Effect of details of vertical stiffener on fatigue behavior of welding plate beams

The design of the vertical stiffener details is important in the anti-fa- tigue design of the welded steel plate beams.There still exist different opinions on the selection of the design parameters and the effect of the shear stress.In the present study,the effects of the welding process(semi-automatic welding, manual welding)and the connecting location of vertical stiffener(welded to the web or to the flange)on the fatigue behaviour in the regions subjected to the pure bending and subjected to the bending and shearing are investigated by test- ing the simulation beams of large scale.The analysis of the fatigue test results shows that the normal bending stress is the governing factor to the fatigue strength.

APPLICATIONS OF WAVELET GALERKIN FEM TO BENDING OF BEAM AND PLATE STRUCTURES

In this paper, an approach is proposed for taking calculations of high order differentials of scaling functions in wavelet theory in order to apply the wavelet Galerkin FEM to numerical analysis of those boundary-value problems with order higher than 2. After that, it is realized that the wavelet Galerkin FEM is used to solve mechanical problems such as bending of beams and plates. The numerical results show that this method has good precision.

Analysis and seismic tests of composite shear walls with CFST columns and steel plate deep beams

A composite shear wall concept based on concrete filled steel tube （CFST） columns and steel plate （SP） deep beams is proposed and examined in this study. The new wall is composed of three different energy dissipation elements： CFST columns; SP deep beams; and reinforced concrete （RC） strips. The RC strips are intended to allow the core structural elements - the CFST columns and SP deep beams - to work as a single structure to consume energy. Six specimens of different configurations were tested under cyclic loading. The resulting data are analyzed herein. In addition, numerical simulations of the stress and damage processes for each specimen were carried out, and simulations were completed for a range of location and span-height ratio variations for the SP beams. The simulations show good agreement with the test results. The core structure exhibits a ductile yielding mechanism characteristic of strong column-weak beam structures, hysteretic curves are plump and the composite shear wall exhibits several seismic defense lines. The deformation of the shear wall specimens with encased CFST column and SP deep beam design appears to be closer to that of entire shear walls. Establishing optimal design parameters for the configuration of SP deep beams is pivotal to the best seismic behavior of the wall. The new composite shear wall is therefore suitable for use in the seismic design of building structures.

PERTURBATION ANALYSIS FOR MAGNETO-PLASTIC INSTABILITY OF FERROMAGNETIC BEAM-PLATES WITH GEOMETRIC IMPERFECTION

The magneto-plastic instability of a ferromagnetic beam-type plate with simple supports and small initial imperfection is analytically investigated in this paper for that the plastic deformation of the plate with a linear-strain hardening relation is considered when the plate is located in a strong uniformly distributed magnetic ?eld. After the distribution of magnetic ?elds related to the de?ected con?guration of plate is imaginably divided into two parts, i.e., one is related to the ?at plate and the other dependent on the perturbation of magnetic ?elds for which the plate con?guration changes from the ?at into the deformed state, the perturbation technique is employed to analyze the distribution of the perturbation magnetic ?elds in and out-of the magnetic medium of the ferromagnetic structure in a transverse magnetic ?eld, which leads to some analytical formulae/solutions for the magnetic ?elds and the resulting magnetic force exerted on the plate. Based on them, the magneto-plastic buckling and snapping of the plate in a transverse magnetic ?eld is discussed, and the critical magnetic ?eld is analytically formulated in terms of the parameters of geometry and material of the plate employed by solving the governing equation of the magneto-plastic plate in the applied magnetic ?eld. Further, the sensitivity of the initial imperfection on the magneto-plastic instability, expressed by an ampli?cation function, is obtained by solving the dynamic equation of de?ection of the plate after the inertial force in the transverse direction is taken into account. The results obtained show that the critical magnetic ?eld is sensitive to the plastic characteristic, e.g., hardening coe?cient, and the instability mode and de?ection of the plate are dependent on the geometrical imperfection as well.

STOCHASTIC BOUNDARY ELEMENT METHOD FOR RELIABILITY ANALYSIS OF PLATE AND BEAMS COMPOSITE STRUCTURES

In this paper, the reliability of orthotropic plate and beams composite structures, which is under the actions of the stochastic loading and stochastic boundary conditions, have been analyzed by stochastic boundary element method. First, the boundary integral equation of orthotropic plate and beams composite structures is given in this paper, and then based on the stochastic boundary element method, the method for reliability analysis of stochastic structures is establishes and formulas for computation of reliability index of orthotropic plate and beams composite structures are obtained. The computed examples show the efficient of the method used in this paper.

