The Experts below are selected from a list of 4866 Experts worldwide ranked by ideXlab platform
M L Terranova - One of the best experts on this subject based on the ideXlab platform.
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Local Indentation modulus characterization via two contact resonance frequencies atomic force acoustic microscopy
Microelectronic Engineering, 2007Co-Authors: Daniele Passeri, A Bettucci, M Germano, M Rossi, A Alippi, A Fiori, Emanuela Tamburri, M L Terranova, S Orlanducci, Joost J VlassakAbstract:Atomic force acoustic microscopy is a dynamical AFM-based technique developed for non-destructive characterization of elastic properties of materials at micrometrical and sub-micrometrical scale. A standard AFM apparatus is equipped with a piezoelectric transducer exciting longitudinal oscillations at ultrasonic frequencies in the sample under investigation. Tip-sample contact stiffness is obtained through the values of the measured resonance frequencies of the cantilever contacting the sample surface, thus allowing one to obtain the value of the sample Indentation modulus. The paper describes a generalization of the technique: while performing topography, the first and the second contact resonance frequencies are acquired at each point of the scanned area. Data are then properly processed and acoustic images are obtained as a bi-dimensional pattern of the Indentation modulus over the imaged samples area. The technique is illustrated in two different kinds of sample: a metallographic (110) GaAs sample, prepared by incorporating GaAs single crystals into an epoxy matrix, and a diamond-like carbon film, deposited on a Mo substrate by laser ablation from a glassy carbon target.
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Local Indentation modulus characterization of diamondlike carbon films by atomic force acoustic microscopy two contact resonance frequencies imaging technique
Applied Physics Letters, 2006Co-Authors: Daniele Passeri, A Bettucci, M Germano, M Rossi, A Alippi, V Sessa, A Fiori, Emanuela Tamburri, M L TerranovaAbstract:Two contact resonance frequencies atomic force acoustic microscopy imaging technique has been used to evaluate Local Indentation modulus of a diamondlike carbon film deposited on a molybdenum foil by laser ablation from glassy carbon target. Acoustic images were obtained by measuring both first and second contact resonance frequency at each point of the scanned area, and then numerically evaluating Local contact stiffness and reconstructing an Indentation modulus bidimensional pattern. The wide difference of the Indentation modulus values allows to detect the presence of residual glassy carbon agglomerates in the diamondlike carbon film.
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effect of tip geometry on Local Indentation modulus measurement via atomic force acoustic microscopy technique
Review of Scientific Instruments, 2005Co-Authors: Daniele Passeri, A Bettucci, M Germano, M Rossi, A Alippi, M L Terranova, S Orlanducci, M CiavarellaAbstract:Atomic force acoustic microscopy (AFAM) is a dynamical AFM-based technique very promising for nondestructive analysis of Local elastic properties of materials. AFAM technique represents a powerful investigation tool in order to retrieve quantitative evaluations of the mechanical parameters, even at nanoscale. The quantitative determination of elastic properties by AFAM technique is strongly influenced by a number of experimental parameters that, at present, are not fully under control. One of such issues is that the quantitative evaluation require the knowledge of the tip geometry effectively contacting the surface during the measurements. We present and discuss an experimental approach able to determine, at first, tip geometry from contact stiffness measurements and, on the basis of the achieved information, to measure sample Indentation modulus. The reliability and the accuracy of the technique has been successfully tested on samples (Si, GaAs, and InP) with very well known structural and morphological properties and with Indentation modulus widely reported in literature.
Andrey Shipsha - One of the best experts on this subject based on the ideXlab platform.
