1,721,077 research outputs found
Isogeometric treatment of large deformation contact and debonding problems with T-splines: a review
Full text linkWithin a setting where the isogeometric analysis
(IGA) has been successful at bringing two different research
fields together, i.e. Computer Aided Design (CAD)
and numerical analysis, T-spline IGA is applied in this
work to frictionless contact and mode-I debonding problems
between deformable bodies in the context of large deformations.
Based on the concept of IGA, the smooth basis
functions are adopted to describe surface geometries and
approximate the numerical solutions, leading to higher accuracy
in the contact integral evaluation. The isogeometric
discretizations are here incorporated into an existing
finite element framework by using Bézier extraction, i.e. a
linear operator which maps the Bernstein polynomial basis
on Bézier elements to the global isogeometric basis. A
recently released commercial T-spline plugin for Rhino is
herein used to build the analysis models adopted in this
study
Structural and Computational Mechanics Book Series
No full textThe Esculapio Series in “Structural and Computational Mechanics” has been inaugurated with the aim of arranging a series of books in these key fields related to academic research, education and industrial applications. The Esculapio Series publishes high-level texts for academic students, deep studies on good practice and industrial technology, interesting and fundamental research topics related to industrial development and engineering practices. The readership encapsulates undergraduate and PhD students, researchers, scientists and free-lancers within applied mechanics topics. Civil/structural, mechanical, aerospace, naval, nuclear, automotive, materials, environmental, electrical, and biomedical engineers could benefit from this book series. The present book series would be the natural home for authors proficient in mechanics of materials, mechanics of structures as well as computational and applied mechanics
T-splines discretizations for large deformation contact problems
Full text linkA T-spline-based isogeometric analysis is applied to frictional contact problems between deformable bodies in the context of large deformations. The continuum is discretized with cubic T-splines and cubic NURBS (Non-Uniform Rational B- Splines) for comparison purposes. A Gauss-point-to-surface (GPTS) formulation is combined with the penalty method to treat the normal and friction contact constraints in the discretized setting. It is demonstrated that the proposed formulation combined with analysis-suitable T-spline interpolations, is a computationally accurate and efficient technology for local and global solutions of contact problems. T-spline analysis models are generated using commercially available T-spline modeling software without intermediate mesh generation or geometry clean-up step
Isogeometric treatment of large deformation contact and debonding problems with NURBS and T-splines
No full textStructural study of masonry buttresses: the stepped form
No full textThe stability of masonry buttresses under horizontal forces is of paramount importance for the safety of vaulted structures, and yet has been the subject of limited studies. In particular, buttresses of non-rectangular geometries such as trapezoidal and stepped buttresses, which are typical of Gothic architecture, have not been sufficiently investigated. This study follows on from a companion paper devoted to masonry with trapezoidal buttresses. Based on similar modelling approaches and assumptions, the present paper aims to predict the failure of stepped buttresses. The analytical solution, obtained by treating masonry as a continuum with no tension resistance and accounting for the formation of a fracture prior to collapse, is compared with the predictions of the discrete element method. The numerical approach considers masonry as an assemblage of rigid blocks with no-tension frictional joints and is based on time-stepping integration of the equations of motion of the individual blocks. The relative efficiency of different buttress shapes for a given total volume is also compared, and an example buttress is used as a benchmark to demonstrate the practical applicability of the proposed models
Nonlinear Axial-Lateral Coupled Vibration of Functionally Graded-Fiber Reinforced Composite Laminated (FG-FRCL) Beams Subjected to Aero-Thermal Loads
No full textThis paper studies the nonlinear axial-lateral coupled vibration of functionally graded-fiber reinforced composite laminated (FG-FRCL) cantilever beams subjected to aero-thermal loads. The nonlinear partial differential equations governing the problem are determined based on the Euler-Bernoulli beam theory using the von Kármán-type geometrical nonlinearities. The Galerkin method is then applied to discretize the differential equations and to transform them into a nonlinear ordinary differential equation. The coupled ordinary differential equations are solved analytically using the method of multiple time scales (MTS) to study the nonlinear forced vibration time response of the selected FG-FRCL structures, where a large parametric study checks for the effect of power-index, uniform temperature rise, velocity of the free stream air and Mach number on their axial and lateral response, with interesting insights from a scientific and design purposes
