Có 20+ tài liệu thuộc chủ đề "Mechanical sciences"
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In this paper we develop and study an archetypal model to explore the nonlinear dynamic interactions between galloping at an incipient sub-critical Hopf bifurcation of a structure with shell- like buckling behaviour that is gravity-loaded to approach a sub-critical pitch-fork bifurcation. Meanwhile, for the structural component, we consider a variant of the propped-cantilever model that is widely used to illustrate...
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This paper provides for the first time in the open literature the design procedure, and subsequent analysis of the turbine performance of a turbine adequate for supersonic axial pulsating fl ows, as those encountered in innovative combustors. A fundamental issue in supersonic passages is to ensure the normal shock at the start of the engine is swallowed through the turbine...
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Exciting the system at a single resonant frequency highlights the in fl uence of clearance and base excitation amplitude on the beam responses. The frequency sweep study shows the sensitivity of the power generated to the contact stiffness, damping and clearance between the beams. The power generated by the coupled system from the non-linear impact is sensitive to the thickness...
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At a fi ner scale this transition is explained by minute energetic requirements for the evolution of the defect structure. Through that an accurate control of the size of the localization zone (important in consideration of the size effects) on the course of deformation is supplied. In addition, the problem of pathological mesh depen- dence of the numerical simulations is...
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Among these methods, slab theory produces the most accurate description of the stresses within the roll gap.. Here, a model is described for sandwich sheet rolling that captures through-thickness variation of the stress fi elds while remaining quick to evaluate. Domanti and McElwain [8] make an additional assumption that the reduction of the sheet thickness is small. The assumptions made...
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The latter appears to be an eminent requirement for predicting the qualitative effect of the evolving dislocation microstructures under orthogonal loading path changes, i.e., the cross hardening. Finally, the rate dependence of the plastic response is incorporated using Johnson–Cook type formula- tion. The macroscopic behavior of the polycrystalline metals is closely linked to the underlying microstructure and its evolution.. investigated...
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tom landing level to the centre of the compensating sheave. lateral out of plane direction of the i th rope. D irn V/W coefficients that account for the quadratic nonlinear coupling of the system of the i th rope in the lateral in plane and out of plane directions. E G modulus of elasticity of the. EA i product of...
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Monitoring power-law creep using the Failure Forecast Method. Instead, the integrity of a component should be established through direct measurement of the response of the component to the operating conditions. an increase in strain leads to an increasing strain rate. A range of strain rate based assessments have been proposed in the literature but it is proposed that the Failure...
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Biofidelic finite element modelling of brain trauma: Importance of the scalp in simulating head impact. Recent work has highlighted the importance of the scalp in head impact kinematics, particularly for oblique head impacts, where high rotational accelerations are experienced. The present work reports the development of a biofidelic finite element head model which, among other refinements, accurately reflects the mechanical...
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Also, the influence of the porosity of the initial packing on the properties of the material is investigated. Simulation results have shown that due to the heterogeneous macroscopic structure and unequal material distribution in nodes, struts or near interstitial pores, strong inhomogeneities of the stress distribution arise. Reducing the overall porosity or an additional coating of the structure with a...
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The discriminatory power of the texture information is evaluated based on the Fisher’s Discriminant Ratio and feature correlations are identified and quantified. It is found that a small subset of the investigated texture features is highly significant for all experiments. At the same time, it is shown that linear classifiers are not sufficient to robustly distinguish the state of the...
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The cable is subjected to a base-motion (kinematic) excitation due to a low frequency sway of the structure. The development of the deterministic equations of motion and of the stochastic models describing the lateral dynamic behaviour of the cable is presented. Due to the time-varying length of the cable, the system exhibits nonstationary dynamic characteristics and its response is governed...
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Bragg scattering is exhibited by periodic lattices in the high frequency regime where the propagating wavelength is of the same order as the lattice constant. Based on the primary medium of the wave propagation, LRAMs can be further classified as solid (e.g. The micro-inertial effects resulting from the low frequency vibration modes of the inclusion induce the local resonance action....
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The current work investigates the effect of the nodal mass on the macroscopic mechanical behavior of nanoporous metals using the Finite Element Method. A nodal corrected beam modeling concept is introduced that allows local incorporation of the effective elastoplastic mechanical behavior of the nodal mass in the nodal area of a representative volume element (RVE). From the results of the...
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Non-contact and non-destructive Lamb wave generation using laser-induced plasma shock wave. Lamb wave. This paper proposes a non-contact and non-destructive method to generate Lamb waves against a target structure using the impulse excitation force generated by laser-induced plasma (LIP). A 2024 aluminum alloy plate is used as the test piece in the experiment, and the dynamic characteristics of the Lamb...
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If these units are identical, then the mechanical behaviour of the structure is uniform throughout, meaning that it is not able to adapt to changeable loading conditions. Using kinematic analysis, we show how geometric parameters of the folding pattern can be varied to create both rigid foldable and self locking stages. Making use of the superior ability of origami to...
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This paper proves that, given a Load-Induced Thermal Strain (LITS) curve able to accurately describe the uniax- ial LITS development for a specific type of concrete and temperatures up to 500 °C, a more accurate prediction of the 3D LITS state is obtained through a confinement-dependent 3D implementation than through the classic confinement-independent approach. In particular, a new model is...
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Nonlinear mechanics Cylindrical cantilever shells Global transverse shear Ovalisation. This paper presents a comprehensive computational investigation into the nonlinear elastic buckling response of perfect and imperfect thin cantilever cylinders under global transverse shear. Two imperfection forms were applied depending on the length of the cylinder: the linear buckling eigenmode for short cylinders and a realistic weld depression imperfection for long...
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We demonstrate this toughen- ing effect using synchrotron X-ray diffraction and digital image correlation measurements of the crack tip region in a ductile ferritic steel. Residual stress contributes to the rate at which strain energy is released during the ad- vance of a crack, modifying the material’s apparent toughness. The crack tip strain energy release rate in an ideal non-linear...
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Surface texture. Machining-process-induced surface texture plays an indispensable role in determining surface integrity and final functional performance of the machined components. were quantitatively characterized and analyzed using 2D and 3D surface texture parameters. Correlation between the 3D surface texture parameters or statistical functions with the corresponding functional perfor- mance, e.g. This study emphasized on the effectiveness and veracity of the...