This paper focuses on SRMSAT STRUCTURE BUS which is a standardized Nano-Satellite structure bus. It provides a standard platform for a wide variety of missions in LEO and can be realized in a very short developmental period. The bus was designed and developed for SRMSAT, the SRM University (Sri Ramaswamy Memorial University) student Nano-Satellite, by the undergraduate students and faculty of SRM University in collaboration with Indian Space Research Organization (ISRO). The bus can support payloads up to a mass of 20kg. SRMSAT STRUCTURE BUS has a mass of around 6 kg and dimensions 280mm X 280mm X 280mm with an available volume of 11000 cc. Vibration Testing of the bus has been performed upto 6.7 gRMS. This makes the satellite capable of being launched by any launch vehicle in the world. An innovative PCB mounting design has been introduced in this structure bus which facilitates mounting of a maximum 7 PCB trays independently, each tray capable of holding a 250 mm 2 PCB. Structural analysis of SRMSAT STRUCTURE BUS was done using NX Nastran. The boundary conditions for each analysis were defined based on the loading conditions as specified by the launcher,
PSLV (Polar Satellite Launch Vehicle). Optimization of each individual component was performed by maintaining a minimum threshold between the local frequencies of the component and global frequencies of the entire satellite. Static, Modal, Harmonic and RandomVibration analysis of the structure bus was performed. This paper also describes the methodology followed in the static and dynamic analysis of the structure bus to finalize the design. The results have been tested and validated at ISRO Satellite Centre, Bangalore with around 90% accuracy and the structure has been certified as a standard structure bus for Nano-satellite missions. In terms of expandability, this structure bus is capable of accommodating deployable solar panels. Also, the payload mounting is not only restricted to the bottom deck but can also be done in the top or side decks as required for specific missions. This enhances the scope of small satellites which has not been possible with previous satellites of the same size. SRMSAT which utilized this bus was launched on-board PSLV C-18 on 12th October 2011 with the scientific objective of measuring greenhouse gases, namely CO 2 and H 2 O.
Nowadays it’s difficult to use a metal with high corrosion resistant properties in required applications. Monel 400 is one nickel based alloy having required property to be applicable in such scenarios. It is used in highly corrosive environments such as marine, chemical and aerospace industries as it has the property of maintaining its toughness over a range of temperature, however machining of this Monel alloy is relatively tough due to its characteristic work hardening properties. To tackle the mentioned issues, Abrasive water jet machining is used which is a widely known nontraditional machining technique. The process parameters and the response variables were chosen depending on the machine specifications, and parameter combinations were made using Minitab statistical software. The parameters and their interactions like the cut quality on the alloy, nozzle diameters effects, and water pressure were also studied. Response surface model and various statistical algorithms such as S-N ratio, ANOVA and regression equations were utilized for formation of the design of experiment, optimization of process parameters for the machining process were done using Grey relations. Reduction of surface roughness, maximization of Material removal rate while simultaneously reducing the cycle time for the operation was the primary objective. The results thus obtained indicates that the quality of cut was the most influential factor in the machining process followed by water-jet pressure value.
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