Bending Moment In Plane Research Articles

Finite element modeling of bolted steel connections designed by double channel

In this paper an investigation based on tests and a finite element modeling of the behaviour of a double channel beam-to-column connection subjected to in plane bending moment and shear is presented. The results of tests conducted at the Istanbul Technical University were briefly described and presented for comparison. Simulation of the tests was carried out by means of a nonlinear finite element software ANSYS 5.5.1 version. Wide flange I section column, double channel beam section, bolt components were represented in three-dimensional forms and material nonlinearity with strain hardening were taken into account. Boundary conditions between the bolts, double channels and the column section were modeled with contact elements which are capable of representing the actual behaviour. The results of finite element model are compared with that of the reference tests.

INVESTIGATION OF THIN-WALLED COLUMN WITH VARIABLE I-SECTION STABILITY USING FINITE ELEMENT METHOD/PLONASIENĖS KINTAMOJO DVITĖJO SKERSPJŪVIO KOLONOS STABILUMO TYRIMAS BAIGTINIŲ ELEMENTŲ METODU

Thin-walled structures are widely used in building construction. Stability analysis [1–10] is of major importance to the design of thin-walled structures. This paper deals with the stability analysis of the thin-walled tapered column [11–18]. The aim is to investigate the influence of variation of the web height on the stability of column and combined action of axial force and plane bending moment. Critical state is defined by stability surface obtained by numerical experiments using the finite element method. Mathematical model of the linearised stability problem is presented as algebraic eigenvalue problem (1), where eigenvalues express the critical loading factor (2). Analytical solutions are known for particular cases of separate loading (4), (5). In this paper, the column with variable I-section is presented as assemblage of beam elements with constant section. Thin-walled beam element has 14 degrees of freedom (Fig 1), including linear displacements, rotations and warping displacements. Variation of cross-section of the column (Fig 2) is defined by relative height of web alb, were a and b are the height at the ends of column. Critical state is described by stability surface obtained using numerical experiments. Stability surface presents in the space of relative variation of height a/b, relative length and relative critical force and bending moment . Variation of section influences the critical bending moment only. The influence of finite element number on the with different relative height of web a/b is investigated numerically (Fig 3), and its variation of stability surface is presented in Fig 4. The numerical results show that variation of critical moment to relative web height a/b is linear (Fig 5). The shapes of buckling modes are presented in Fig 6. Variation of stability surface to relative length (6) is presented in Figs 7 and 8 and expressed by the simple expression (6) constructed on the basis of numerical experiments. Finally, the stability model (1) is compared with nonlinear calculations performed using program ANSYS [19] and shell finite elements (Figs 9 and 10).

INVESTIGATION OF THIN-WALLED COLUMN WITH VARIABLE I-SECTION STABILITY USING FINITE ELEMENT METHOD

Summary Thin-walled structures are widely used in building construction. Stability analysis [1–10] is of major importance to the design of thin-walled structures. This paper deals with the stability analysis of the thin-walled tapered column [11–18]. The aim is to investigate the influence of variation of the web height on the stability of column and combined action of axial force and plane bending moment. Critical state is defined by stability surface obtained by numerical experiments using the finite element method. Mathematical model of the linearised stability problem is presented as algebraic eigenvalue problem (1), where eigenvalues express the critical loading factor (2). Analytical solutions are known for particular cases of separate loading (4), (5). In this paper, the column with variable I-section is presented as assemblage of beam elements with constant section. Thin-walled beam element has 14 degrees of freedom (Fig 1), including linear displacements, rotations and warping displacements. Vari...

Combined intramedullary kirschner wire and intra-osseous wire loop for fixation of finger fractures

An intramedullary Kirschner wire was combined with an intra-osseous wire loop for fixing finger fractures. The mechanical stability of this technique to resist a bending moment in the sagittal plane was compared with four other conventional methods: single loop, loop and an oblique Kirschner wire, crossed Kirschner wires and dorsal plating. It was found that when the applied force was small, the technique was much more stable than the crossed Kirschner wires and was similar to the others. The ability to withstand mechanical failure was much better than most of the methods except the dorsal plate. This technique is recommended for replantations, transverse fractures and short oblique fractures with little comminution.

SCF Equations for T/Y and K Square-to-Round Tubular Joint

A parametric stress analysis of T/Y and K square-to-round tubular joints subjected to axial loads and in-plane and out-of-plane bending moments has been performed with the finite-element technique. Twenty-two and 26 sets of geometric parameters were used for the study of T/Y and K joints, respectively. This study was carried out to provide a sound basis for using square tubular sections in the design of offshore structures. The results of this analysis are presented as a set of 21 equations expressing the stress concentration factor (SCF) as a function of the relevant geometric parameters for various loading conditions. A comparison is made between the results obtained for square-to-round tubular joints and those obtained for round-to-round tubular joints and for square-to-square tubular joints. In general, the SCF's obtained from square-to-round tubular joints are closest to those of the corresponding round-to-round tubular joints than those of the corresponding square-to-square tubular joints.

