Rod Members Research Articles

A non-uniform lattice design method for lightweight structures in 3D printing

Lightweight design is an essential topic in aerospace, automotive and other fields. In automobile manufacturing, the engine connecting rod is one of the main components; its lightweight design has a high reference value. And 3D printing provides a feasible solution for designing and manufacturing lightweight structures. Unlike the traditional geometrically homogeneous point design, this study offers a non-homogeneous point design method based on the spatial stress state of additively manufactured components. After numerical simulation of quasi-static stresses on a model of an engine connecting rod, finite element grid cells with different stress values are replaced by lattice cells with different specific stiffnesses at similar local stress levels. The overall specific stiffness of the structure is further improved by continuing the optimized design with the corresponding gradient-type reinforcement of the non-uniform lattice structure. The basic idea of this design is to perform non-uniform adaptive filling of solid parts under localized loading by employing different types of unit cells. Stereolithography 3D printing technology prepares the engine lattice structural parts for quasi-static compression comparison experiments and fracture analysis after failure. The conclusions show that the engine connecting rod members with non-homogeneous lattice have more excellent overall mechanical properties than homogeneous lattice members. This work demonstrates the feasibility of such design methods for 3D printing lightweight structures and optimization.

Research on Calculation of Bearing Force of Composite Insulation Cross Arm Pressure Rod of 220kV Power Transmission Line Pole Tower

The lower pressure rod of composite insulation cross arm of power transmission line pole tower is connected with the pole tower body and the coupling end joint respectively. The connection pattern on both ends of lower pressure rod are connected with slot type flash board, cross type flash board, U-shaped flash board, etc. The most frequently adopted one is connecting the cross type flash board on one end with the tower body, and connecting the slot type flash board on the other end with the joint of coupling end. The lower pressure rod of this pattern is that one end is axis connection while the other end is eccentric connection, and the calculation method for axial pressure bearing force is not suitable any longer. This paper conducts pressure test and finite element analysis on the solid composite material circular core rod member which is connected with cross type flash board on one end and slot type flash board on the other end, proposes the slenderness ratio correction coefficient of lower pressure rod of composite insulation cross arm of 220kV power transmission line pole tower, and provides basis for standardization of calculation method for bearing force of composite insulation cross arm pressure rod of power transmission iron tower.

Thermal-structural dynamic analysis of a satellite antenna with the cable-network and hoop-truss supports

Thermally induced structural disturbances of the flexible appendages on a satellite usually occur during eclipse transitions. As a large-scale space structure consists of rod members, cyclic thermal shock induced vibrations such as the divergent thermal flutter may be crucial for its functional serving. In this article, the motivation is to estimate the dynamical behaviors of the AstroMesh antenna under solar flux shock. For this purpose, we developed a numerical approach for the thermal-structural coupling analysis of tensegrity structures considering the pre-stressed state after the form-finding process. The Euler-Bernoulli beam theory, the pre-stressed bar model, and the Fourier thermal element are employed in conjunction with the special consideration on the effect of structural deformations on absorbing solar flux. It is found that, unlike the single boom structure, thermal deformations of the AstroMesh antenna are mainly caused by the temperature variation along rod axis-direction, rather than the temperature gradient on rod cross-section. Besides, the phenomenon of thermally induced vibrations can hardly happen in the AstroMesh antenna.

Effects of Support Conditions to the Post-Buckling Behaviors of Axially Functionally Graded Material Rods

The effects of support conditions to the post-buckling behaviors of rod structures made of Axially Functionally Graded Material (AFGM) are presented. The material property of the rod member is assumed to vary linearly in the axis direction of the member. The non-linear material property of the rod element is formulated in the Finite Element context. The consistent shape functions for the rod element were developed to take into account the varying material property in the finite element formulation. The geometrically non-linear behavior of the rod element is formulated in the context of the updated co-rotational formulation. The non-linear equilibrium equations are solved by using the incremental and iterative procedures in combination with the arc-length control method. The influences of the material distribution on the post-buckling behaviors of the AFGM Williams’ toggle frames under various support conditions are highlighted. As a result, the graded between two materials can increase the post-buckling behaviors of the AFGM rod element regardless of the types of support conditions. The orientation of material distributions combined with the type of support condition can increase the performance of the rod element. The fixed-fixed support condition showed the highest performance of the AFGM rod element.

Finite Element Analysis for the Collapse Accident of One 110kV Transmission Tower

One collapse tower of 110 kV transmission line was taken as an example and a finite element model for the coupled tower-line system was established for investigating the effects of the strong wind on the transmission tower and line. The result shows that the selected standard of material of some rod members is lower, and the area of their section is relatively small. Main legs present buckling instability because of being in compression under action of the strong wind, which leads to the collapse accident of the towers.