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stability of the face layer of sandwich beams with sub interface damage in the foam core
Composite Structures, 2007Co-Authors: V Koissin, Vitaly Skvortsov, Andrey ShipshaAbstract:This paper addresses the effect of Local Indentation/impact damage on the bearing capacity of foam core sandwich beams subjected to edgewise compression. The considered damage is in a form of through-width zone of crushed core accompanied by a residual dent in the face sheet. It is shown that such damage causes a significant reduction of compressive strength and stiffness of sandwich beams. Analytical solutions estimating the Euler’s Local buckling load are obtained for two typical modes of damage. These solutions are validated through experimental investigation of three sandwich configurations. The results of the analytical analysis are in agreement with the experimental data.
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the inelastic quasi static response of sandwich structures to Local loading
Composite Structures, 2004Co-Authors: Vitali Koissin, Andrey Shipsha, Victor Iliev RizovAbstract:The paper addresses the inelastic quasi-static response of sandwich beams and panels with foam core to Localized loads. The plane and axisymmetric formulations for Local Indentation or Local low-velocity impact by a rigid body are considered; no overall bending is assumed. The governing equations for the face are derived using the Kirchhoff–Love static theory under the assumption that the core crushing follows elastic–ideally-plastic behavior. Analytical solutions are constructed on the basis of the principle of minimum work. The solutions allow predicting the face deflection, size of crushed core area and contact force. In general, the solutions are in good agreement with experimental data and finite element analysis.
Daniele Passeri - One of the best experts on this subject based on the ideXlab platform.
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Local Indentation modulus characterization via two contact resonance frequencies atomic force acoustic microscopy
Microelectronic Engineering, 2007Co-Authors: Daniele Passeri, A Bettucci, M Germano, M Rossi, A Alippi, A Fiori, Emanuela Tamburri, M L Terranova, S Orlanducci, Joost J VlassakAbstract:Atomic force acoustic microscopy is a dynamical AFM-based technique developed for non-destructive characterization of elastic properties of materials at micrometrical and sub-micrometrical scale. A standard AFM apparatus is equipped with a piezoelectric transducer exciting longitudinal oscillations at ultrasonic frequencies in the sample under investigation. Tip-sample contact stiffness is obtained through the values of the measured resonance frequencies of the cantilever contacting the sample surface, thus allowing one to obtain the value of the sample Indentation modulus. The paper describes a generalization of the technique: while performing topography, the first and the second contact resonance frequencies are acquired at each point of the scanned area. Data are then properly processed and acoustic images are obtained as a bi-dimensional pattern of the Indentation modulus over the imaged samples area. The technique is illustrated in two different kinds of sample: a metallographic (110) GaAs sample, prepared by incorporating GaAs single crystals into an epoxy matrix, and a diamond-like carbon film, deposited on a Mo substrate by laser ablation from a glassy carbon target.
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Local Indentation modulus characterization of diamondlike carbon films by atomic force acoustic microscopy two contact resonance frequencies imaging technique
Applied Physics Letters, 2006Co-Authors: Daniele Passeri, A Bettucci, M Germano, M Rossi, A Alippi, V Sessa, A Fiori, Emanuela Tamburri, M L TerranovaAbstract:Two contact resonance frequencies atomic force acoustic microscopy imaging technique has been used to evaluate Local Indentation modulus of a diamondlike carbon film deposited on a molybdenum foil by laser ablation from glassy carbon target. Acoustic images were obtained by measuring both first and second contact resonance frequency at each point of the scanned area, and then numerically evaluating Local contact stiffness and reconstructing an Indentation modulus bidimensional pattern. The wide difference of the Indentation modulus values allows to detect the presence of residual glassy carbon agglomerates in the diamondlike carbon film.
