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Статті в журналах з теми "Elastic deformation mapping":
1
Stefanelli, Ulisse. "Existence for dislocation-free finite plasticity." ESAIM: Control, Optimisation and Calculus of Variations 25 (2019): 21. http://dx.doi.org/10.1051/cocv/2018014.
Анотація:
This note addresses finite plasticity under the constraint that plastic deformations are compatible. In this case, the total elastoplastic deformation of the medium is decomposed as y = ye ○ yp, where the plastic deformation yp is defined on the fixed reference configuration and the elastic deformation ye is a mapping from the varying intermediate configuration yp(Ω). Correspondingly, the energy of the medium features both Lagrangian (plastic, loads) and not Lagrangian contributions (elastic). We present a variational formulation of the static elastoplastic problem in this setting and show that a solution is attained in a suitable class of admissible deformations. Possible extensions of the result, especially in the direction of quasistatic evolutions, are also discussed.
2
Dai, Ming, and Jian Hua. "Discussion on the conformal mapping of a half-plane onto a unit disk in anisotropic elasticity and related applications." Mathematics and Mechanics of Solids 26, no. 1 (August 8, 2020): 110–17. http://dx.doi.org/10.1177/1081286520948928.
Анотація:
The conformal mapping, which transforms a half-plane into a unit disk, has been used widely in studies involving an isotropic elastic half-plane under anti-plane shear or plane deformation. However, very little attention has been paid to the possibility of utilizing this mapping in the study of an anisotropic elastic half-plane under the same deformation. In this paper, we discuss a general case of an arbitrarily located anisotropic elastic half-plane that corresponds to several affine counterparts (resulting from corresponding complex variable formalism). We show that this mapping is indeed applicable to each of the affine half-planes if and only if the key parameters in the mapping satisfy simple geometrical conditions. In addition, we introduce the application of this mapping with the corresponding geometrical conditions to the related study of anisotropic thin films under two-dimensional deformation.
3
Guo, Peng, Xiang Wu, and Liangbi Wang. "New Solutions of Elastic Waves in an Elastic Rod under Finite Deformation." Journal of Applied Mathematics 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/495125.
Анотація:
The nonlinear wave equation of an elastic rod under finite deformation is solved by the extended mapping method. Abundant new exact traveling wave solutions for this equation are obtained, which contain trigonometric function solutions, solitary wave solutions, Jacobian elliptic function solutions, and Weierstrass elliptic function solutions. The method can be used in further works to establish more entirely new solutions for other kinds of nonlinear evolution equations arising in physics.
4
Fan, Rui Jun, Hong Chao Gao, and Zhou Zhou. "Parallelized Aeroelastic Investigation Based on Delaunay Graph Mapping." Applied Mechanics and Materials 444-445 (October 2013): 227–32. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.227.
Анотація:
In this paper, an effective and well robust dynamic grid deformation method based on Delaunay graph mapping is developed to solve the deformation of the 3-D hybrid multiblocks grids which is combined by near-wall viscosity grids and unstructured grids. Further more, the static aeroelastics problems of the standard model M6 elastic wing is investigated altogether by coupled with structure dynamic equation. The comparison, analysis and investigation were done as well. The CFD grids domain is subdivided into subdomains for parallel computation. And the program is carried out by MPI parallel computation standards.
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Kuo, Chang Hung, Siew Fern Lim, and Hung Ru Ho. "Cyclic Deformation Caused by Repeatedly Contact Loading." Applied Mechanics and Materials 883 (July 2018): 8–15. http://dx.doi.org/10.4028/www.scientific.net/amm.883.8.
Анотація:
An elastic-plastic contact stress analysis is presented to study cyclic plastic deformation of rolling elements under repeatedly contact loadings. The rolling contact is simulated by a Hertzian line contact loading translating over the surface of an elastic-plastic half-space, and the Chaboche nonlinear hardening rule is used to model the cyclic plastic behavior of contact components. A finite element procedure based on the return mapping algorithm is implemented to analyze the evolution plastic strains and residual stresses versus contact cycles. For the contact loading below the shakedown limit, p0/k=4, the plastic deformation occur only at first few contact cycles and become pure elastic in the subsequent cycles due to the existing residual stresses and material hardening. For the contact loading exceeding the shakedown limit, p0/k=7, the plastic strains increase progressively with each pass of contact cycles and result in plastic ratchetting. The normal residual stresses, however, quickly reach a steady state after few contact cycles.