MECHANICAL VIBRATIONAL POWER FLOW IN BEAM-PLATE ASSEMBLIES

The vibrational power flow in the beam-plate assemblies and then with the isolators is investigated using analytical ' power flow' approach based on the some concepts of mechanical mo- bility and structural dynamics. Theoretical expressions of the power flow in the structures are given and examined. The numerical results of the expressions are good agreements with the measuring re- sults obtained by the technique of vibration intensity. On the basis of these results, possible ways of reducing the vibrational power flow in the structures are suggested .

NONLINEAR VIBRATION OF BEAMPLATES WITH A DELAMINATION

The problem of beam-plates with a delamination located at anarbitrary site undergoing non- linear free vibration without damp isinvestigated. For this problem, nonlinear governing equations as wellas the continuity, equilibrium and compatibility conditions areestablished. The Galerkin method and harmonic balance method areemployed to find solutions. Finally, in some examples,amplitude-frequency curves of the delaminated structure are presentedin order to reveal some special dynamic features.

Design of phase plates for shaping partially coherent beams by simulated annealing

Taking the Gaussian Schell-model beam as a typical example of partially coherent beams, this paper applies the simulated annealing （SA） algorithm to the design of phase plates for shaping partially coherent beams. A flow diagram is presented to illustrate the procedure of phase optimization by the SA algorithm. Numerical examples demonstrate the advantages of the SA algorithm in shaping partially coherent beams. An uniform flat-topped beam profile with maximum reconstruction error RE 〈 1.74% is achieved. A further extension of the approach is discussed.

Research on Vibration Suppression of the Finite Plate with Square Steel Beams Using Traveling Wave Method

The vibration suppression of the finite plate with square steel beams is studied using traveling wave method. The finite plate with square beams is modeled as the coupling systems between the plate flexural motion and the flexural and torsional motions for the square beams. The vibration response at any position of the coupling structure can be obtained by wave method. Numerical results show that comparing to finite element method (FEM), not only the low frequency but also the medium-high frequency vibration response of the finite plate with square beam can be effectively calculated by wave method. The suppression effect can be increased as the square beam is located at one-third of the length of plate or increasing the height of the beam. The study provides reference for arranged square beams applying to vibration suppression of ship and train structures.

BENDING THEORIES FOR BEAMS AND PLATES WITH SINGLE GENERALIZED DISPLACEMENT

Classical bending theories for beams and plates can not be used for short, stubby beams and thick plates since transverse shearing effect is excluded, and ordinary theories with multiple generalized displacements can not be used for long, slender beams and thin plates since the innate relation between rotation angle and deflection is ignored. These two types of theories are not consistent due to the contradiction of dependence and independence of the rotation angle. Based on several basic assumptions, a new type of theories which not only include the transverse shearing effect is presented, but also the relation between potation angle and deflection is obtained. Analytical solutions of several simple beams are given. It has been testified by numerical examples that the new theories can be used for either long, slender beams and thin plates or short, stubby beams and thick plates.

Finite element analysis on temperature field and residual stress of welding assembly for I-beam and end-plate

Based on full scale model of 1-beam and end-plate welding assembly with medium plate, welding temperature field and residual stress were simulated, infrared thermometers were employed to measure the real-time temperature Jbr verification purposes. Results show that the measured thermal cycle curves match well with the simulation result. Simulation results of welding residual stress indicate that the values of longitudinal and transverse stress on the upper surface of the plate are higher than the normal stress; higher tensile stresses exist at the end of the web weld toes and in the central area of the flange weld toes. The dangerous zones are located at the central areas of weld toes of the flange welds and near weld toes of the web welds.

Vacuum electron beam brazing technology and finite element analysis on temperature field of capillary to plate joint

Some parts with capillary to plate joint have important application in aerocrafi. Vacuum electron beam brazing （VEBB） technology is used to realize this jointing with capillaries. Firstly 3D finite element analysis model is built in this paper according to this special structure. And then ANSYS finite element analysis software is used to analyze brazing temperature field at different brazing parameters. The calculation results show that the temperature field of simulation has good agreement with that measured by experiment, which proves dependence of the model built in this paper. And also reference parameters could be provided for real brazing process through calculation in this model. Brazed joint of capiUary to plate with good performance is achieved using VEBB technology. The achievement of the study will be applied in aerocrafi in the future.

