CUBICS » Sprint 014

Responsible: Sarah
Accountable: Ben
Consulted: Ben
Informed: Mike

What: Evaluate scope of task developing shaker mounting solution. Learn about the precedent in this testing. Consider how we may design a solution in a future task.

Why: We need a means of affixing a 3U CubeSat to the shaker armature in order to perform shaker testing (in the vertical orientation lacking a slip table). We need to establish weather this is feasible given the limitations of our system.

Resources:
1. 2U mounting solution: https://drive.google.com/drive/folders/1BYh78zX3MQ0rSeg7KxSm11n6B8hC-vYo
Someone previously developed a 2U mounting solution for the smaller satellites. It appears to be incomplete however there is some brief documentation detailing the design process. I have commented a few points in the document: https://docs.google.com/document/d/1DDt8PW8CEGl7I_C8iQ-FhkSif1ibSP6mgxf_VQEoQPk/edit

2. Blue book:
The blue book has advice on best practices for designing fixtures. Certainly read through some of the example solutions as they may give some reasonable insights.

3. Ex-Alta1 test report: https://drive.google.com/file/d/0B2zRSf1Lb9LGOTh6UUJmc1NPVlk/view?resourcekey=0-x0KfvmgwgrZWQWFoqw21YA
Scan through this test report from Ex-Alta1 to get an idea of what proper vibrational testing tends to look like. Note how large their shaker is and similarly how large the test deployer is. We do not have the same luxury with our little machine. This is why we need an additional part to interface the armature and the test deployer.

Considerations:

1. Mass:
I have calculated (but yet to prove) that we can likely shake about 8kg, perhaps 10kg with modifications, and still meet the required amplitude. Assume that any given 3U satellite will be about 4kg leaving us with 4kg to fix it to the armature. This is effectively our mass budget however ideally it should be lighter

2. Natural Frequency:
We test our satellites with vibrations in the range of 20-2000 Hz. This means that the mounting solution should have a first natural frequency higher than 2000Hz as to not resonate while we are shaking the satellites.

3. Interfaces
The mounting solution must interface with the shaker armature at one end and the satellite at the other end. The mounting solution may consist of 2 main parts, the rigid deployer like box that holds the satellite and the part that connects the box to the armature, or these parts may be merged in some capacity. I see developing a test deployed to hold the satellites as a separate task however we should consider this element as it too will take a large chunk of the 4kg we have to work with.