Shear deformation effect in plates stiffened by parallel beams

In this paper a general solution for the analysis of shear deformable stiffened plates subjected to arbitrary loading is presented. According to the proposed model, the arbitrarily placed parallel stiffening beams of arbitrary doubly symmetric cross section are isolated from the plate by sections in the lower outer surface of the plate, taking into account the arising tractions in all directions at the fictitious interfaces. These tractions are integrated with respect to each half of the interface width resulting two interface lines, along which the loading of the beams as well as the additional loading of the plate is defined. Their unknown distribution is established by applying continuity conditions in all directions at the interfaces. The utilization of two interface lines for each beam enables the nonuniform distribution of the interface transverse shear forces and the nonuniform torsional response of the beams to be taken into account. The analysis of both the plate and the beams is accomplished on their deformed shape taking into account second-order effects. The analysis of the plate is based on Reissner’s theory, which may be considered as the standard thick plate theory with which all others are compared, while the analysis of the beams is performed employing the linearized second order theory taking into account shear deformation effect. Six boundary value problems are formulated and solved using the analog equation method (AEM), a BEM based method. The solution of the aforementioned plate and beam problems, which are nonlinearly coupled, is achieved using iterative numerical methods. The adopted model permits the evaluation of the shear forces at the interfaces in both directions, the knowledge of which is very important in the design of prefabricated ribbed plates. The effectiveness, the range of applications of the proposed method and the influence of shear deformation effect are illustrated by working out numerical examples with great practical interest.     

Classification of Teleparallel Homothetic Vector Fields in Cylindrically Symmetric Static Space-Times in Teleparallel Theory ofGravitation

In this paper we classify cylindrically symmetric static space-timesaccording to their teleparallel homothetic vector fields using directintegration technique. It turns out that the dimensions of the teleparallelhomothetic vector fields are 4, 5, 7 or 11, which are the same in numbers asin general relativity. In case of 4, 5 or 7 proper teleparallel homotheticvector fields exist for the special choice to the space-times. In the caseof 11 teleparallel homothetic vector fields the space-time becomes Minkowskiwith all the zero torsion components. Teleparallel homothetic vector fieldsin this case are exactly the same as in general relativity. It is importantto note that this classification also covers the plane symmetric static space-times.     

Finding Dirac Spin Effect in NUT Spacetime

In the present study, we are interested in finding the spin precession of a Dirac particle in expanding and rotating NUT spaeetime. A tetrad with two functions to be determined is applied to the field equation of the teleparallel theory of gravity via a coordinate transformation. The vector, the axial-vector and the tensor parts of the torsion tensor are obtained. We found that the vector parts are in the radial and Ф-directions. The axial-vector torsion is along r-direction while its other components along θ and oh-directions vanish everywhere. The vector connected with Dirac spin has been evaluated as well.     

Torsion Axial-Vector in an Alternative Kerr Tetrad Field

In the framework of parallelism general relativity, the torsion axial-vector in the rotating gravitational field is studied in terms of the alternative Kerr tetrad. In the case of the weak field and slow rotation approximation, we obtain that the torsion axial-vector possesses the dipole-like structure. Furthermore, the effect of massive neutrino spin precession in this field is mentioned.     

The coupling method for torsion problem of the square cross-section bar with cracks

By coupling natural boundary element method (NBEM) with FEM based on domain decomposition, the torsion problem of the square cross-sections bar with cracks have been studied, the stresses of the nodes of the cross-sections and the stress intensity factors have been calculated, and some distribution pictures of the stresses have been drawn. During computing, the effect of the relaxed factors to the convergence speed of the iterative method has been discussed. The results of the computation have confirmed the advantages of the NBEM and its coupling with the FEM. Foundation item: the State Key Laboratory of Science and Engineering Computation Biography: ZHAO Hui-ming (1971-)     

Inelastic coupled response of eccentric buildings with respect to different earthquake intensity