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Zantopulos, H. "An Alternate Solution of the Deformation of a Cylinder Between Two Flat Plates." Journal of Tribology 110, no. 4 (October 1, 1988): 727–29. http://dx.doi.org/10.1115/1.3261720.
Анотація:
Using the method of conformal mapping, an alternate solution is obtained for the line contact deformation of a cylinder loaded between two flat plates. In this method, the elastic deformation of two half spaces, assuming an elliptical pressure distribution across the width of contact, does not have to be calculated relative to an arbitrarily selected stationary reference point.
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Ting, T. C. T., Y. Hu, and H. O. K. Kirchner. "Anisotropic Elastic Materials With a Parabolic or Hyperbolic Boundary: A Classical Problem Revisited." Journal of Applied Mechanics 68, no. 4 (January 2, 2001): 537–42. http://dx.doi.org/10.1115/1.1381393.
Анотація:
When an anisotropic elastic material is under a two-dimensional deformation that has a hole of given geometry Γ subjected to a prescribed boundary condition, the problem can be solved by mapping Γ to a circle of unit radius. It is important that (i) each point on Γ is mapped to the same point for the three Stroh eigenvalues p1,p2,p3 and (ii) the mapping is one-to-one for the region outside Γ. In an earlier paper it was shown that conditions (i) and (ii) are satisfied when Γ is an ellipse. The paper did not address to the case when Γ is an open boundary, such as a parabola or hyperbola that was studied by Lekhnitskii. We examine the mappings employed by Lekhnitskii for a parabola and hyperbola, and show that while the mapping for a parabola satisfies conditions (i) and (ii), the mapping for a hyperbola does not satisfy condition (i). Nevertheless, a valid solution can be obtained for the problem with a hyperbolic boundary, although the prescription of the boundary condition is restricted. We generalize Lekhnitskii’s solutions for general anisotropic elastic materials and for more general boundary conditions. Using known identities and new identities presented here, real form expressions are given for the displacement and hoop stress vector at the parabolic and hyperbolic boundary.
8
Wang, Shuangbu, Nan Xiang, Yu Xia, Lihua You, and Jianjun Zhang. "Real-time surface manipulation with $$C^{1}$$ continuity through simple and efficient physics-based deformations." Visual Computer 37, no. 9-11 (June 17, 2021): 2741–53. http://dx.doi.org/10.1007/s00371-021-02169-4.
Анотація:
AbstractWe present a novel but simple physics-based method to interactively manipulate surface shapes of 3D models with $$ C^1 $$ C 1 continuity in real time. A fourth-order partial differential equation involving a sculpting force originating from elastic bending of thin plates is proposed to define physics-based deformations and achieve $$ C^1 $$ C 1 continuity at the boundary of deformation regions. In order to obtain real-time physics-based surface manipulation, we construct a mapping relationship between a deformation region in a 3D coordinate space and a unit circle on a 2D parametric plane, formulate corresponding $$ C^1 $$ C 1 continuous boundary conditions for the unit circle, and obtain a simple analytical solution to describe the physics-based deformation in the unit circle caused by a sculpting force. After that, the obtained physics-based deformation is mapped back to the 3D coordinate space, and added to the original surface to create a new surface shape with $$ C^1 $$ C 1 continuity at the boundary of the deformation region. We also develop an interactive user interface as a plug-in of the 3D modelling software package Maya to achieve real-time surface manipulation. The effectiveness, easiness, real-time performance, and better realism of our proposed method is demonstrated by testing surface deformations on several 3D models and comparing with other methods and ground-truth deformations.
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Iwase, Kenji, Hirotaka Sato, Stefanus Harjo, Takashi Kamiyama, Takayoshi Ito, Shinichi Takata, Kazuya Aizawa, and Yoshiaki Kiyanagi. "In situlattice strain mapping during tensile loading using the neutron transmission and diffraction methods." Journal of Applied Crystallography 45, no. 1 (January 14, 2012): 113–18. http://dx.doi.org/10.1107/s0021889812000076.
Анотація:
In this study, the change in internal lattice strain in an iron plate during tensile deformation was investigated by performingin situmeasurements under applied force. The lattice strain was evaluated by neutron diffraction and Bragg-edge transmission. The neutron diffraction results showed that the averaged 110 lattice strain along the direction perpendicular to the applied force was between −422 and −109 × 10−6. The position dependence of the lattice strain and the change in the distribution of elastic strain in an iron plate with notches during tensile deformation was obtained by Bragg-edge transmission. It was also observed that, when the load increased over 30 kN, the area of plastic deformation increased around the positions of the notches.
