L-shaped Frame Research Articles

L 형상 용접 프레임의 피로 실험 및 시뮬레이션

A fatigue test on the steel welded L-shaped frame was conducted. The frame was consisted with carbon steel tube and reinforced bracket. The four type reinforced brackets were fabricated. They were two rectangular plate reinforced bracket, two sided pentagon plate reinforced bracket, triangular plate reinforced bracket and fully reinforced bracket. The fatigue test of frame was conducted with axial tension loading. The fatigue simulation of the steel welded L-shaped frame was also performed by the finite element method with code FEMFAT. The frame of fully reinforced bracket had the highest fatigue life and reinforced quality factor.

Spatial Rotation Kinematics and Flexural–Torsional Buckling

This paper aims to clarify the intricacies of spatial rotation kinematics as applied to three-dimensional (3D) stability analysis of metal framed structures with minimal mathematical abstraction. In particular, it discusses the ability of the kinematic relationships traditionally used for a spatial Euler–Bernoulli beam element, which are expressed in terms of transverse displacement derivatives, to detect the flexural–torsional instability of a cantilever and of an L-shaped frame. The distinction between transverse displacement derivatives and vectorial rotations is illustrated graphically. The paper also discusses the symmetry and asymmetry of tangent stiffness matrices derived for 3D beam elements, and the concepts of semitangential moments and semitangential rotations. Finally, the fact that the so-called vectorial rotations are independent mathematical variables are pointed out.

Geometrical rectification for images from a mobile large container inspection system

The mobile large container inspection system (MLCIS) is a more flexible X-ray radiographic system than conventional fixed systems. Ideally, the X-ray detectors should be arranged along an arc with the source at the center. However, detectors of the MLCIS are arranged in an L-shaped frame and result in a factual image which is distorted compared with the ideal image. We propose a geometrical rectification algorithm to convert the factual image to the ideal image. We choose the dimension ratios of identical objects shown on the factual and processed images with our algorithm as a measure, and the results is desirable.

An example of three-dimensional frame buckling

Physical test results are presented to resolve existing disagreements in the literature concerning the collapse load of an L-shaped frame which fails through torsional buckling. Available computer solutions for this problem are compared with particular attention given to the symmetry of the geometric stiffness matrix.

水平力を受ける H 形鋼柱の弾塑性曲げ捩れ座屈に関する実験的研究

The lateral-torsional buckling tests of H-shaped steel beam-columns subjected to axial force and horizontal load, are performed in the form of L-shaped frame consisting of an H-shaped column and a box beam to investigate the maximum strength and the deformation behavior. The effects of the axial force ratio, the slenderness ratio and the beam-to-column relative stiffness ratio on the lateral-torsional buckling load and the in-plane load-displacement relation are discussed by comparing the test results with the theoretical results. Summarizing the results of parametric tests, the following conclusions are derived; (1) The maximum strength of a beam-column obtained in the test is generally higher than the theoretical lateral-torsional buckling strength. Detailed investigation on this point is yet needed together with the post-buckling analysis. The effect of the lateral-torsional buckling clearly apperars in the grave strength reduction after the maximum strength is attained. (2) As to the beam-columns with the slenderness ratio larger than or equal to 120, the sudden decrease in the strength takes place right after the maximum strength is attained, and the rotation capacity scarcely expected in these beam-columns. (3) The decrease in the value of the beam to-column relative stiffness ratio reduces the rotation capacity in the range of relatively small slenderness ratio, because of the combined effect of the in-plane P・△ moment and lateral-torsional buckling deformation.

Additive Property of Modal Density for a Composite Structure

It has been postulated that the modal density for a composite structure is equivalent to sum of the modal densities of the idealized substructures. A demonstration of the validity of this postulate for a particular composite is given by analyzing a structure consisting of two beams joined at right angles to form an L-shaped frame. The frequency equation for the composite and its asymptotic representation are utilized to determine the cumulative number of modes for the structure as a function of frequency. Modal density is determined from a graphical presentation of these results and compared with the sum of the modal densities of the two substructures. Consistent agreement is obtained for all frequencies giving rise to the additive property of modal density for the structure analyzed. [Work supported by NASA.]

A simple apparatus for 16 mm. motion picture photography. Dermatologic subjects filmed by a new method.

The following information is presented for those who wish to make use of a simple, inexpensive method for photographing good quality 16 mm. color motion pictures for purposes of record, research, report, and teaching. The size of the desired photographic fields was first determined. From these specifications, one of us (J. P. G.) designed and constructed L-shaped frames. These outline the 2 sides of the field and are fastened at a fixed distance from the camera by a bar (Figure). The frames and bar provide a quick method for aligning the camera lens system at right angles to the surface of the skin. They also maintain the subject in focus and eliminate problems of centering. The frames give the physician-photographer a rapid and precise indication of the total field size that will be recorded. The aluminum frames may be autoclaved or immersed in cold sterilizing solution. (Alcohol is suggested rather

Ionization of air by beta rays from point sources.

With the rapidly increasing use of radioisotopes in research, therapy, and radiation protection studies, the problem of accurately determining the distribution of the energy imparted to chemical systems and to biological materials has greatly increased in importance. In the presence of beta radiation, the problem is simple only at points in a medium where the concentration is uniform over distances equal to or greater than the range of the emitted particles. Unfortunately this situation is of rare occurrence. In the more usual case, the problem requires: (a) evaluation of the dose as a function of the distance from a point source and (b) integration at a given point of the energy contributed by beta particles originating within the range of the particles. Since knowledge of (a) is required in order to proceed with (b), the investigations reported here were undertaken using air as a homogeneous medium. This choice allowed the use of large-dimensioned apparatus, with its relative ease of construction, and permits direct application to denser media of similar atomic numbers, such as tissues. Since the objective of these measurements was an accurate determination of the ionization distribution, the principal efforts were directed toward the demonstration that the observed ionization currents were due exclusively to the emitted particles in their undisturbed journey through the air and that all the effects due to solid scatterers or absorbers were properly accounted for. Owing to the special construction of one of our chambers, it was also necessary to prove that all the ions formed in the detecting volume were collected. Because of limitations of space, the many experiments performed will only be outlined here. The first step was to select a large room in which to make the measurements (Fig. 1). The source, S, was moved along the indicated diagonal of the room on which the ionization chamber, I. C., was placed. L represents the locus of points beyond which a p32 beta particle of maximum energy, elastically scattered, once in its path, could not possibly reach the center of the chamber. Thus it is beyond question that the size of the room was adequate. The possible effects of the earth's magnetic field (indicated by H in the figure) were eliminated by theoretical considerations and by experimental study. The source was supported by means of a large L-shaped frame dimensioned so that it subtended a solid angie at the source of less than 1.0 per cent, reducing scattering effects to negligible proportions. The source was suspended by means of thin (10 mil) wires and prevented from swinging by similar wires. It was mounted on a thin aluminum washer (Fig. 2) of 6 inches outside diameter and 2 inches inside diameter.