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｂｅｈａｖｉｏｒｏｆｌａｔｅｒａｌ＿ｔｏｒｓｉｏｎａｌｃｏｕｐｌｅｄｂｕｉｌｄｉｎｇｉｎｔｈｅｉｎｅｌａｓｔｉｃｒａｎｇｅｈａｄｂｅｅｎｗｉｄｅｌｙｉｎｖｅｓｔｉｇａｔｅｄ.ＫａｎａｎｄＣｈｏｐｒａ(1981)[1]ｓｔｕｄｉｅｄａｏｎｅ＿ｓｔｏｒｙｍｏｄｅｌｗｉｔｈｓｉｎｇｌｅｌａｔｅｒａｌｒｅｓｉｓｔａｎｔｅｌｅｍｅｎｔａｎｄｒｅａｃｈｅｄｔｈｅｃｏｎｃｌｕｓｉｏｎｔｈａｔｇｅｎｅｒａｌｌｙｔｈｅｒｅｓｐｏｎｓｅｉｎｔｈｅｉｎｅｌａｓｔｉｃｒａｎｇｅｉｓａｆｆｅｃｔｅｄｂ…     

预应变对中碳钢扭转疲劳特性的影响

应用扭转疲劳试验机对退火后的非预应变45#钢及其3种预应变材料进行 实验. 实验结果表明：预应变量小于5%时,与非预应变材料相比疲劳极限降低10\%; 预应变量大于5{%}时,随着预应变量的增加,其疲劳极限有恢复的趋势,当预应变量达到 8%时,预应变材料与非预应变材料的疲劳极限几乎相等;当循环应力达到1*10^7$时,各种试件表面都有明显的停留裂纹存在.     

Stability and initial postbuckling behavior of anisotropic cylindrical shells subject to torsion

The paper presents an analytical solution describing the stability and postbuckling behavior of a cylindrical shell made of an anisotropic material with one plane of symmetry and subjected to torques at the ends. The solution is found using Koiter's buckling theory and the Donnell-Mushtari-Vlasov theory of anisotropic shells. The force and deflection functions are approximated by trigonometric series that satisfy hinged boundary conditions. The system of algebraic equations to which the problem is reduced at the main stage of solution is analyzed. Specific results on stability and sensitivity to imperfections of boron-plastic shells consisting of layers with different reinforcement directions are obtained __________ Translated from Prikladnaya Mekhanika, Vol. 44, No. 1, pp. 48–73, January 2008.     

Tension–torsion fracture experiments—Part I: Experiments and a procedure to evaluate the equivalent plastic strain

Ductile failure experiments on a double notched tube (DNT) specimen subjected to a combination of tensile load and torque that was applied at a fixed ratio is presented. The experimental results extend those in Barsoum and Faleskog (2007a) down to zero stress triaxiality. A new and robust evaluation procedure for such tests is proposed, and a simple relation for the equivalent plastic strain at failure for combined normal and shear deformation, respectively, is developed. Tests were carried out on the medium strength medium hardening steel Weldox 420, and the high strength low hardening steel Weldox 960. The experimental results unanimously show that ductile failure not only depends on stress triaxiality, but is also strongly affected by the type of deviatoric stress state that prevails, which can be quantified by a stress invariant that discriminates between axisymmetric stressing and shear dominated stressing, e.g., the Lode parameter. Additional experiments on round notch bar (RNB) specimens are recapitulated in order to give a comprehensive account on how ductile failure depends on stress triaxiality, ranging from zero to more than 1.6, and the type of stress state for the two materials tested. This provides an extensive experimental data base that will be used to explore an extension of the Gurson model that incorporates damage development in shear presented in Xue et al. (2013) (Part II).     

三维欧氏空间中的几类特殊球面曲线

利用曲线的球面活动标架,通过解微分方程,给出了三维欧氏空间中几类特殊球面曲线的特征和分类.