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effect of tip geometry on Local Indentation modulus measurement via atomic force acoustic microscopy technique
Review of Scientific Instruments, 2005Co-Authors: Daniele Passeri, A Bettucci, M Germano, M Rossi, A Alippi, M L Terranova, S Orlanducci, M CiavarellaAbstract:Atomic force acoustic microscopy (AFAM) is a dynamical AFM-based technique very promising for nondestructive analysis of Local elastic properties of materials. AFAM technique represents a powerful investigation tool in order to retrieve quantitative evaluations of the mechanical parameters, even at nanoscale. The quantitative determination of elastic properties by AFAM technique is strongly influenced by a number of experimental parameters that, at present, are not fully under control. One of such issues is that the quantitative evaluation require the knowledge of the tip geometry effectively contacting the surface during the measurements. We present and discuss an experimental approach able to determine, at first, tip geometry from contact stiffness measurements and, on the basis of the achieved information, to measure sample Indentation modulus. The reliability and the accuracy of the technique has been successfully tested on samples (Si, GaAs, and InP) with very well known structural and morphological properties and with Indentation modulus widely reported in literature.
Banghai Jiang - One of the best experts on this subject based on the ideXlab platform.
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Local Indentation of aluminum foam core sandwich beams at elevated temperatures
Composite Structures, 2016Co-Authors: Xuguang Chen, Banghai JiangAbstract:Abstract Sandwich structures with metallic foam core are sensitive to Local Indentation because of the low strength of the foam core and low bending stiffness of the thin face sheets. In this paper, Local Indentation responses of rigid supported and simply supported sandwich beams at elevated temperatures were studied. Quasi-static Indentation tests at different temperatures were carried out for rigid supported sandwich beams with aluminum face sheets and closed-cell aluminum foam core. The deformation and failure behaviors were explored and the Indentation load responses were compared. A dimensionless parameter was introduced and an analytical prediction model of Indentation load was established. Quasi-static Indentation tests were also carried out for simply supported sandwich beams and effects of face sheet thickness, core thickness and relative density of the foam core on the Indentation response and energy absorption of sandwich beams were discussed.
Richard Ororke - One of the best experts on this subject based on the ideXlab platform.
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a computational design framework for two layered elastic stamps in nanoimprint lithography and microcontact printing
Journal of Applied Physics, 2019Co-Authors: Hayden Taylor, Richard OrorkeAbstract:Mechanical micro- and nano-patterning processes rely on engineering the interactions between a stamp and a substrate to accommodate surface roughness and particle defects while retaining the geometric integrity of printed features. We introduce a set of algorithms for rapidly simulating the stamp–substrate contact, and we use them to show that advantageous behavior can occur when the stamp consists of a finite-thickness layer bonded to a layer with different elastic properties. The simulations use two-dimensional load-response functions describing in discrete space the response of a stamp surface's shape to a Localized unit load. These load-response functions incorporate the contributions both of Local, Indentation-like displacements and of plate-like bending of finite-thickness stamp layers. The algorithms solve iteratively for contact pressure distributions that, when spatially convolved with the load response, yield deformations consistent with the properties of the stamp and the substrate. We investigate three determinants of stamp performance: conformation to sinusoidal substrate topographies, distortion of material around stamp protrusions, and conformation to isolated spherical dust particles trapped between the stamp and the substrate. All simulation results are encapsulated in dimensionless models that can be applied to the efficient selection of stamp geometries, materials, and loading conditions. A particularly striking finding is that a stamp with a finite-thickness compliant coating bonded to a more rigid support can conform more closely to a trapped particle under a given load than a homogeneous stamp with the properties of the coating. This finding could be used to minimize the impact of particle defects on patterning processes.Mechanical micro- and nano-patterning processes rely on engineering the interactions between a stamp and a substrate to accommodate surface roughness and particle defects while retaining the geometric integrity of printed features. We introduce a set of algorithms for rapidly simulating the stamp–substrate contact, and we use them to show that advantageous behavior can occur when the stamp consists of a finite-thickness layer bonded to a layer with different elastic properties. The simulations use two-dimensional load-response functions describing in discrete space the response of a stamp surface's shape to a Localized unit load. These load-response functions incorporate the contributions both of Local, Indentation-like displacements and of plate-like bending of finite-thickness stamp layers. The algorithms solve iteratively for contact pressure distributions that, when spatially convolved with the load response, yield deformations consistent with the properties of the stamp and the substrate. We investig...