the manufacture of the membrane.
Cyprien Gay - One of the best experts on this subject based on the ideXlab platform.
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Internal relaxation time in immersed particulate materials
Physical Review E : Statistical Nonlinear and Soft Matter Physics, 2010Co-Authors: Pierre Rognon, Itai Einav, Cyprien GayAbstract:We study the dynamics of the solid to liquid transition for a model material made of Elastic particles immersed in a viscous fluid. The interaction between particle surfaces includes their viscous lubrication, a sharp repulsion when they get closer than a tuned steric length and their Elastic Deflection induced by those two forces. We use Soft Dynamics to simulate the dynamics of this material when it experiences a step increase in the shear stress and a constant normal stress. We observe a long creep phase before a substantial flow eventually establishes. We find that the typical creep time relies on an internal relaxation process, namely the separation of two particles driven by the applied stress and resisted by the viscous friction. This mechanism should be relevant for granular pastes, living cells, emulsions and wet foams.
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Soft Dynamics simulation. 2. Elastic spheres undergoing a T1 process in a viscous fluid
European Physical Journal E: Soft matter and biological physics, 2009Co-Authors: Pierre Rognon, Cyprien GayAbstract:Robust empirical constitutive laws for granular materials in air or in a viscous fluid have been expressed in terms of timescales based on the dynamics of a single particle. However, some behaviours such as viscosity bifurcation or shear localization, observed also in foams, emulsions, and block copolymer cubic phases, seem to involve other micro-timescales which may be related to the dynamics of local particle reorganizations. In the present work, we consider a T1 process as an example of a rearrangement. Using the Soft Dynamics simulation method introduced in the first paper of this series, we describe theoretically and numerically the motion of four Elastic spheres in a viscous fluid. Hydrodynamic interactions are described at the level of lubrication (Poiseuille squeezing and Couette shear flow) and the Elastic Deflection of the particle surface is modeled as Hertzian. The duration of the simulated T1 process can vary substantially as a consequence of minute changes in the initial separations, consistently with predictions. For the first time, a collective behaviour is thus found to depend on a parameter other than the typical volume fraction of particles.
G.-c. Vosniakos - One of the best experts on this subject based on the ideXlab platform.
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Prediction of workpiece Elastic Deflections under cutting forces in turning
Robotics and Computer-Integrated Manufacturing, 2006Co-Authors: P.g. Benardos, S. Mosialos, G.-c. VosniakosAbstract:One of the problems faced in turning processes is the Elastic deformation of the workpiece due to the cutting forces resulting in the actual depth of cut being different than the desirable one. In this paper, a cutting mechanism is described suggesting that the above problem results in an over-dimensioned part. Consequently, the problem of determining the workpiece Elastic Deflection is addressed from two different points of view. The first approach is based on solving the analytical equations of the Elastic line, in discretized segments of the workpiece, by considering a stored modal energy formulation due to the cutting forces. Given the mechanical properties of the workpiece material, the geometry of the final part and the cutting force values, this numerical method can predict the Elastic Deflection. The whole approach is implemented through a Microsoft Excel(C) workbook. The second approach involves the use of artificial neural networks (ANNs) in order to develop a model that can predict the dimensional deviation of the final part by correlating the cutting parameters and certain workpiece geometrical characteristics with the deviations of the depth of cut. These deviations are calculated with reference to final diameter values measured with precision micrometers or on a CMM. The verification of the numerical method and the development of the ANN model were based on data gathered from turning experiments conducted on a CNC lathe. The results support the proposed cutting mechanism. The numerical method qualitatively agrees with the experimental data while the ANN model is accurate and consistent in its predictions. (C) 2006 Elsevier Ltd. All rights reserved
Andreas Borggrafe - One of the best experts on this subject based on the ideXlab platform.
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Inverse problem for shape control of flexible space reflectors using distributed solar pressure
Smart Materials and Structures, 2014Co-Authors: Andreas Borggrafe, Jeannette Heiligers, Matteo Ceriotti, Colin R. McinnesAbstract:This paper investigates controlled Elastic Deflection of thin circular space reflectors using an inverse problem approach to non-linear thin membrane theory. When changing the surface reflectivity across the membrane, the distributed loads due to ambient solar radiation pressure can be manipulated optically, thus controlling the surface shape without using mechanical or piezo-electric systems. The surface reflectivity can in principle be modulated using uniformly distributed thin-film electro-chromic coatings. We present an analytic solution to the inverse problem of finding the necessary reflectivity distribution that creates a specific membrane Deflection, for example that of a parabolic reflector. Importantly, the reflectivity distribution across the surface is found to be independent of membrane size, thickness and solar distance, enabling engineering of the reflectivity distribution directly during the manufacture of the membrane.
Saeid Amini - One of the best experts on this subject based on the ideXlab platform.
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Analytical and experimental approaches to study Elastic Deflection of thin strip in ultrasonic-assisted drilling process:
Proceedings of the Institution of Mechanical Engineers Part E: Journal of Process Mechanical Engineering, 2017Co-Authors: Reza Teimouri, Saeid AminiAbstract:During machining of thin material, workpiece endures Deflection due to cutting forces that negatively influence dimensional tolerances and machined surface quality. An applicable method for the res...