Querstabilisierung des fixateur interne an der wirbelsäule

The "Internal Fixator" for stabilizing the dorso-lumbar spine represents an effective and meanwhile established device to neutralize flexion-bending and sagittal shearing forces. Because of the possible movement of the Schanz' screws in the bone and within the connection clamps, this device does not withstand torsional and frontal plane shearing forces after postinjury or postlaminectomy instability. Therefore, a cross-link device, adaptable to the "Internal Fixator" has been developed. Biomechanical testing against torsion and frontal plane bending moments have shown very low stability resulting in lateral displacement of the fixation device without cross-linking. The diagonal bracing with two wire cerclages does not significantly increase the stability. The recently developed cantilever cross-link device completes the two longitudinal bars to a frame construction and increases therefore the torsional and frontal plane stability for over 70%. This supplementary device is easy to apply to the "Internal Fixator" and has been successful in clinical practise.

Load-bearing role of facets in a lumbar segment under sagittal plane loadings

In the present work, the load-bearing role of the facet joints in a lumbar I 2–3 segment is quantitatively determined by means of a three dimensional nonlinear finite element program. The analysis accounts for both material and geometric nonlinearities and treats the facet articulation as a nonlinear moving contact problem. The disc nucleus is considered as an inviscid incompressible fluid and the annulus as a composite of collagenous fibres embedded in a matrix of ground substance. The spinal ligaments are modelled as a collection of nonlinear axial elements. The loadings consist of axial compression and sagittal plane shears and bending moments, acting alone or combined. The results show that in pure compression, the external axial force is transmitted primarily by the intervertebral disc. The facet joints carry only a small percentage of the force. However, the facet joints carry large forces in extension, whereas in small flexion they carry none. Addition of compression tends to increase these contact forces in extension while it has no effect on them in flexion. In extension, the forces on the facet joints are transmitted by both the articular surfaces and the capsular ligaments. Although in small flexion the facets carry no load, large contact forces are predicted to develop as the segment is flexed beyond 7–8°. These forces are of the same magnitude as those computed under large extension rotation and are oriented nearly in the horizontal plane with negligible component in the axial direction. The horizontal components of the contact forces generated during articulation are often larger than the axial components which directly resist the applied compressive force. The axial components of the contact forces, therefore, grossly underestimate the total forces acting on the facets. The transfer of forces from one facet to the adjacent one occurs through distinct areas in flexion and in extension loadings. That is, on the superior articular surface, the contact area shifts from the upper tip in large flexion to the lower margin in extension. On the inferior articular surface, the contact area shifts from the upper and central regions in large flexion to the lower tip in extension.

Stress analysis of L shape joints and evaluation of joint strength.

In this paper, L shape joints, which are subjected to a bending moment in plane, are analyzed numerically by the finite element method proposed in the previous paper. The resultant shear stress at the adhesive layer concentrates at the boundaries between the adherend plates. The values increase with the decrease of the ratio h/t (h : the thickness of adhesive layer and t : the thickness of adherend plates). These results are compared with Yamaguchi's theory proposed previously. It is obvious that he theory is too approximate. On the other hand, a practical L shape joint test, of which the adherend is an aluminum plate and the adhesive is an epoxy resin bond, is performed. The joint strength are also compared with the values estimated by using the finite element method and the corresponding fracture criteria.

Further Studies of the Strength of Beam-Columns

Two basically different loading conditions were examined, and results are presented in interaction curve form; it has been assumed that member is of asrolled wide flange shape, subjected to bending moments in plane of its web; failure by excessive bending in plane of applied moments; possibility of unwinding in case in which imposed moments result in double curvature type of deformation.

Strength of Very Slender Beams

Response to lateral loads and twisting couples is affected by presence of bending moments in plane of major stiffness; resulting nonlinear theory discussed; inclusion of nonlinear terms in strain displacement relations corresponds generally to stiffening of structure as compared with familiar linear theory; theory presented is corroborated experimentally with fair degree of accuracy.

The Strength of Very Slender Beams

Response to lateral loads and twisting couples is affected by presence of bending moments in plane of major stiffness; resulting nonlinear theory discussed; inclusion of nonlinear terms in strain displacement relations corresponds generally to stiffening of structure as compared with familiar linear theory; theory presented is corroborated experimentally with fair degree of accuracy.

Rotor Bending Moments in Plane of Flapping

The present paper, a problem in autogiro rotor stress analysis, can be outlined as follows: 1. Calculation of the characteristics of a typical autogiro employed for illustrative purposes. 2. Derivation of formulas for bending moments in the plane of flapping taking into account the effects of the weight of the blade, centrifugal force, inertia forces in flapping and aerodynamic thrust. 3. Examination of the effect of the azimuth angle ^ on bending moments at a given point on the blade. 4. Effect of variations in /*, the tip speed ratio, on the bending moment a t a given point on the blade. 5. Examination of the effect of the ratio r/R on bending moments. 6. Formulas for the centrifugal relief of bending moments. 7. Comparison of bending moments obtained by the above methods with the bending moments obtained by the use of empirical formulas available hitherto. Certain simplifications have been employed. These are: (a) Only the first harmonic of the flapping motion is considered. (b) Terms of a higher order than A* are neglected. (c) The flow through the rotor disk is considered uniform. (d) Mass distribution along the span of the blade is uniform. (e) The product EI is uniform along the span of the blade. (f) Stalling effects that may occur at portions of the blade are neglected. (g) Periodic twisting of the blade is not taken into account. The underlying aerodynamic theory is well known to those interested in the autogiro and no presentation of such theory is made in the present paper.