A Semianalytic Method for Vibration Analysis of a Sandwich FGP Doubly Curved Shell with Arbitrary Boundary Conditions

Due to the excellent mechanical properties of doubly curved structure and functionally graded porous (FGP) material, the study of their vibration characteristics has attracted wide attention. The main aim of this research is to establish a formulation for free and forced vibration analysis of a new Sandwich FGP doubly curved structure. Four models of Sandwich materials are considered. The potential energy and kinetic energy functions are obtained on the foundation of the first-order shear deformation theory (FSDT). The idea of domain energy decomposition is applied to the theoretical modeling, where the structure is segmented along the generatrix direction. The continuity conditions for the interfaces between adjacent segments are balanced by the weighted parameters. For each segment, the displacement functions are selected as the Jacobi orthogonal polynomials and trigonometric series. The boundary conditions of the structure are obtained by the boundary spring simulation technique. The solution is obtained by the variational operation of the structural functional. The convergence performance and correctness of the theoretical model are examined by several numerical examples. Finally, some novel results are given, where free and forced vibration characteristics of Sandwich FGP doubly curved structures are examined in detail.

Evaluation of Behaviour of Plan Curved Structure Supported by Arch

New type of plan curved structure has been developed within the research of arch footbridges at Faculty of Civil Engineering of Brno University of Technology. Structural arrangement came out of study of behaviour of plan curved upper deck arch structures of various radii of curvature. The design method of such structures with ideal shape of arch was the outcome of the research. Results of numerical analysis were verified on physical model in scale 1:10, which has been built and tested. The model has been mounted with gauges – 41 strain gauges at various positions on concrete and steel part of the structure and 5 deflection sensors. Then the structure has been subjected to loads in various positions corresponding with load positions of variable loads in calculation model. The paper describes evaluation of measurement of stresses and deformations of physical model of plan curved structure supported by an arch. Obtained values of stresses and deformations were compared with values derived from FE calculation model.

A low profile compact three-way Wilkinson power divider with size reduction

In this study, a three-way Wilkinson power divider (WPD) was proposed the circuit whose center frequency was selected as 1.9 GHz operates between 0.95-2.95 GHz frequencies and has a bandwidth of approximately 105%. The simulation and measurement results of the designed circuit were well aligned with each other below 10 dB return loss and 13 dB isolation. In addition, 0.4, 0.3 and 1.0 dB insertion loss were obtained in the output ways, respectively. The circuit is made more compact thanks to the curved structure of the output ways. It has been found that the proposed three-way power divider takes about 35% less space than the conventional circuit design.

Offset effect on the S-Bend structure losses and optimization of its size for integrated optics

The S-Bend structures are heavily exploited to join optical components. Reducing the power loss caused by the curve is the main objective in the design step of these components. However integrated optical circuits require S-Bend waveguide to be low loss and compact sized. In this paper, we present a contribution to link the curved structure to the straight waveguide by using the simulated bend function available in the Beam propagation tool of the Rsoft commercial software package. Simulation results confirm that this approach allows a reduction of the size of the curved structure with offset with relatively minimum of losses for photonic field.

A Novel Biodegradable Multilayered Bioengineered Vascular Construct with a Curved Structure and Multi-Branches

Constructing tissue engineered vascular grafts (TEVG) is of great significance for cardiovascular research. However, most of the fabrication techniques are unable to construct TEVG with a bifurcated and curved structure. This paper presents multilayered biodegradable TEVGs with a curved structure and multi-branches. The technique combined 3D printed molds and casting hydrogel and sacrificial material to create vessel-mimicking constructs with customizable structural parameters. Compared with other fabrication methods, the proposed technique can create more native-like 3D geometries. The diameter and wall thickness of the fabricated constructs can be independently controlled, providing a feasible approach for TEVG construction. Enzymatically-crosslinked gelatin was used as the material of the constructs. The mechanical properties and thermostability of the constructs were evaluated. Fluid-structure interaction simulations were conducted to examine the displacement of the construct’s wall when blood flows through it. Human umbilical vein endothelial cells (HUVECs) were seeded on the inner channel of the constructs and cultured for 72 h. The cell morphology was assessed. The results showed that the proposed technique had good application potentials, and will hopefully provide a novel technological approach for constructing integrated vasculature for tissue engineering.

The Use of D Index in the Estimation of Aromaticity: The Case of Cycloparaphenylene

Cycloparaphenylenes are important compounds for their photophysical and electronic properties. The curved structure of these compounds induces an alteration of the aromatic character of these compounds. D values have been used to describe the aromatic character of compounds from [5]- to [10]cycloparaphenylene. D values are compared with HOMED and with the strain energy are obtained by using an homodesmotic reaction.