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Free vibration and Ljapounov stability of compressed open thin-walled beams with a cross-section reduction are studied by a in-house finite differences numerical code, based on a refined direct beam model and allowing for investigating elastic stability of non-trivial equilibrium paths in a dynamic setting. The benchmark is a beam with doubly symmetric cross-section and non-zero warping rigidity, under free, semi-, and fully restrained warping at its ends. In all cases, the results of the direct model are compared to finite element and/or experimental ones. The reduction in the cross-section rigidity induces a weakening that may model a local damage; thus, the present investigation may be useful with an outlook to damage monitoring and identification. [ABSTRACT FROM AUTHOR]

The problem of determining the stress-strain state of the rod with non-circular cross-section in torsion considering creep was solved. The solution is based on the hypothesis of Saint-Venant used in the theory of elastic torsion of rods. In contrast to the elastic problem, warping function in creep is not a harmonic function. The problem has reduced to the Poisson differential equation for the stress function. The solution is made numerically by using the finite difference method. An example of the calculation for the polymeric rod from recycled PVC is given. It was found that the shear stresses during creep virtually unchanged, and the relative twist angle increased by 14%. [ABSTRACT FROM AUTHOR]

Structures of the open thin-walled profile are usually designed so to avoid twisting the individual elements. However, for some systems it is impossible to completely prevent twisting due to the torsion of a thin-walled open section, sectional warping due to tightness, additional sectoral stresses. The torsional stiffness of the thin-walled open section of the rod is much higher than their pure torsion rigidity. The structural analysis of the open thin-walled profile can be performed using a finite element shell. This requires careful selection and design of the grid partition and greatly increases the number of nodes and elements in the calculation scheme. Thin-walled rod finite elements can be used to calculate the complex spatial structures of a thin-walled open section with the account of clean and restrained torsion. [ABSTRACT FROM AUTHOR]

In this study, free vibration analysis of thin-walled channel section beam including warping effects has been carried out using Finite element method (FEM) and compared with experimentally measured results. Results reveal that natural frequencies of the system decrease on exclusion of warping in the analysis. Also, it has been observed that the difference between higher mode shapes were significantly high when theoretically obtained mode shapes considering warping and without warping were compared. Thereafter, the Modal Assurance Criterion (MAC) plot is presented to show the difference between the mode shapes with and without consideration of warping stiffness. [ABSTRACT FROM AUTHOR]

Fused Deposition Modeling (FDM) is the most used 3D printing technology. In this technology, 3D pieces are built warming and extruding thermoplastic through a nozzle. When the thermoplastic gets cold, internal stresses may generate deformations, mainly in corners. In this paper we describe a method for reduce these deformations (called warping), splitting pieces in hexagonal or squared bricks spatially locked. We have developed and tested an application that calculates the necessary GCODE to build the bricking piece directly, and we have measured a significant reduction in warp deformations. [ABSTRACT FROM AUTHOR]

Abstract: Stress state of structural member has a significant effect on its dimensions and must be included in the design of member. The proposed paper is directed to distribution of normal stress in thin-walled members with open cross-section due to special case of temperature load. The paper concentrates on analysis of stress state of some types of thin-walled members; data are used in setting both of axial forces, bending moments a and of bimoments too. [Copyright &y& Elsevier]

Abstract: Composite steel-concrete slabs that have integral steel shuttering at the soffit of a reinforced concrete slab are commonplace in building infrastructure. Inevitable shrinkage of the concrete represents an indirect (or non-mechanical) strain that results in deformations of the composite slab, resulting in long-term effects in which creep of the concrete also plays a role. Because the impervious steel sheeting prevents moisture egress at the slab soffit whereas at the top of the slab such moisture egress can occur, there is a variation of the shrinkage strain through the depth of the slab, resulting in warping-type deformations. In addition, the composite action between the steel and concrete results in partial shear interaction between these elements, and this interacts with the shrinkage response. Surprisingly little appears in the published literature on rational modelling of the behaviour of composite slabs incorporating partial interaction that are subjected to shrinkage straining, despite its practical importance and significance. Based on fundamental principles of mechanics, a theoretical model of this shrinkage behaviour that includes partial interaction is developed, and prescriptive equations are derived. These may be used to assess the deflections and stresses in the concrete due to restrained shrinkage which may lead to cracking of the slab. It is also shown that the two effects of partial interaction and shrinkage straining counteract each other when slab deflections are considered. [Copyright &y& Elsevier]