Evaluation of vibration control system with U-dampers based on quasi-linear motion mechanism

This paper presents a new vibration control system for protection of steel structures from earthquakes. The proposed system, which uses a quasi-linear motion mechanism, achieves dissipation of seismic energy into the structure through yielding of U-shaped steel dampers. Based on the linear motion mechanism characteristics, the bracing members are subjected only to tensile force. This feature can eliminate the brace-buckling problem for braces, making rod members applicable to bracing members. This paper presents an outline of the vibration control system with subsequent evaluation of the lateral stiffness and strength of the frames with the proposed device. Six cyclic loading tests are conducted using the frame models with the proposed system. The accuracy of the evaluation is discussed by comparing the cyclic loading test results.

The Effect of Mutual Orientation on the Spectra of Metal Nanoparticle Rod−Rod and Rod−Sphere Pairs

A simple quasistatic treatment for the plasmon resonance spectra of nanoparticle rod−rod and rod−sphere pairs is presented. Spectra are calculated for gold particle pairs at different distances and mutual orientations. For rod−rod and rod−sphere pairs, the spectral changes that occur as a result of interparticle interaction are different for end-to-end (axial) and side-to-side (lateral) orientations. Axial interactions generally lead to a red shift of the most intense (longitudinal axis) plasmon resonance band. Lateral interactions usually lead to a blue shift of the main plasmon band. In general, lateral orientation yields more pronounced spectral changes than the axial case, especially as the aspect ratio of the rod member(s) increases.

Oscillating rod member equipped with dynamic damper

A rod-damper combination comprising an oscillating rod member and a dynamic damper mounted on the rod member is disclosed. The dynamic damper includes a mass portion having a substantially cylindrical shape, and two elastic support members formed on axially opposite sides of the mass portion to elastically support the mass portion. The oscillating rod member includes a small-diameter portion formed at an axially middle portion thereof, and two large-diameter portions formed on axially opposite sides of the small-diameter portion. Alternatively, the rod member includes a middle portion, and two tapered portions on axially opposite sides of the middle portion. The two elastic support members of the dynamic damper are mounted on the two large-diameter or tapered portions of the oscillating rod member, respectively.

Optimal design of flexible rod structural members

The problems of optimal design of flexible rod members connected to a carrying body undergoing programmed motion with respect to the center of mass of the system, are examined. The problems are solved by solving directly optimal-control problems with phase constraints in the form of inequalities. The results of optimization of the shape of a flexible member, the distribution of mass and stiffness along a flexible member with an azimuthat contour of the axis, and determination of the optimal distribution of mass and stiffness along the member with the optimal contour of the axis are presented. It is concluded that inertially loaded flexible rods are extremely sensitive to the geometry and the distribution of material.

Structural design and decoupled control

The decoupled control of an optimally designed space structure is considered. The optimal structure is a derivative of the CSDL I model spacecraft. In particular, the effects of structural perturbations on the optimal design are considered. The stiffness matrix for the structure is perturbed by changing the areas of its rod members. A LQR controller, with modal suppression is designed for the nominal system. The controller is used on the perturbed systems and the effects on modal suppression noted. The spillover into the suppressed modes due to perturbations is also quantified in terms of the change in the row and column space of the control and observation matrices, respectively. The results obtained are compared to those obtained for the nominal CSDL I model.

Continuum modeling of three-dimensional truss-like space structures

A mathematical and computational analysis capability has been developed for calculating the effective mechanical properties of three-dimensional periodic truss-like structures. Two models are studied in detail. The first, called the octetruss model, is a three-dimensional extension of a two-dimensional model, and the second is a cubic model. Symmetry considerations are employed as a first step to show that the specific octetruss model has four independent constants and that the cubic model has two. The actual values of these constants are determined by averaging the contributions of each rod element to the overall structure stiffness. The individual rod member contribution to the overall stiffness is obtained by a three-dimensional coordinate transformation. The analysis shows that the effective three-dimensional elastic properties of both models are relatively close to each other.

Massive empyema due to Citrobacter diversus.

Citrobacter diversus is a gram-negative rod member of the Enterobacteriacease family. A patient is described from whom this organism was isolated twice in pure culture from empyema fluid. Our isolates of Citrobacter diversus were resistant to ampicillin and carbenicillin and sensitive to cephalothin. Citrobacter diversus should be distinguished from Citrobacter freundii, Enterobacter cloacae and Klebsiella pneumoniae. This organism joins Streptococcus pyogenes, bacteroids species, anaerobic streptococci and Escherichia coli as a cause of slight pneumonia with extensive empyema.

Massive Empyema Due to Citrobacter Diversus

Citrobacter diversus is a gram-negative rod member of the Enterobacteriaceae family. A patient is described from whom this organism was isolated twice in pore culture from empyema fluid. Our isolates of Citrobacter diversus were resistant to ampicillin and carbenicillin and sensitive to cephalotbin. Citrobacter diversus should be distinguished from Citrobacter freundii, Enterobacter cloacae and Klebsiella pneumoniae. This organism joins Streptococcus pyogenes, bacteroides species, anaerobic streptococci and Escherichia coli as a cause of slight pneumonia with extensive empyema.