The Experts below are selected from a list of 93804 Experts worldwide ranked by ideXlab platform
Jaehong Lee - One of the best experts on this subject based on the ideXlab platform.
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interaction curves for vibration and buckling of thin walled composite box beams under axial loads and end moments
Applied Mathematical Modelling, 2010Co-Authors: Jaehong LeeAbstract:Interaction curves for vibration and buckling of thin-walled composite box beams with arbitrary lay-ups under constant axial loads and equal end moments are presented. This model is based on the classical lamination theory, and accounts for all the Structural Coupling coming from material anisotropy. The governing differential equations are derived from the Hamilton’s principle. The resulting Coupling is referred to as triply flexural–torsional coupled vibration and buckling. A displacement-based one-dimensional finite element model with seven degrees of freedoms per node is developed to solve the problem. Numerical results are obtained for thin-walled composite box beams to investigate the effects of axial force, bending moment, fiber orientation on the buckling loads, buckling moments, natural frequencies and corresponding vibration mode shapes as well as axial-moment–frequency interaction curves.
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Geometrically nonlinear analysis of thin-walled open-section composite beams
Computers & Structures, 2010Co-Authors: Jaehong LeeAbstract:A geometrically nonlinear model for general thin-walled open-section composite beams with arbitrary lay-ups under various types of loadings based on the classical lamination theory is presented. It accounts for all Structural Coupling coming from the material anisotropy and geometric nonlinearity. Nonlinear governing equations are derived and solved by means of an incremental Newton-Raphson method. The finite element model that accounts for the geometric nonlinearity in the von Karman sense is developed to solve the problem. Numerical results are obtained for thin-walled composite Z-beam and I-beam to investigate effects of geometric nonlinearity, fiber orientation and warping restraint on the flexural-torsional response.
Thuc P Vo - One of the best experts on this subject based on the ideXlab platform.
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flexural torsional coupled vibration and buckling of thin walled open section composite beams using shear deformable beam theory
International Journal of Mechanical Sciences, 2009Co-Authors: Thuc P VoAbstract:A general analytical model based on shear-deformable beam theory has been developed to study the flexural–torsional coupled vibration and buckling of thin-walled open section composite beams with arbitrary lay-ups. This model accounts for all the Structural Coupling coming from the material anisotropy. The seven governing differential equations for coupled flexural–torsional–shearing vibration are derived from Hamilton's principle. The resulting Coupling is referred to as sixfold coupled vibration. Numerical results are obtained to investigate effects of shear deformation, fiber orientation and axial force on the natural frequencies, corresponding mode shapes as well as load–frequency interaction curves.
Daniel Herschlag - One of the best experts on this subject based on the ideXlab platform.
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Structural Coupling Throughout the Active Site Hydrogen Bond Networks of Ketosteroid Isomerase and Photoactive Yellow Protein.
Journal of the American Chemical Society, 2018Co-Authors: Margaux M. Pinney, Jason P Schwans, Aditya Natarajan, Filip Yabukarski, David M. Sanchez, Fang Liu, Ruibin Liang, Tzanko Doukov, Todd J. Martinez, Daniel HerschlagAbstract:Hydrogen bonds are fundamental to biological systems and are regularly found in networks implicated in folding, molecular recognition, catalysis, and allostery. Given their ubiquity, we asked the fundamental questions of whether, and to what extent, hydrogen bonds within networks are Structurally coupled. To address these questions, we turned to three protein systems, two variants of ketosteroid isomerase and one of photoactive yellow protein. We perturbed their hydrogen bond networks via a combination of site-directed mutagenesis and unnatural amino acid substitution, and we used 1H NMR and high-resolution X-ray crystallography to determine the effects of these perturbations on the lengths of the two oxyanion hole hydrogen bonds that are donated to negatively charged transition state analogs. Perturbations that lengthened or shortened one of the oxyanion hole hydrogen bonds had the opposite effect on the other. The oxyanion hole hydrogen bonds were also affected by distal hydrogen bonds in the network, w...
