• Computers and Concrete
• /
• 제30권5호
• /
• pp.311-321
• /
• 2022

The interfacial bond strength of partially encased composite (PEC) structure tends to 0, therefore, the cast-in-place concrete theoretically cannot embody better composite effect than the fabricated structure. A total of 12 specimens were designed and experimented to investigate the energy dissipation and damage of fabricated PEC beam through unidirectional cyclic loading test. Because the concrete on both sides of the web was relatively independent, some specimens showed obvious asymmetric concrete damage, which led to specimens bearing torsion effect at the later stage of loading. Based on the concept of the ideal elastoplastic model of uniaxial tensile steel and the principle of equivalent energy dissipation, the energy dissipation ductility coefficient is proposed, which can simultaneously reflect the deformability and bearing capacity. In view of the whole deformation of the beam, the calculation formula of energy dissipation is put forward, and the energy dissipation and its proportion of shear-bending region and pure bending region are calculated respectively. The energy dissipation efficiency of the pure bending region is significantly higher than that of the shear-bending region. The setting of the screw arbors is conducive to improving the energy dissipation capacity of the specimens. Under the condition of setting the screw arbors and meeting the reasonable shear span ratio, reducing the concrete pouring thickness can lighten the deadweight of the component and improve the comprehensive benefit, and will not have an adverse impact on the energy dissipation capacity of the beam. A damage model is proposed to quantify the damage changes of PEC beams under cyclic load, which can accurately reflect the load damage and deformation damage.

• Structural Engineering and Mechanics
• /
• 제52권4호
• /
• pp.843-855
• /
• 2014

Concrete infill and reinforcement are one of the most well-known strengthening methods of structural elements. This study investigated flexural performance of concrete infill composite PHC pile (ICP pile) reinforced by infill concrete and longitudinal rebars in hollow PHC pile. A total four series of pile specimens were tested by four points bending method under simply supported conditions and investigated bending moment experimentally and analytically. From the test results, it was found that although reinforcement of infilled concrete on the pure bending moment of PHC pile was negligible, reinforcement of PHC pile using infilled concrete and longitudinal rebars increase the maximum bending moment with range from 1.95 to 2.31 times than that of conventional PHC pile. The error of bending moment between experimental results and predicted results by nonlinear sectional analysis on the basis of the conventional layered sectional approach was in the range of -2.54 % to 2.80 %. The axial compression and moment interaction analysis for ICP piles shows more significant strengthening effects of infilled concrete and longitudinal rebars.

• 한국재료학회지
• /
• 제28권11호
• /
• pp.671-679
• /
• 2018

Finite element analyses are carried out to understand the piezoelectric behaviors of ZnO nanowires. Three different types of ZnO nanowires, with aspect ratios of 1:2. 1:31, and 1:57, are analyzed for uniaxial compression, pure bending, and buckling. Under the uniaxial compression with a strain of $1.0{\times}10^{-4}$ as the reference state, it is predicted that all three types of nanowires develop the same magnitude of the piezoelectric fields, which suggests that longer nanowires exhibit higher piezoelectric potential. However, this prediction is not in agreement with the experimental results previously reported in the literature. Such discrepancy is understood when the piezoelectric behaviors under bending and buckling are considered. When only the strain field due to bending is present in bending or buckling, the antisymmetric nature of the through-thickness stain distribution indicates that two piezoelectric fields, the same in magnitude and opposite in sign, develop along the thickness direction, which cancels each other out, resulting in a zero net piezoelectric field. Once additional strain contribution due to axial deformation is superposed on the bending, such field cancelling is compensated for due to the axial component of the piezoelectric field. Such numerical predictions seem to explain the reported experimental results while providing a guideline for the design of nanowire-based piezoelectric devices.

• 소성∙가공
• /
• 제14권4호
• /
• pp.375-383
• /
• 2005

The shear spinning process, where the plastic deformation zone is localized in a very small portion of the workpiece, shows a promise for increasingly broader application to the production of axially symmetric parts. In this paper, the three components of the working force are calculated by a newly proposed deformation model in which the spinning process is understood as shearing deformation after uniaxial yielding by bending, and shear stress, $\tau_{rz}$, becomes k, yield limit in pure shear, in the deformation zone. The tangential force are first calculated and the feed force and the normal force are obtained by the assumption of uniform distribution of roller pressure on the contact surface. The optimum contact area is obtained by minimizing the bending energy required to get the assumed deformation of the blank. The calculated forces are compared with experimental results. A comparison shows that theoretical prediction is reasonably in good agreement with experimental results

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 1998년도 가을 학술발표회 논문집
• /
• pp.208-215
• /
• 1998

A stability problems of isotropic shells under pure bending is investigated based on the classical shells theory. The governing equations of stability problem presented by Donnell and Love, are developed and the solutions for the cylindrical shells are obtained by using Galerkin method. Bending moment is applied at the ends of the cylindrical shell as a from of distributed load in the shape of sine curve. For the isotropic materials, the result of the general purpose structural analysis program based on the finite element method are compared with the critical moment obtained from the classical shell theories. The critical loads for the cylindrical shells with various geometry can not be evaluated with a simple equation. However, accurate solutions for the stability problems of cylindrical shells can be obtained through the equilibrium equation developed in the study.