基于“板-梁理论”单轴对称FGM工字形梁组合扭转

针对目前功能梯度材料(Functionally Graded Materials,FGM)工字形截面梁为研究对象的研究较少,本研究以“板-梁理论”为基础,以上翼缘为矩形实体单轴对称的工字形截面梁为对象,展开组合扭转理论研究。基于“板-梁理论”,推导总应变能方程,得到梁的翘曲刚度和自由扭转刚度,然后通过外力势能公式和总应变能公式逐步推导得出总势能表达式。在此基础上,利用能量变分模型和微分方程模型,结合边界条件,推导出梁端部最大扭转角计算公式,将求出的最大扭转角与ANSYS建立的有限元模型结果进行对比。误差最小为0.01%,误差最大为1.85%。本文推导了FGM沿宽度变化上翼缘为矩形实体单轴对称工字形梁的组合扭转总应变能表达式,给出了一端固定、一端自由边界条件下扭转角及最大扭转角的表达式,从而进一步验证“板-梁理论”的正确性。

外嵌钢板UHPC无腹筋梁抗剪性能试验研究

超高性能混凝土(ultra-high performance concrete,UHPC)构件通常设计为无腹筋梁等薄壁形式,以适应结构装配化的需求。为提高UHPC无腹筋梁的抗剪承载力并简化施工,提出外嵌钢板UHPC无腹筋梁的新型结构形式。选取钢板面积、间距、倾斜角度、单侧或双侧布置为试验参数,完成7片UHPC梁的抗剪性能试验,获得各试验梁的裂缝分布、破坏模式、抗剪承载力及剪切延性等结果。基于桁架-拱理论,提出外嵌钢板UHPC无腹筋梁的抗剪计算模型,推导了相应的计算公式。结果表明:外嵌钢板能够有效提升UHPC无腹筋梁的抗剪强度,斜裂缝均能越过钢板,钢板能起到和箍筋类似的作用;将箍筋分项抗剪贡献换算为等量钢板的外嵌钢板梁承载力略低于有腹筋梁,在同等用钢量下,钢板单、双侧布置对承载力影响不大;斜向钢板试件裂缝发展更为充分,双面外嵌钢板梁表现出较好的剪切延性;按桁架-拱理论的计算值与试验值之比为1.02,吻合较好。外嵌斜钢板梁表现出良好的结构性能,具有较好的研究潜力和应用前景。

带悬臂板单箱双室薄壁箱梁畸变效应分析

为研究带悬臂板单箱双室薄壁箱梁的畸变效应,基于板梁框架法建立了畸变控制微分方程,给出竖向偏心集中荷载作用下该方程的初参数解,同时还导出了带悬臂板单箱双室截面箱梁畸变框架惯性矩的具体解析式.利用解析理论对悬臂梁和简支梁算例进行分析,研究结果表明:解析解与已有文献和有限元计算结果均吻合良好,验证了解析理论的正确性;通过参数分析可知,中腹板厚度越大,双室箱梁的抗畸变变形能力越强,中腹板厚度的变化对边腹板横向弯矩的影响很小,但中腹板的横向弯矩随其板厚的增大而增大,当中腹板厚度与边腹板厚度相等时,中腹板的横向弯矩可近似等于边腹板横向弯矩的2倍.

钢筒仓环板环梁稳定承载力的中外规范比较

钢筒仓在仓壁、仓裙及漏斗相交处容易发生平面外屈曲破坏,通常在相交处设置一道环梁来抵抗破坏,相交处环梁稳定对钢筒仓安全运行起着至关重要的作用。环梁通常分T型环梁与环板环梁2种。环板环梁宽度、环板环梁厚度是环板环梁的2个主要参数,为进一步研究其对环板环梁稳定承载力的影响,以某项目钢筒仓环板环梁为例,分别依据中国规范、欧洲规范的计算方法,深入研究环板环梁宽度、环板环梁厚度与环板环梁稳定承载力的关系,比较分析中国规范与欧洲规范计算值之间的差异,提出合理化建议,为类似工程提供参考。

全逆作法深基坑钢筋安装工程施工技术研究

超深基坑现场施工阶段存在较多的问题,其中钢筋吊运、后置构件安装等难度较大,容易影响安装施工效果。文章结合实际工程案例提出了全新的逆作钢筋工程施工技术。该技术融合吊物孔与塔吊、电动葫芦多元吊运系统,采取后置构件悬挂式钢筋安装法。然而在应用该技术时,梁柱接头部位容易产生严重损坏问题,导致结构性能无法达到工程的标准,因此需要采取合理的解决方案以及施工措施,克服施工难题。