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Hoshino, Kiyoshi, Daisuke Mori, and Motomasa Tomida. "An Optical Tactile Sensor Assuming Cubic Polynomial Deformation of Elastic Body." Journal of Robotics and Mechatronics 21, no. 6 (December 20, 2009): 780–88. http://dx.doi.org/10.20965/jrm.2009.p0780.
Анотація:
Assuming that the elastic body makes cubic polynomial deformation, we propose a compact three-dimensional (3D) optical tactile sensor for high-speed detection of three-axial directional force components. We constructed a 3D tactile sensor using thin, soft elastic and without pattern delineation or pigment injection such as that used in light-section measurement but having wider dynamic ranges and higher resolution. Conventional light-section measurement irradiating light onto sheets to measure objects requires a huge construction of the optical tactile sensor. Light-emitting diode (LED) sources are arranged around thin, deformable elastic membrane to obtain 3D force components from two-dimensional (2D) camera images taken using light sources of a minimum number of depth layers. Using two LED light sources - red and blue - around an elastic body, we estimate an object contact point pressing the elastic body and force magnitude and force incidence angle based on a mapping relationship predetermined through neural network learning from four ellipsoids formed by light irradiation and major and minor axis intersection points. To confirm that the elastic body forms cubic polynomial concavities at the point to rubber edges where force is applied based on X-, Y-, and Z-axes force components, we photographed elastic deformation and fitted curves into cubic polynomial expressions to investigate fitting accuracy. Fitting accuracy confirmed that cubic polynomials may reasonably approximate elastic deformation. We found that fitting curves onto cubic polynomials required two intersection points in addition to each edge of contact point and each of rubber edge point. Two is the minimum number of light sources required for irradiation. Experiments with this optical tactile sensor confirmed it to be effective in accurately estimating 3D elastic deformation, the object contact point, force magnitude, and force incidence angle.
Дисертації з теми "Elastic deformation mapping":
1
Ondračka, Václav. "Užití elektronové difrakce k mapování elastického napětí." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-449747.
Анотація:
Electron backscatter diffraction is a method that is well described and commonly used for orientation image mapping, including grain size estimation. The use of this method for measuring elastic deformation and rotations caused by plastic deformations is not so well decribed. This diploma thesis first describes the typical EBSD system. The information regarding the standard coordinate systems, grain orientation notation and system calibration is then used to create an open-source software for mapping elastic deformations and rotations inside a single grain or a monocrystal. This software uses data acquired during standard EBSD mapping on a commercial system.
Тези доповідей конференцій з теми "Elastic deformation mapping":
1
Lin, David C., and Ferenc Horkay. "Mapping the Elastic and Osmotic Properties of Cartilage Extracellular Matrix." In ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-206312.
Анотація:
The inhomogeneous distribution of crosslinks in polymer networks results in nonuniform swelling. Concomitant with this behavior is local variability in the elastic properties of synthetic and biopolymer gels. Articular cartilage exemplifies the compositional and structural complexities found in soft tissues. At the most basic level, cartilage extracellular matrix (ECM) is a relatively stiff network of collagen type II fibers with entangled hyaluronic acid chains and enmeshed aggrecan molecules. Despite significant differences in composition, synthetic and biological gels exhibit qualitatively similar responses (e.g., viscoelasticity and nonlinear stress-strain behavior at large deformation). Scaling theory [1] and experiments [2–3] have verified that the shear modulus (Ge) of chemically identical, fully swollen gels differing only in the degree of crosslinking is proportional to the polymer concentration (ce): (1)Ge=Acen where A and n are constants. In a good solvent, n = 2.25 [1]. Recent studies have shown that the power law applies to collagen gels, with n ≈ 2.68 [4]. In the general case, (2)G=Acen-mcm where G and c are the general shear modulus and polymer concentration, respectively, and m = 1/3 [5].
2
Xiong, Shangwu, Q. Jane Wang, Chih Lin, and Yansong Wang. "An Efficient Elastic Deformation Analysis Procedure for Simulating Conformal-Contact Transient Elastohydrodynamic Lubrication Systems." In STLE/ASME 2008 International Joint Tribology Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ijtc2008-71124.
