Papers by Keyword: Flexural Stiffness

Abstract: This paper deals with the flexural stiffness of sandwich structures based on fiberglass and polymeric foams. The influence of geometrical and material parameters on the resulting effective flexural stiffness of the sandwich structure is being studied experimentally, analytically and using FEM models. The effective elasticity module of the sandwich-structured element is being studied and it’s theoretical and model dependencies on the stiffness of the foam core are being investigated. These dependencies are then compared with experimentally observed values. This study shows it is necessary to pay special attention to the issue of flexural stiffness of walls when designing sandwich shell products in order to prevent possible failures in the practical applications of these types of structures.

Abstract: Within a composite material the materials shaped as fibres will take the most part of the tensions acting upon the matrix, which obviously presents less stiffness than the fibres. In order to accomplish the assessment of the behaviour for a polymeric composite part we deal with a lot more complicated issues than for the assessment of a simple metal part subjected to the same loads. The idea is to accomplish the balance of the individual layer stresses with the applied traction forces and bending moments and study the laminate as a whole.

Abstract: This research paper deals with an investigation of the mechanical properties of sandwich structures consisting of High Pressure Laminate facing layers (HPL) and various types of cores that are produced by vacuum bagging technology. These materials are connected with different adhesive layers and quality of connection to individual materials is evaluated. Moreover, prepared sandwich structures are tested in three-point bend. Based on the results, suitable combinations of individual materials are proposed for sandwich structures with regard to the quality of the adhesive bonding.

Abstract: The aim of this paper is to examine the natural frequencies of beams for different flexural stiffness, internal simple support locations and axial moving speed. In the present investigation, the linear transverse vibrations of an axially translating beam are considered based on Euler-Bernoulli model. The beam is passing through two frictionless guides and has an internal simple support between the guides. The governing differential equations of motion are derived using Hamiltons Principle for two regions of the beam. The method of multiple scales is employed to obtain approximate analytical solution. Some numerical calculations are conducted to present the effects of flexural rigidity, mean translating speed and different internal support locations on natural frequencies.

Abstract: This research paper deals with an investigation of the influence of honeycomb core compression on the mechanical properties of sandwich structures. These structures consist of prepreg facing layers and two different material types of honeycomb and are produced by modified compression molding called Crush-Core technology. Produced structures are mechanically tested in three-point bending test and subjected to low-velocity impact and Charpy impact test.

Abstract: This study examines the effect of different variables of Profiled Steel Sheet (PSS) on various aspects of Profiled Steel Sheet Dry Board (PSSDB) system. PSS is an important component of PSSDB. The sensitivity of PSS variables at the 70% to 140% of Peva45 dimensions, the profiled steel sheet at local markets, to the cross-sectional area of PSS, the ultimate load carrying capacity, and the flexural stiffness of the PSSDB system is analysed. Results are shown in charts, and the most effective variables are determined. The dominant variables are found by saving computational time in the optimization of PSS in the PSSDB system.

Abstract: In a number of previous publications, results were reported for a series of extensive and carefully conducted tests on large scale reinforced concrete (R.C.) beams with various extents of loss of concrete cover and exposure of main reinforcement along their spans, with such areas of simulated damage being located within their regions which are dominated by either shear or flexure. These tests on R.C. beams made with normal strength concrete have covered a wide range of first order beam design parameters, with their results used to verify the generality of various theoretical models. In the present paper, much attention will be devoted to various structural characteristics (such as ultimate strength, flexural stiffness, etc.) of similar damaged R.C. beams with the proviso that, instead of the previously used normal strength concrete, the beams are made with high strength concrete. No such results (for high strength R.C. beams) have previously been reported in the public domain.

Abstract: Based on appropriate numerical constitutive model of lightweight aggregate concrete filled steel tubes (LCFST), layered method was adopted to predict the complete moment-curvature curves of LCFST composite section subjected to pure bending. A FORTRAN program for the moment-curvature curves was developed. Applying the layered method, the influences of the significant parameters, such as steel ratio, yield strength of steel and strength of lightweight aggregate concrete on the moment-curvature curves of the composite section subjected to pure bending were discussed. The practical composite flexural stiffness, ultimate moment and practical moment- curvature relationship of LCFST composite section were presented. The predicted results of both layered method and practical moment-curvature relationships of LCFST composite section are in good agreement with the test results from reference. Compared with the layered method, practical calculate method could remove the step of composite section layered and improve the calculation speed while achieving similar results.

Abstract: Joint’s stiffness has important influence on stability bearing capacity of large-span spatial reticulated shell. The welded hollow spherical joint with rib stiffeners is a type of joint applied widely on large-span spatial reticulated shell. In this paper, the axial flexibility and flexural stiffness of welded hollow spherical joint with different rib stiffeners are analyzed with the FEM software ANSYS, compared with the non-rib hollow spherical joint’s stiffness, then the calculation formulas of the axial flexibility and flexural stiffness under different rib stiffeners are given through regression analysis. Some important conclusions were obtained, which can provide theoretical foundation for the stability bearing capacity analysis considering joint’s stiffness and can be applied on practical design..

Abstract: Three-bending experiments were performed on RC beams strengthened with prestressed CFRP under static and cycle loading. Prestressed CFRP obviously increases the load-carrying capacity and fatigue life of strengthened RC beam. And it greatly increases the flexural stiffness of strengthened beam. The failure modes of the beams go through concrete cracking, CFRP debonding from concrete and beam fractured. The vertical flexibility history at midspan is decomposed into three stages. And then fatigue damage is defined by flexural stiffness and its evolvement shows three stages of nucleation, growth and mutation.