Introduction
The Structural subsystem is primarily concerned with designing and eventually constructing components that are safe and durable to withstand elements to which they will be exposed, such as the launch loads.
Ensuring that the final designs are machinable and fulfilling the needs of our mission while taking into consideration the limited available space of a 3U CubeSat nanosatellite, is a real challenge that intrigues an engineer.
Thus, the following points must be carefully planned:
- preparing reports
- preparing designs and drawings (CAD)
- selecting appropriate construction materials
- constantly communicating with the other subsystems
- calculating margins of safety (FEM)
But most importantly, the key for working in the Structural subsystem is trial and error. Improving the design and it’s robustness is based on experimenting with different configurations until delivering the desired final product.
Materials
When it comes to materials the following 3 points must be taken into consideration:
- Desired strength of the material, based on the external loads
- Space grade materials
- Machinability of the material
Assembly
The final assembly consists of the:
- Frame, will be purchased from EnduroSat
- PCBs stack
Payload Container, which is designed by our subsystem
Design
The design of our in-house components is based on the needs of different subsystems.
Payload Container
Goal is to protect and to contain the experiment under the conditions that will allow it to be executed smoothly. The payload container will contain atmospheric air at 1 atm.
To maintain the pressure that ensures cell survival, gasket sealings will be installed on the opening interfaces and check valves will be used to regulate the internal pressure.
Unibody
The safe integration of the payload’s components in the payload container is important. Thus a unibody structure is designed to secure the following:
- the microchip, on which the experiment will be conducted
- the microscope that will record the results
- the nutrient as well as the waste tankÂ
Our subsystem should keep the chip focused on the microscope so that high quality images can be obtained.
Finite Element Analysis and Calculations
To test our designs and final assembly we must run FE analyses for the following cases:
- Quasi-static analysis
- Modal analysis
- Random vibrations analysis
- Bolt analysis (hand calculations)
- Pressure analysis (payload container)
- Leak rates analysis (payload container, hand calculations)
Our final FE model should be justified using the mesh convergence method. The delivered margins of safety will certify AcubeSAT.
