Advanced Materials Research Vols. 1065-1069

Abstract: In this paper, some numerical verifications would be presented and discussed, mainly including the following three types: (1) the pure bending beam in which the structural stiffness would maintain the original value and not change along with the load; (2) the clamped arc-beam in which the structural stiffness would decrease gradually with the increment of load and the structure would be buckling at some certain load value; and (3) the cantilever beam in which the structural stiffness would increase significantly with the increment of load. For all of the above examples, the present results are in good agreement with the analytical results and numerical results in other literatures, testifying and illustrating the validity of the large rotation matrix for nonlinear framed structure, which is developed in the part 1 of this paper.

Abstract: As an exploration and extension of load/unload response ratio theory, unload/ load response ratio theory (ULRR for short) is introduced firstly, and the relationship between ULRR (Y′) and elastic modulus (E for short) is obtained. Based on the basic theory of damage mechanics,the relationship between ULRR and damage variable (D for short) is set up and analyzed with the relationship between E and D. The unloading and loading experiments on a two-story structure carried out in the University of Naples in Italy are introduced;and calculated damage variable is compared with that calculated by Zhang Langping who put forward Weibull distribution as random distribution function. The results show that damage variable of the structure keep highly consistent with calculations of these two methods. Therefore, the relationship between Y′and D provides a new approach to a health assessment to catastrophic failure of large-scale structures and prediction of engineering.

Abstract: Based on the two-dimensional theory of elasticity, Hamiltonian system is introduced to solve the bending of orthotropic beams and the original problems come down to solve the eigensolutions of zero eigenvalue. The symplectic concept makes no hypothesis of deformation along the thickness direction. Thus, the current method can precisely analyze beams with arbitrary depth-to-length ratio, and can deal with arbitrary end conditions. In additional, a new improved boundary conditions for fixed ends beam is presented. Numerical examples showing comparison with other methods are given to illustrate the accuracy of the present approach.

Abstract: Hydraulic orienter has been widely used to alter the drilling direction downhole in coiled tubing drilling. A problem is encountered in construction field. When torque and drag of bottom hole assembly (BHA) are over the maximum output torque of orienter, This caused that it difficult to orient. Therefore, we need to calculate the maximum torque and drag in the process of orientation, it can provide a theoretical basis for designing and selecting the hydraulic orienter. Compared with the conventional force analysis, this paper additionally considered the case of zero weight on bit (WOB), the impact of the mud viscous forces and the relationship between dynamic and static friction, so that we can get more precise result of force analysis.

Abstract: Direct force method based on finite element for the calculation of the internal force of cross section has the advantages of high accuracy and stability. However, the method can only be applied to the sections with element boundary surface, which limits the application scope of the method. Given the advantages of direct force method based on finite element in calculating the internal force of cross section, a new approach for calculating internal force of cross sections in any location is proposed in this study. In this approach, the inverse isoparametric mapping and the direct force method based on finite element are combined together to solve the internal force of cross section at any location in a finite element model.

Abstract: This document proposed the test scheme of limit Test-bench structural system under the setting-out conditions of simulating critical state and completed the design and manufacture of the test system through conducting investigation on test methods and equipment of tension stringing construction process, combining the 1,250mm² large cross-section conductor and construction technology requirements and based on functional positioning, optimization of combined design and force analysis of Test-bench, mechanics analysis of various parts and their connection as well as allowable stress method check. This system was closer to the actual stringing working conditions, and the obtained data were more reasonable and exact and meet the actual engineering demand. In addition, the reliability of this test system has been verified through the test of 1,250mm² third-class large cross-section conductor.

Abstract: For a mouth shaped strucure with bolt connection, the mechanical response and thread stress distribution were studied by experimental and numerical method. The structure was tested with variety of the pretension loads from 10 N.m to 70 N.m . In this paper, a numerical method modeling the helical thread was proposed. In the method, the structure was divided into three regions, thread region, conventional region and transition region. The conventional region was modeled with the conventional method, however, the thread region and the transition region were modeled using the Glide-Guide method. Firstly, two helical lines and the plane elements were created. Secondly, the plane elements were rotated along the lines, then the three dimensional elements for the helical model were obtained. Finally, the nodes of the transition region elements and the conventional region elements were merged so that the whole model was attained. The experimental structure was modeled by the method, and the mechanical response and thread stress distribution were obtained. The results show that the axial stress of the screw obtained by experiment and the numerical method were very close, and they were both close to the empirical formula when the equivalent friction coefficient was 0.22 . Comparing to the existing methods, the numerical method proposed in the article is mush simpler, and it can obtain reasonable results using all standard elements.

Abstract: The instability and dynamics behavior of a cantilevered thin-elastic plate with large deformation subjected to axial flow is studied numerically. The structural dynamics equation is discretized by isoparametric displacement-based finite, and the motion of a continuous fluid domain is governed by two-dimensional incompressible viscous Navier-Stokes equations, which discretized by finite volume method. The two-dimensional numerical model of two-way fluid-structure coupling is established combined with moving mesh technology, realizing the interaction of thin-elastic plate and axial fluid. Firstly, under given different flow velocity, the stability of limit-cycle oscillations has been studied through Hopf bifurcation, time trace, vibration responses. Secondly, the fluid domain features are analyzed qualitatively by separately comparing with vorticity under given different flow velocity, and cloud diagram of pressure and velocity are also analyzed at U=3.6m/s.

Abstract: The differential equation of fluid-conveying pipes considering distributed follower force and elastic foundation is established. The equation is discreted and solved by Galerkin method and the frequency characteristic values are solved by bending moment transfer method. The effects of crack location and elastic foundation stiffness to the form of instability of the pipes under the distributed follower force are analyzed. Results show that the elastic foundation stiffness can enforce the stability of the pipes effectively, and the effects are more obvious when the crack location is closer to the middle of the pipe.

Abstract: The iterative formulas of spring forces for Circumferential Arc Spring Dual Mass Flywheel (DMF-CS) were derived by discrete method, involving friction forces. The computation program was designed, and the curves illustrating transmitted torques over deformation angles of the outer and inner arc springs were plotted, which showed linear torque behavior. Thus two stages of torsional stiffness of DMF-CS were figured out to be 465.9923Nm/rad and 631.7980Nm/rad. The two stages of torsional stiffness without friction forces were calculated by this method, which were 434.6408Nm/rad and 591.3652Nm/rad. The experiment of static torque characteristic of DMF-CS was completed, obtaining the experimental torsional stiffness, which were 455.9923Nm/rad and 620.9412Nm/rad. Comparing the above values of torsional stiffness, the values with friction forces show more precise than ones without friction forces, and the values without friction forces are smallest. The results show that the friction forces contribute to the torsional stiffness of DMF-CS.