Carmine Salzano, PCB Piezotronics
Carmine Salzano, International Aerospace Manager, PCB Piezotronics Inc.
The Importance of Vibration Testing in Satellite Development is crucial and there are several reasons listed below:
• Qualification Testing: All spacecraft must pass minimum qualification and acceptance testing to be launched. Test profiles are determined by the launch provider.
• Ensures structural integrity and reliability: Vibration testing simulates the launch environment to ensure the satellite can withstand the stresses encountered.
• Identifies potential issues before launch: Early detection of design flaws or manufacturing defects reduces the risk of mission failure.
• Critical for mission success and longevity: Ensures the satellite operates as intended throughout its mission life.
Small satellites, such as cubesats, are mostly subjected to the same types of tests as larger satellites. There are many tests, but we will focus as above mentioned, on the various types of vibration tests. These tests, normally performed on the same large shakers traditionally used for testing large satellites, can now be performed on shakers of significantly smaller, cheaper and easier to handle, using a new technique. Not only will we describe this new technique in these pages, but also new vibration sensors technologies for various types of tests, as well as those performed in the usual excitations (sine, random, etc.) but also in particular environments such as high shock levels, microvibration measurements, and thermovacuum. Other type of test will be only mentioned: structural or modal test, acoustic stress test (executed with precision condenser microphones and accelerometer) and force limiting vibration test executed with force sensors that, through a NASA standard, regulate the procedure aimed at avoiding overstressing the satellite and its components. In particular in present paper, we will describe following new sensor’s technologies advancement representing today state of the art of measurement sensors technologies for satellite vibration test: Accelerometers for shock and pyroshock, Accelerometers for microvibration test, Accelerometers low outgassing for thermovacuum test, Accelerometers for vibration stress screening and new vibration excitation system for small satellite and cubesat.
Therefore main part of the article will consist of description of all new sensors technologies above listed and finally the new solution for vibration excitation shaker accompanied by a case study.
The most popular accelerometer technology is piezoelectric, in particular ICP® (IEPE) technology for satellite testing. In these accelerometers, which measure motion, the invariant seismic mass, ‘M’, is forced by the crystals to follow the motion of the base and structure to which it is attached. The resulting force on the crystals is easily calculated using Newton’s Second Law of Motion: F=MA. Thus, after a brief working principle, we will focus on the recent results achieved in the field of design and manufacturing of accelerometers suitable for the different types of tests mentioned with their related benefits.
After new sensors technologies part, we will describe the basics of satellite vibration testing and types of vibration tests, there will be a quick description of equipment and facilities used and testing procedure.
The vibration testing, as already above anticipated, is very important because it’s a simulation of launch and operational conditions to ensure satellite durability with objective to validate design, ensure durability, and predict performance under stress, reducing in this way risk of in-orbit failures and improves design robustness.
There is different type of vibration testing: sinusoidal, random, SRS (shock testing), acoustic stress. Testing procedure will be also briefly reported as well as equipment and facilities used: shakers and controllers, test fixtures and sensors. Each of these 3 main component’s designs of test and measurement test will be summarized.
The new vibration excitation solution consists to streamline CubeSat vibration testing with a new CubeSat test fixture which provides a broader standard mounting fixture to meet the standardized sizing of 1U, 2U, and 3U CubeSats. With the common fixture base that is built to interface directly with the vibration shaker, the user can quickly mount up to 3U size satellites in horizontal or vertical configurations for critical vibration qualification and acceptance testing based on NASA or other standards to ensure survivability during launch. Installing and configuring this new unique and dedicated shaker fixture is easy using included screws and tools. The simple removal also allows the shaker to easily be used for testing of sub-assemblies mounted either directly to the shaker, via head expander, or with optional slip table for additional component level vibration testing.
The benefits of this new solution are:
 Supports the mounting of various size CubeSats (up to 3U) to the shaker in different orientations
 Includes lightweight magnesium mounting fixture, dummy payloads, mounting accessories, and a heavy-duty case
 Simplifies qualification testing of CubeSats to NASA testing or other standards