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Structural Coupling Throughout the Active Site Hydrogen Bond Networks of Ketosteroid Isomerase and Photoactive Yellow Protein
2018Co-Authors: Margaux M. Pinney, Jason P Schwans, Aditya Natarajan, Filip Yabukarski, David M. Sanchez, Fang Liu, Ruibin Liang, Tzanko Doukov, Todd J. Martinez, Daniel HerschlagAbstract:Hydrogen bonds are fundamental to biological systems and are regularly found in networks implicated in folding, molecular recognition, catalysis, and allostery. Given their ubiquity, we asked the fundamental questions of whether, and to what extent, hydrogen bonds within networks are Structurally coupled. To address these questions, we turned to three protein systems, two variants of ketosteroid isomerase and one of photoactive yellow protein. We perturbed their hydrogen bond networks via a combination of site-directed mutagenesis and unnatural amino acid substitution, and we used 1H NMR and high-resolution X-ray crystallography to determine the effects of these perturbations on the lengths of the two oxyanion hole hydrogen bonds that are donated to negatively charged transition state analogs. Perturbations that lengthened or shortened one of the oxyanion hole hydrogen bonds had the opposite effect on the other. The oxyanion hole hydrogen bonds were also affected by distal hydrogen bonds in the network, with smaller perturbations for more remote hydrogen bonds. Across 19 measurements in three systems, the length change in one oxyanion hole hydrogen bond was propagated to the other, by a factor of −0.30 ± 0.03. This common effect suggests that hydrogen bond Coupling is minimally influenced by the remaining protein scaffold. The observed Coupling is reproduced by molecular mechanics and quantum mechanics/molecular mechanics (QM/MM) calculations for changes to a proximal oxyanion hole hydrogen bond. However, effects from distal hydrogen bonds are reproduced only by QM/MM, suggesting the importance of polarization in hydrogen bond Coupling. These results deepen our understanding of hydrogen bonds and their networks, providing strong evidence for long-range Coupling and for the extent of this Coupling. We provide a broadly predictive quantitative relationship that can be applied to and can be further tested in new systems
Marcel Van Der Heijden - One of the best experts on this subject based on the ideXlab platform.
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vibration hotspots reveal longitudinal funneling of sound evoked motion in the mammalian cochlea
Nature Communications, 2018Co-Authors: Nigel P Cooper, Anna Vavakou, Marcel Van Der HeijdenAbstract:The micromechanical mechanisms that underpin tuning and dynamic range compression in the mammalian inner ear are fundamental to hearing, but poorly understood. Here, we present new, high-resolution optical measurements that directly map sound-evoked vibrations on to anatomical structures in the intact, living gerbil cochlea. The largest vibrations occur in a tightly delineated hotspot centering near the interface between the Deiters’ and outer hair cells. Hotspot vibrations are less sharply tuned, but more nonlinear, than basilar membrane vibrations, and behave non-monotonically (exhibiting hyper-compression) near their characteristic frequency. Amplitude and phase differences between hotspot and basilar membrane responses depend on both frequency and measurement angle, and indicate that hotspot vibrations involve longitudinal motion. We hypothesize that Structural Coupling between the Deiters’ and outer hair cells funnels sound-evoked motion into the hotspot region, under the control of the outer hair cells, to optimize cochlear tuning and compression.
J L Curielsosa - One of the best experts on this subject based on the ideXlab platform.
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3 d local mesh refinement xfem with variable node hexahedron elements for extraction of stress intensity factors of straight and curved planar cracks
Computer Methods in Applied Mechanics and Engineering, 2017Co-Authors: Zhen Wang, Tinh Quoc Bui, Satoyuki Tanaka, Chuanzeng Zhang, Sohichi Hirose, J L CurielsosaAbstract:Abstract A novel local mesh refinement approach for fracture analysis of three-dimensional (3-D) linear elastic solids is developed, considering both 3-D straight and curved planar cracks. The present local mesh refinement formulation is a combination of the extended finite element method (XFEM), variable-node hexahedron elements, and a posteriori error indicator. Our 3-D formulation using hexahedron elements rigorously embraces a posteriori error estimation scheme, a Structural Coupling scale-meshes strategy and an enrichment technique. Local mesh refinement is only performed where it is needed, e.g., a vicinity of crack, through an error estimator based on the recovery stress procedure. To treat the mismatching problem induced by different scale-meshes in the domain, a Structural Coupling scheme employing variable-node transition hexahedron elements based on the generic point interpolation with an arbitrary number of nodes on each of their faces is presented. The 3-D finite element approximations of field variables are enhanced by enrichments so that the mesh is fully independent of the crack geometry. The displacement extrapolation method is taken for the evaluation of linear elastic fracture parameters (e.g., stress intensity factors—SIFs). To show the accuracy and performance of our proposed 3-D formulation, six numerical examples of planar 3-D straight and curved shaped cracks with single and mixed-mode fractures and different configurations are considered and analyzed. The SIFs computed by the developed method are validated with respect to analytical solutions and the ones derived from the conventional XFEM. Associated with an adaptive process, the present 3-D formulation allows the analysts to gain a desirable accuracy with a few trials, which is suited for practices purpose.