• Structural Engineering and Mechanics
• /
• 제58권4호
• /
• pp.641-659
• /
• 2016

This paper deals with the pure bending of incompressible elastic perfectly plastic two-layer sheets under plane strain conditions at large strains. Each layer is classified by its yield stress, shear modulus of elasticity and its initial percentage thickness in relation to the whole sheet. The solution found is semi-analytic. In particular, a numerical technique is only necessary to solve transcendental equations. The general solution is cumbersome because different analytic expressions for the radial and circumferential stresses should be adopted in different regions of the whole sheet. In particular, there are several alternative ways a plastic region (or plastic regions) can propagate. However, for any given set of material and process parameters the solution to the problem consists of a sequence of rather simple analytic expressions connected by transcendental equations. The general solution is illustrated by a simple example.

• Journal of Mechanical Science and Technology
• /
• 제20권6호
• /
• pp.806-818
• /
• 2006

The shear spinning process, where the plastic deformation zone is localized in a very small portion of the workpiece, shows a promise for increasingly broader application to the production of axially symmetric parts. In this paper, the three components of working force are calculated by the newly proposed deformation model in which the spinning process is understood as shearing deformation after uniaxial yielding by bending, and shear stress, $\tau_{rz}$ becomes $\kappa$, yield limit in pure shear, in the deformation zone. The tangential forces are first calculated and the feed forces and the normal forces are obtained by the assumption of uniform distribution of roller pressure on the contact surface. The optimum contact area is obtained by minimizing the bending energy required to get the assumed deformation of the blank. The calculated forces are compared with experimental results. A comparison shows that theoretical prediction is reasonably in good agreement with experimental results.

• 한국염색가공학회지
• /
• 제12권6호
• /
• pp.337-343
• /
• 2000

In this study, the five harness satins are weaved in rapier loom and air-jet loom each using the pure wool Nm 2/72, also the physical characteristics of fabrics that are produced in these weaving machinery in same condition are measured by using the KES-FB system. The results of analysis and comparison on each fabric are presented by classifying items, that is to say, the tensile, bending properties. The results we as follows ; The extensibility of grey fabric woven by rapier in the weft direction is larger than that by air-jet loom. The variation of bending property of grey fabric woven by rapier in the weft direction is more irregular than that by air-jet loom. However, these properties are similar both rapier and air jet fabrics.

• 한국전산구조공학회논문집
• /
• 제14권4호
• /
• pp.423-434
• /
• 2001

본 논문은 도로의 선형이 곡선일때, 곡선상에 설치되는 곡선교를 해석함에 있어 에너지법에 기초하여 휨과 순수비틂 효과를 고려한 탄성방정식을 이용한다. 이 탄성방정식은 부정정 구조인 연속곡선박스거더의 정역학적 부정정력을 최소 일의 원리를 적용하여 구한다. 곡선박스거더에 수직단위하중과 단위토크를 작용시켜 전단력, 휨모멘트, 순수비틂모멘트, 그리고 처짐과 회전각에 대한 영향선을 구하며, 실제 하중이 작용할 때 곡선박스거더의 부재력을 구할 수 있도록 하였다.

• 대한조선학회지
• /
• 제4권1호
• /
• pp.55-58
• /
• 1967

It is investigated that in what shape the stress concentration factor of a notched strip under pure bending changes due to unsymmetrically varying notch angle. Four models made of CR-39, having parameters of r/d-0.225, h/r=4; r/d=0.225, h/r=2; r/d=0.4, h/r=4 and r/d=0.4, h/r=2 respectively as shown in Fig.1, Fig.2 and Table are tested with the use of polariscope. For each model, notch angle is unsymmetrically varied from $0^{\circ}$ to $180^{\circ}$ at intervals of $15^{\circ}$ as shown in Fig. 1 and Fig. 2. The results of this experiment are Fig. 7 and Fig. 8 and the following are deduced. As notch angle increases 1) from $0^{\circ}$ to $50^{\circ}$, the decrement of concentration factor is slight. 2) from $50^{\circ}$ to 90, the decrement of concentration factor is a little steeper. 3) from $30^{\circ}$ to $140^{\circ}$, the decrement of concentration factor is slight. 4) from $140^{\circ}$ to $180^{\circ}$, the decrement is very steep with an abrupt with an abrupt change in the neighborhood of $140^{\circ}$.