Анотація:
A compliance operator, Eji, is often utilized to evaluate elastic deformation in the simulation of transient and steady state elastohydrodynamic lubrication of conformal-contact systems. The values of the compliance operator represent the elastic responses of all nodes when only one node is under a unit load. The accuracy of compliance operator values, computational cost, and storage size are important issues. Based on our previous study on steady-state conformal-contact elastohydrodynamic lubrication systems, an advanced method of selective-fine-mesh with selective storage is suggested, and a special technique of combined selective-fine-mesh with selective storage mapping is proposed. These two techniques enable an efficient elasticity procedure for the simulation of transient conformal-contact elastohydrodynamic lubrication systems.
3
Qian, Dong, and Qingjin Zheng. "Coarse-Grained Modeling and Simulation of Nanoscale Systems Based on Discrete Hyper-Elastic Model." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-68088.
Анотація:
The subject of developing equivalent continuum models from the atomistic models has attracted significant attention in recent years. An outstanding issue in extending the continuum model to smaller scales is the size effect. Such a size effect is intimately related to the discrete nature of the atomic structure and nonlocal interaction among the atoms. In many of the existing continuum approaches, discrete variables are introduced in the constitutive model to account for these non-continuum effects. In this paper, we present a discrete hyperelasticity model as an alternative. Our approach, however, is fundamentally different from the conventional approach in that it treats the concept of deformation mapping in the discrete sense. The resulting deformation measure is referred to as spatial secant and the corresponding material model is called the spatial secant model. We then formulate the potential energy density functional and derive stress-like measure based on the spatial secant. After a brief description on the formulation and its comparison with the classical hyper-elastic model, we show the application of this model to both low-dimensional carbon nanostructures and general three-dimensional nanostructures. The concept of geometric-exact mapping is discussed through the examples. Comparisons with full-scale molecular mechanics simulations are made to illustrate the robustness of this approach.
4
Xu, Heqin, Samer Mahmoud, Ashok Nana, and Doug Killian. "Crack Propagation Simulation: A Local Deformation-Based Mesh Mapping Method for Crack Modeling and a Direct Method for Residual Stress Representation in Welds." In ASME 2011 Pressure Vessels and Piping Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/pvp2011-57206.
Анотація:
Cracks found in a nuclear power plant reactor coolant system (RCS), such as primary water stress corrosion cracking (PWSCC) and intergranular stress corrosion cracking (IGSCC), usually have natural crack front shapes that can be very different from the idealized semi-elliptical or rectangular shapes considered in engineering handbooks and other analytical solutions based on limited shapes. Simplifications towards semi-elliptical shape or rectangular shape may potentially introduce unnecessary conservatism when the simplified shape has to contain the actual crack shape. On the other hand, it is very time-consuming to create a three-dimensional (3D) finite element (FE) model to simulate crack propagation in a natural shape using existing public-domain software like ABAQUS or ANSYS. In this study, a local deformation-based mesh-mapping (LDMM) method is proposed to model cracks with a natural front shape in any 3D structures. This methodology is first applied to model circumferential surface cracks with a natural crack front shape in the cross-sectional plane of a cylinder. The proposed new method can be applied to simulate both shallow and deep cracks. Also discussed in this paper is a direct method to reproduce welding residual stresses in the crack model using temperature fields combined with other sustained loads to predict crack propagations. With this novel LDMM method, natural crack fronts and non-planar crack faces can be easily modeled. The proposed new method can be used to generate a high-quality finite element model that can be used for both linear-elastic fracture mechanics (LEFM) and elastic-plastic fracture mechanics (EPFM) analyses. The study case illustrates that the proposed LDMM method is easy to implement and more efficient than the existing commercial software.
5
Geng, Haipeng, Shemiao Qi, and Lie Yu. "Numerical Calculation of the Structural Stiffness of Gas Foil Bearings." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22954.
Анотація:
The dynamics of a rotor supported in Gas Foil Bearings is strongly influenced by stiffness and damping properties of the bearings. In order to obtain the structural stiffness properties of Gas Foil Bearings, a coupled finite element method (FEM) is developed in this paper. The compressible gas lubricated Reynolds equation is transformed into a typical elliptic partial differential equation and solved by FEM. The elastic deformation equation and the contact boundary conditions between foils are solved by nonlinear contact finite method. A generalized numerical solving method for the elasto-aerodynamically coupled lubrication problem in the foil bearing is given with mesh mapping relationship between the two kind of finite element solving process above mentioned. The structural stiffness of the foil bearings with different parameters is estimated by using the numerical method. It is helpful to decide the structural parameters of the foil bearing.
