A high-frequency model of a circular beam with a T-shaped cross section

2019 ◽  
Vol 145 (3) ◽  
pp. 1792-1792
Author(s):  
Andrew J. Hull ◽  
Daniel Perez
Keyword(s):  
Cross Section ◽  
High Frequency ◽  
Frequency Model ◽  
Circular Beam ◽  
Shaped Cross Section

scholarly journals A High-Frequency Model of a Circular Beam with a T-Shaped Cross Section

Acoustics ◽  
2019 ◽  
Vol 1 (1) ◽  
pp. 295-336
Author(s):  
Andrew Hull ◽  
Daniel Perez
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
Cross Section ◽  
High Frequency ◽  
Algebraic Equations ◽  
Frequency Range ◽  
Linear Algebraic Equations ◽  
Circular Beam ◽  
The Web ◽  
Shaped Cross Section

This paper derives an analytical model of a circular beam with a T-shaped cross section for use in the high-frequency range, defined here as approximately 1 to 50 kHz. The T-shaped cross section is composed of an outer web and an inner flange. The web in-plane motion is modeled with two-dimensional elasticity equations of motion, and the left portion and right portion of the flange are modeled separately with Timoshenko shell equations. The differential equations are solved with unknown wave propagation coefficients multiplied by Bessel and exponential spatial domain functions. These are inserted into constraint and equilibrium equations at the intersection of the web and flange and into boundary conditions at the edges of the system. Two separate cases are formulated: structural axisymmetric motion and structural non-axisymmetric motion and these results are added together for the total solution. The axisymmetric case produces 14 linear algebraic equations and the non-axisymmetric case produces 24 linear algebraic equations. These are solved to yield the wave propagation coefficients, and this gives a corresponding solution to the displacement field in the radial and tangential directions. The dynamics of the longitudinal direction are discussed but are not solved in this paper. An example problem is formulated and compared to solutions from fully elastic finite element modeling. It is shown that the accurate frequency range of this new model compares very favorably to finite element analysis up to 47 kHz. This new analytical model is about four magnitudes faster in computation time than the corresponding finite element models.

scholarly journals A High-Frequency Model of a Rectilinear Beam with a T-Shaped Cross Section

Acoustics ◽  
2019 ◽  
Vol 1 (3) ◽  
pp. 726-748
Author(s):  
Andrew J. Hull ◽  
Daniel Perez ◽  
Donald L. Cox
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
Analytical Model ◽  
Cross Section ◽  
Timoshenko Beam ◽  
High Frequency ◽  
Plane Motion ◽  
Beam Model ◽  
Frequency Range ◽  
Shaped Cross Section

This paper derives an analytical model of a straight beam with a T-shaped cross section for use in the high-frequency range, defined here as approximately 1 to 35 kHz. The web, the right part of the flange, and the left part of the flange of the T-beam are modeled independently with two-dimensional elasticity equations for the in-plane motion and Mindlin flexural plate equation for the out-of-plane motion. The differential equations are solved with unknown wave propagation coefficients multiplied by circular spatial domain functions. These algebraic equations are then solved to yield the wave propagation coefficients and thus produce a solution to the displacement field in all three directions. An example problem is formulated and compared with solutions from fully elastic finite element modeling, a previously derived analytical model, and Timoshenko beam theory. It is shown that the accurate frequency range of this new model is significantly higher than that of the analytical model and the Timoshenko beam model, and, in the frequency range up to 35 kHz, the results compare very favorably to those from finite element analysis.

scholarly journals Influence of technical parameters on the structure of annular axis braided preforms

2021 ◽  
Vol 28 (1) ◽  
pp. 160-168
Author(s):  
Xi Wang ◽  
Guoli Zhang ◽  
Xiaoping Shi ◽  
Ce Zhang
Keyword(s):  
Cross Section ◽  
Rotation Speed ◽  
Technical Parameters ◽  
Braiding Angle ◽  
Shaped Cross Section

Abstract A modified vertical braiding machine and closed annular axis mandrels with a special-shaped cross section were used to braid annular axis preforms under four different technical parameters. After measuring the braiding angles and yarn spacing of the braided preform in different areas of the mandrels, it was found that the braiding angle increased by 20.9% and the yarn spacing decreased by 19.8% when the speed of the yarn carrier was doubled. The braiding angle decreased by 31.1% and the yarn spacing increased by 28.6% when the rotation speed of the mandrels was doubled. The results show that the rotation speed of the mandrel has a slightly greater influence on the braiding angle and the yarn spacing. By using the modified braiding machine to braid the annular axis preforms, multi-layer continuous braided preforms can be achieved on compact equipment. And the structure of the annular axis braided preforms can be changed by changing the technical parameters.

scholarly journals Design of an Edge Slotted Waveguide Antenna Array Based on T-Shaped Cross-Section Waveguide

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Teng Li ◽  
Wenbin Dou
Keyword(s):  
Surface Wave ◽  
Antenna Array ◽  
Cross Section ◽  
Mutual Coupling ◽  
Dominant Mode ◽  
Waveguide Structure ◽  
Center Frequency ◽  
Sidelobe Level ◽  
Slotted Waveguide ◽  
Shaped Cross Section

An edge slotted waveguide antenna array based on T-shaped cross-section radiating waveguide is proposed. The T-shaped waveguide is analyzed and designed to operate in dominant mode around the center frequency, which has a lower profile compared with the rectangular one. The radiating slots are etched and rotated alternatively on the broadened top plate without cutting into the adjacent walls. The metal fences are inserted between slots to reduce the mutual coupling and surface wave. Therefore, the sidelobe level in E-plane is well suppressed. A 2 × 8 antenna array working at Ka-band is designed and fabricated. The measured results agree well with simulations which demonstrate this novel waveguide structure.

The scaled RCS measurement method for lossy targets via dynamically matching the reflection coefficients in the THz band

2021 ◽  
Author(s):  
Shuang Pang ◽  
Yang Zeng ◽  
Qi Yang ◽  
Bin Deng ◽  
Hong-Qiang Wang
Keyword(s):  
Cross Section ◽  
High Frequency ◽  
Measurement Method ◽  
Dielectric Material ◽  
Frequency Estimation ◽  
Estimation Method ◽  
Physical Optics ◽  
Reflection Coefficients ◽  
Effective Solution ◽  
Terahertz Band

Abstract In the terahertz band, the dispersive characteristic of dielectric material is one of the major problems in the scaled radar cross section (RCS) measurement, which is inconsistent with the electrodynamics similitude deducted according to the Maxwell’s equations. Based on the high-frequency estimation method of physical optics (PO), a scaled RCS measurement method for lossy objects is proposed through dynamically matching the reflection coefficients according to the distribution of the object’s facets. Simulations on the model of SLICY were conducted, the inversed RCS of the lossy prototype was obtained using the proposed method. Via comparing the inversed RCS with the calculated results, the validity of the proposed method is demonstrated. The proposed method provides an effective solution to the scaled RCS measurement for lossy objects in the THz band.

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