3D打印导板引导正畸微种植钉植入的精确性

背景:微种植体体积较小,在进行植入手术时可能会伤及上颌窦、相邻牙根及下颌神经,这要求在微种植体植入手术时需要精确的定位、准确的植入方向。目的:探讨基于锥形束CT的3D打印导板引导正畸微种植钉植入的临床应用价值。方法:选择2021年12月至2023年12月贵州医科大学附属口腔医院收治的需植入微种植体增强支抗患者16例,收集患者眼眶下缘至舌骨水平的牙颌锥形束CT扫描数据,将数据导入Mimics 17.0进行阈值分割,获取牙冠、牙根及骨皮质三维模型,使用iTero口腔扫描仪扫描获得患者口内软硬组织的数字模型,将CT影像与口扫模型进行优化重叠,设计、制作3D打印微种植体导板,在微种植体导板引导下植入微种植体16枚。术后进行锥形束CT拍摄,通过术后锥形束CT三维重建,选取微种植体与牙体最接近的层面进行距离测量,评估微种植的安全性;对比手术前后锥形束CT影像,测量微种植钉冠部、尖部偏差及微种植钉冠部与尖部角度偏差。正畸随访6个月,记录微种植体松动及脱落情况。结果与结论:术后影像显示16颗支抗钉未与牙根或邻近组织接触,手术前后影像对比显示,支抗钉帽端距离偏差为(1.07±0.65)mm,支抗钉尖端距离偏差为(1.51±0.47)mm,微种植钉冠部与尖部角度偏差为(7.40±4.63)°,微种植体与牙体最接近的层面距离为(1.17±0.45)mm,安全性Ⅰ级10颗,安全性Ⅱ级3颗。随访结果显示16颗微种植钉未出现松动、脱落情况,稳定性良好。结果表明,基于锥形束CT的3D打印导板引导正畸微种植钉植入具有良好的精确性与稳定性。

AN ANALYSIS ON CHARACTERISTIC OF MAGNETOELASTICITY OF A MAGNETIC FIELD MICROSENSOR MADE OF CANTILEVERED PLATES WITH FERROMAGNETIC FILMS

The purpose of this paper is to study the magnetomechanicalcharacteristic of a microsensor which is composed of a cantileveredbeam-plate with ferromagnetic films in order to measure the magneticfield from the deformation of plate when the microsensor is locatedin the magnetic field. To this end, a nu- merical approach made up ofthe finite element method for magnetic field and the finitedifference method for deflection of the microsensor is proposed toperform the numerical analysis of deflection under magnetoelasticinteraction. Some quantitative results of a case study for themagnetoelastic characteristic between the mag- netic field anddeflection of the microsensor in the magnetic field are given. Theresults show that this mi- crosensor can be used not only to measurethe magnitude of magnetic intensity, but also to possibly monitor thedirection of the vector of the magnetic field.

Fracture Assessment for Electron Beam Welded Damage Tolerant Ti-6Al-4V Alloy by the FITNET Procedure

Fracture assessment of the cracked structures is essential to avoiding fracture failure.A number of fracture assessment procedures have been proposed for various steel structures.However,the studies about the application of available procedures for titanium alloy structures are scarcely reported.Fracture assessment for the electron beam(EB) welded thick-walled damage tolerant Ti-6Al-4V(TC4-DT) alloy is performed by the fitness-for-service(FFS) FITNET procedure.Uniaxial tensile tests and fracture assessment tests of the base metal and weld metal are carried out to obtain the input information of assessment.The standard options and advanced options of FITNET FFS procedure are used to the fracture assessment of the present material.Moreover,the predicted maximum loads of compact tensile specimen using FITNET FFS procedure are verified with the experimental data of fracture assessment tests.As a result,it is shown that the mechanical properties of weld metal are inhomogeneous along the weld depth.The mismatch ratio M is less than 10% at the weld top and middle,whereas more than 10% at the weld bottom.Failure assessment lines of standard options are close to that of advanced option,which means that the standard options are suitable for fracture assessment of the present welds.The accurate estimation of the maximum loads has been obtained by fracture assessment of standard options with error less than 6%.Furthermore,there are no potential advantages of applying higher options or mismatch options.Thus,the present welded joints can be treated as homogeneous material during the fracture assessment,and standard option 1 can be used to achieve accurate enough results.This research provides the engineering treatment methods for the fracture assessment of titanium alloy and its EB welds.