6
Wang, Charlie C. L., Shiang-Fong Chen, Jin Fan, and Matthew M. F. Yuen. "Two-Dimensional Trimmed Surface Development Using a Physics-Based Model." In ASME 1999 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/detc99/dac-8634.
Анотація:
Abstract This paper presents a general method for parametric trimmed surface development. Parametric trimmed surface development is primarily used for flattening a 3D surface into a corresponding 2D pattern or surface. This method can be applied in computer aided design, texture mapping, ship building, etc. First, the surface is triangulated and mapped onto a plane. This initial planar mapping has the same topology as its original surface. Then, a spring-mass system is applied to deform the plane. The surface elastic deformation energy distribution is indicated by a color graph, which determines a surface cutting line. The method presented here can efficiently solve development problems for complex trimmed surfaces. Accuracy of a developed surface can easily be controlled locally. Thus, compared to earlier methods, this method provides more flexibility for solving CAD and CAM surfacing problems.
7
Nayebi, Ali, Azam Surmiri, and Hojjatollah Rokhgireh. "Shakedown-Ratcheting Analysis of a Spherical Pressure Vessel by Anisotropic Continuum Damage Mechanics." In ASME 2018 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/pvp2018-84065.
Анотація:
In cyclic loading and when plastic flow occurs, discontinuities grow. In this research, interaction diagram of Bree has been developed when the spherical pressure vessel contains discontinuities such as voids and microcracks. Bree’s diagram is used for ratcheting assessment of pressurized equipment in ASME III NH. Nature of these defects leads to an anisotropic damage. Anisotropic Continuum Damage Mechanics (CDM) is considered to account effects of these discontinuities on the behavior of the structure. Shakedown – ratcheting response of a hollow sphere under constant internal pressure and cyclic thermal loadings are studied by using anisotropic CDM theory coupled with nonlinear kinematic hardening of Armstrong-Frederick m’s model (A-F). Return mapping method is used to solve numerically the developed relations. Elastic, elastic shakedown, plastic shakedown and ratcheting regions are illustrated in the modified Bree’s diagram. Influence of anisotropic damage due to the plastic deformation is studied and it was shown that the plastic shakedown region is diminished because of the developed damage.
8
Nayebi, Ali, and Kourosh H. Shirazi. "Cyclic Loading of Beams Based on Kinematics Hardening Behavior Coupled With Isotropic Damage." In ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95239.
Анотація:
The kinematic hardening theory of plasticity based on the Prager model and incremental isotropic damage is used to evaluate the cyclic loading behavior of a beam under the axial, bending, and thermal loads. This allows damage to be path-dependent. The damage and inelastic deformation are incorporated and they are used for the analysis of the beam. The beam material is assumed to follow linear strain hardening property coupled with isotropic damage. The material strain hardening curves in tension and compression are assumed to be both identical for the isotropic material. Computational aspects of rate independent model is discussed and the constitutive equation of the rate independent plasticity coupled with the damage model are decomposed into the elastic, plastic and damage parts. Return Mapping Algorithm method is used for the correction of the elastoplastic state and for the damage model the algorithm is used according to the governed damage constitutive relation. The effect of the damage phenomenon coupled with the elastoplastic kinematic hardening is studied for deformation and load control loadings.
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Tandon, G. P., and R. Y. Kim. "Non-Destructive Evaluation of Damage Around Circular Holes in Bolted Composite Laminates." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14987.
