Holistic Structural Analysis for V-SAT Earth Station Antenna Structures (O_set Type) by using Cohen's wind load Coe_cients

Abstract

With the advent of latest numerical tools for the detailed analysis of structures, it's now possible to carry out exhaustive sensitivity analysis of structures to choose the optimum design option for the given application. With the totalitarianism in the hardware and software domains, there is volcanic proliferation of F.E.A tools for handling of Holistic analysis of Spacecraft ground segment structures meant for Receiving (RX) and Transmitting (TX) Radio Frequencies (RF) signals. Contemporary structures viz Very Small Aperture Terminal (VSAT), Ultra Small Aperture Terminal (USAT), are using high RF for getting signals work on C, Ku and Ka bands. An attempt has been made in this work to carry out the Holistic F.E.A of 1.5 m (ϕ) VSAT Antenna Structure for wide gamut of new materials as an option for Mount, Backup, Reflector and Feed support structure in the hitherto fore unexplored domain of Earth Station Structures. Parallelly, a parabolic Direct to Home (DTH) reflector model was tested and verify with the analytical results in displacement domain. In this work various novel materials were used viz, Steel (SS303), Aluminum (6061-T6), Glass Fiber Reinforced Polymer (GFRP), Carbon Fiber Reinforced Polymer (CFRP) for comparison of F.E.A results with respect to Root Mean Square (R.M.S) and Pointing Error (P.E). For Super Structure. wind Load pre-processor has been generated in MATLAB and STAAD Pro EDITOR (MACROS) for various wind coefficient like Drag Force (CD), Lift Force (CL) and Moment (CM) for critical orientations in Operational, Gusting and Survival winds speeds using Edward Cohen's Empirical curves. Conclusions has been derived with respect to the best choice of materials for Antenna which meet the P.E and R.M.S Spec and reducing the weight of VSAT Antenna. The Wind load on the antenna structure is calculated based on the paper entitled “CALCULATION OF WIND FORCES AND PRESSURES ON ANTENNAS” by Edward Cohen and Joseph Vellozzi presented at ANNALS OF THE NEW YORK ACADEMY OF SCIENCES on June 26, 1964. The paper is the work based on several wind tunnel tests made on different diameter antennas and results are presented for pressure distribution as a % of chord length for various angles of attack. The pressure distribution on the reflector for the various angles of attack is taken from Fig.25 of the paper. In this piece of work, wind force calculations are performed for various elevation angles ranging from 0 to 90 degrees for a 1.5-meter diameter (ϕ) antenna under operational wind speed conditions of 80 kmph. Azimuth is maintained at a constant 0 degrees. To determine the antenna structure's critical position, the R.M.S values are obtained and compared. Parallely experiment has been also performed on DTH (Direct to Home Television) by simulating the Static wind load condition of 40 kmph wind speed. This work also focuses on the soil interaction in a holistic model by incorporating actual soil properties obtained from standard literature review. The holistic model is compared with a fixed base model and also with the modulus of subgrade reaction. By considering the soil interaction, this study provides valuable insights into the behavior and performance of the system under different conditions, allowing for improved analysis and design considerations. It’s also included the truck chassis analysis with supporting antenna and chassis has been analysis by considering the 3g loads on it as per JSS-55555 ministry of defense code.