Bending and free vibration of functionally graded beams using various higher-order shear deformation beam theories

In this paper, various higher-order shear deformation beam theories for bending and free vibration of functionally graded beams are developed. The developed theories account for higher-order variation of transverse shear strain through the depth of the beam, and satisfy the stress-free boundary conditions on the top and bottom surfaces of the beam. A shear correction factor, therefore, is not required. In addition, these theories have strong similarities with Euler–Bernoulli beam theory in some aspects such as equations of motion, boundary conditions, and stress resultant expressions. The material properties of the functionally graded beam are assumed to vary according to power law distribution of the volume fraction of the constituents. Equations of motion and boundary conditions are derived from Hamilton's principle. Analytical solutions are presented, and the obtained results are compared with the existing solutions to verify the validity of the developed theories. Finally, the influences of power law index and shear deformation on the bending and free vibration responses of functionally graded beams are investigated

DNA damage signaling in response to double-strand breaks during mitosis

Dividing cells can sense DNA damage and initiate a primary response, but repair isn’t completed until the cells enter G1

Modeling of composite and sandwich beams with a generic cross-section using a variable separation method

International audienceIn this work, the modeling of laminated composite and sandwich beams with a generic cross-section is performed through a variable separation approach. For this purpose, the displacement is approximated as a sum of sepa-rated functions of the cross-section coordinates y, z and the axial coordinate x. This choice yields to a non-linear problem that can be solved by an iterative process. This latter consists of solving a 2D and 1D Finite Element problem successively at each iteration.Numerical examples involving several representative sandwich and laminated beams are addressed to show the accuracy of the present method. It is shown that it can provide 3D results and capture local effects for various types of cross-sectio

Static and free vibration of axially loaded functionally graded beams based on the first-order shear deformation theory

The first-order shear deformation beam theory for static and free vibration of axially loaded rectangular functionally graded beams is developed. In this theory, the improved transverse shear stiffness is derived from the in-plane stress and equilibrium equation and thus, associated shear correction factor is then obtained analytically. Equations of motion are derived from the Hamilton’s principle. Analytical solutions are presented for simply-supported functionally graded beams. The obtained results are compared with the existing solutions to verify the validity of the developed theory. Effects of the power-law index, material contrast and Poisson’s ratio on the displacements, natural frequencies, buckling loads and load–frequency curves as well as corresponding mode shapes are investigated

Calculation of the work of adhesion of polyisoprene on graphite by molecular dynamics simulations

Elastomeric compounds are reinforced with fillers such as carbon-black and silica to improve mechanical, dynamical, and tribological properties. The stability and physical properties of these materials are dominated by the intermolecular interactions occurring at the polymer/particles interface that determine the magnitude of the polymer/particles adhesion. Using molecular dynamics simulations, in this work, we evaluate the solid–liquid interfacial tension and the corresponding work of adhesion for a system composed of graphite/Polyisoprene 100% cis-1,4 within a range of molar masses and temperatures. We employ a simulation strategy for estimating the surface tension of fluid/vacuum and fluid/solid interfaces that use directly the local stress fields in the Irving–Kirkwood formalism. Using such procedure, we decompose the stress field into the individual components of the stress tensor and correlate them with the values of the work of adhesion in the different systems analyzed

Provinciality and the Art World: The Midland Group 1961- 1977

This paper takes as its focus the Midland Group Gallery in order to first, make a case for the consideration of the geographies of art galleries. Second, highlight the importance of galleries in the context of cultural geographies of the sixties. Third, discuss the role of provinciality in the operation of art worlds. In so doing it explicates one set of geographies surrounding the gallery – those of the local, regional and international networks that connected to produce art works and art space. It reveals how the interactions between places and practices outside of metropolitan and regional hierarchies provides a more nuanced insight into how art worlds operated during the sixties, a period of growing internationalism of art, and how contested definitions of the provincial played an integral role in this. The paper charts the operations of the Midland Group Gallery and the spaces that it occupied to demonstrate how it was representative of a post-war discourse of provincialism and a corresponding re-evaluation of regional cultural activity

Static and vibration analysis of functionally graded beams using refined shear deformation theory

Static and vibration analysis of functionally graded beams using refined shear deformation theory is presented. The developed theory, which does not require shear correction factor, accounts for shear deformation effect and coupling coming from the material anisotropy. Governing equations of motion are derived from the Hamilton's principle. The resulting coupling is referred to as triply coupled axial-flexural response. A two-noded Hermite-cubic element with five degree-of-freedom per node is developed to solve the problem. Numerical results are obtained for functionally graded beams with simply-supported, cantilever-free and clamped-clamped boundary conditions to investigate effects of the power-law exponent and modulus ratio on the displacements, natural frequencies and corresponding mode shapes

Management and competitiveness: a case of the audiovisual industry in Argentina

La importancia de las economías creativas a nivel mundial es el punto de partida de este análisis realizado, que valora la posición destacada de dicha industria en el desarrollo económico regional y nacional, en particular el sector audiovisual. Se estudió y destacó, como ejemplo de innovación y competitividad, a la Asociación Civil Film Andes que se constituye desde hace 3 años como un clúster de empresas productoras audiovisuales y asociadas en la región. Objetivos: se plantearon como objetivos de la investigación analizar la historia y desarrollo de Film Andes como asociación y clúster, revisar el impacto de la economía creativa en el desarrollo económico general y en la diversificación de la matriz productiva de la provincia, presentar conclusiones sobre la madurez asociativa de los miembros de Film Andes, e indagar sobre objetivos futuros y potencial crecimiento del clúster

Defect Coverage after Forequarter Amputation—A Systematic Review Assessing Different Surgical Approaches

Autologous fillet flaps are a common reconstructive option for large defects after forequarter amputation (FQA) due to advanced local malignancy or trauma. The inclusion of osseous structures into these has several advantages. This article therefore systematically reviews reconstructive options after FQA, using osteomusculocutaneous fillet flaps, with emphasis on personalized surgical technique and outcome. Additionally, we report on a case with an alternative surgical technique, which included targeted muscle reinnervation (TMR) of the flap. Our literature search was conducted in the PubMed and Cochrane databases. Studies that were identified were thoroughly scrutinized with regard to relevance, resulting in the inclusion of four studies (10 cases). FQA was predominantly a consequence of local malignancy. For vascular supply, the brachial artery was predominantly anastomosed to the subclavian artery and the brachial or cephalic vein to the subclavian or external jugular vein. Furthermore, we report on a case of a large osteosarcoma of the humerus. Extended FQA required the use of the forearm for defect coverage and shoulder contour reconstruction. Moreover, we performed TMR. Follow-up showed a satisfactory result and no phantom limb pain. In case of the need for free flap reconstruction after FQA, this review demonstrates the safety and advantage of osteomusculocutaneous fillet flaps. If the inclusion of the elbow joint into the flap is not possible, we recommend the use of the forearm, as described. Additionally, we advocate for the additional implementation of TMR, as it can be performed quickly and is likely to reduce phantom limb and neuroma pain