Static Analysis of Doubly-Curved Shell Structures of Smart Materials and Arbitrary Shape Subjected to General Loads Employing Higher Order Theories and Generalized Differential Quadrature Method
No full textThe article proposes an Equivalent Single Layer (ESL) formulation for the linear static analysis of arbitrarily-shaped shell structures subjected to general surface loads and boundary conditions. A parametrization of the physical domain is provided by employing a set of curvilinear principal coordinates. The generalized blending methodology accounts for a distortion of the structure so that disparate geometries can be considered. Each layer of the stacking sequence has an arbitrary orientation and is modelled as a generally anisotropic continuum. In addition, re-entrant auxetic three-dimensional honeycomb cells with soft-core behaviour are considered in the model. The unknown variables are described employing a generalized displacement field and pre-determined through-the-thickness functions assessed in a unified formulation. Then, a weak assessment of the structural problem accounts for shape functions defined with an isogeometric approach starting from the computational grid. A generalized methodology has been proposed to define two-dimensional distributions of static surface loads. In the same way, boundary conditions with three-dimensional features are implemented along the shell edges employing linear springs. The fundamental relations are obtained from the stationary configuration of the total potential energy, and they are numerically tackled by employing the Generalized Differential Quadrature (GDQ) method, accounting for nonuniform computational grids. In the post-processing stage, an equilibrium-based recovery procedure allows the determination of the three-dimensional dispersion of the kinematic and static quantities. Some case studies have been presented, and a successful benchmark of different structural responses has been performed with respect to various refined theories
General boundary conditions implementation for the static analysis of anisotropic doubly-curved shells resting on a winkler foundation
No full textIn the present work an Equivalent Single Layer (ESL) formulation is proposed for the static analysis of doubly-curved anisotropic structures of arbitrary geometry and variable stiffness resting on a Winkler elastic foundation. In-plane and out-of-plane general distributions of linear elastic springs are provided for the implementation of general external constraints along the edges of the structure. The structure is geometrically described accounting for the principal curvatures of the shell object of analysis. A generalized set of blending functions based on Non-Uniform Rational Basis Spline (NURBS) curves is adopted so that arbitrary shaped structures can be modelled with the same approach. The fundamental governing equations are obtained in terms of displacement field unknowns, which has been effectively described accounting for a unified formulation based on the minimum potential energy principle. General anisotropic lamination schemes are considered, setting a general orientation of each lamina, as well as all possible material symmetries. The numerical implementation is performed by means of the Generalized Differential Quadrature (GDQ) method, thus allowing a strong formulation of the structural problem. A series of validation examples is performed on shells with zero, single and double curvatures in which the static structural response provided with the proposed formulation has been compared to that obtained from a refined three-dimensional finite element model, showing a great accordance between these different approaches. The research shows that the employment of higher order theories, together with the GDQ method, allows to obtain very accurate results with a reduced computational cost, compared to finite element simulations
Transient response of oscillated carbon nanotubes with an internal and external damping
No full textThe present works aims at modeling a viscoelastic nanobeam with simple boundary conditions at the two ends with the introduction of the Kelvin-Voigt viscoelasticity in a nonlocal strain gradient theory. The nanobeam lies on the visco-Pasternak matrix in which three characteristic parameters have a prominent role. A refined Timoshenko beam theory is here applied, which is only based on one unknown variable, in accordance with the Euler-Bernoulli theory, whereas the Hamilton’s principle is applied to derive the equations of motion. These are, in turn, solved for a carbon nanotube with some fixed material properties. An analytical method has been used to discretize the equations in the displacement field and time, while computing the time-response of the system. For validation purposes, the results based on the proposed formulation are successfully compared to several references. A final parametric investigation focuses on the sensitivity of the time-response of a nanotube under simple boundary conditions, to different parameters such as the length scale, the viscoelasticity coefficients or the nonlocal parameter
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