Анотація:
One of the more formidable problems in composite research is the study of delamination and other failure modes in the vicinity of a circular hole in a laminate, e.g., a circular cut-out in a structure. In this problem, the singularity varies around the periphery of the hole as well as through the thickness of the laminate. Under tensile loading, the early failure modes in this problem consist of transverse cracks in various layers, so that delamination occurs only after other damage is precipitated, followed by fiber breakage leading to failure. A literature review of past work clearly shows that mechanical testing with simultaneous AE monitoring is a fruitful technique to study damage accumulation in composite systems. The acoustic-ultrasonic (AU) testing combines the high sensitivity of ultrasonics to internal damage and the method of acoustic emission technique to characterize elastic waves. As damage accumulates in the specimen along the wave path, the net internal damping increases and changes the wave parameters such as velocity, peak amplitude, duration, etc. accordingly. Additionally, a range of experimental results over the last decade has further shown that the mechanical deformation and electric resistance of carbon fiber reinforced polymers are coupled, so that the material is inherently a sensor of its own damage state. The monitoring of electric resistance and capacitance changes, linked to the modifications of the conduction paths in the composite, allows the detection of damage growth. It seems logical that a natural extension of these different approaches is the determination of damage mode, e.g., fiber breakage, matrix cracking or delamination, and damage size and position, based on combined measurements from these techniques. These multiple techniques will serve a two-fold purpose, namely, enable comparison as well as complement each other in case of incomplete damage mapping from one set of sensors For this study, we will consider carbon fiber-reinforced toughened bismaleimide, (IM7/5250-4) quasi-isotropic laminate coupons 12" long, 4" wide with hole at the center under tension. Figure 1 shows the damage which occurs around a 0.75" hole in a [45/0/-45/90]s graphite epoxy laminate obtained by radiography after unloading the test specimen from an applied stress of 50 Ksi. The failure stress for this laminate was 56.4 Ksi. Damage in the form of ply cracks in the 90, 45, and -45 plies and delamination around hole edges is clearly evident. The radiograph taken after unloading from a 50 Ksi stress level clearly shows the location and extent of damage, but contains no specific information about the sequence and the timing of damage events. Figure 2 shows stress-strain curves obtained from strain gages mounted at various distances away from the hole edge along with the far-field value. The stress-strain curves provide useful information regarding the initiation as well as the growth of the damage, as evidenced by jump in strain levels and onset of nonlinearity. Damage initiation is first picked up by the strain gage which is mounted closest to the hole edge at a stress level of 21 Ksi. Subsequently, other strain gages begin to sense damage growth as the applied stress level increases. The strain gage data provides useful information regarding initiation, growth and severity of damage, but it is difficult to assign specific damage modes and their location to the measurements. This example clearly demonstrates the needs, with the associated benefits, of the multiple sensor approach. In this work, three different hole sizes (0.25", 0.5" and 0.75") will be investigated. In addition to inherent resistivity measurements, we will also make strain measurements using gages coupled with simultaneous monitoring of AE events and attenuation of elastic waves using piezoelectric transducers and acceleration sensors. This example problem will enable us to examine the combined effects of cut-outs, matrix cracking, delamination and fiber breakage on the ability of various NDE techniques to assess damage. Integrating several nondestructive evaluation (NDE) techniques could provide a solution for real-time health monitoring.
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Bhushan, Bharat. "Nanotribology, Nanomechanics and Materials Characterization Studies Using Scanning Probe Microscopy." In ASME/STLE 2007 International Joint Tribology Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ijtc2007-44385.
Анотація:
At most solid-solid interfaces of technological relevance, contact occurs at numerous asperities. A sharp atomic/friction force microscope (AFM/FFM) tip sliding on a surface simulates just one such contact. However, asperities come in all shapes and sizes which can be simulated using tips of different shapes and sizes. AFM/FFM techniques are commonly used for tribological studies of engineering surfaces at scales ranging from atomic- to microscales. Studies include surface characterization, adhesion, friction, scratching/wear, boundary lubrication, and surface potential and capacitance mapping1–5. AFMs and their modifications are also used for nanomechanical characterization, which includes measurement and analysis of hardness, elastic modulus and viscoelastic properties, and in-situ localized deformation studies. State-of-the-art contact mechanics models have been developed and are used to analyze dry and wet contacting interfaces. Experimental data exhibit scale effects in adhesion, friction, wear, and mechanical properties, and a comprehensive model for scale effects due to adhesion/deformation and meniscus effects has been developed. Generally, coefficients of friction and wear rates on micro- and nanoscales are smaller, whereas hardness is greater. Therefore, micro/nanotribological studies may help define the regimes for ultra-low friction and near zero wear. New lubrication strategies such as the use of self-assembled monolayers promise to be very versatile and effective at these scales. To improve adhesion between biomolecules and the silicon based surfaces, chemical conjugation as well as surface patterning have been used. In the area of biomimetics, surface roughness present on lotus and other leaves has been measured and the surface films are characterized to understand the mechanisms responsible for superhydrophobicity (high contact angle). A model for surface-roughness-dependent contact angle has been developed and optimum distributions have been developed for superhydrophobic surfaces.