3 Steps to Successful Vibration Testing
March 23rd, 2020
Elite’s Environmental Stress Testing team has decades of experience planning and executing Vibration and Shock Testing programs. And as an independent testing laboratory, they have seen everything from small cable connectors to entire aircraft radome assemblies. Our team offers these 3 steps to prepare for and succeed on your next project:
1. Understand your product’s application and environment
Consider how and where your product will be installed to determine the scope of vibration testing. Vehicle-mounted products experience vastly different vibratory environments than aircraft or marine products. For exterior-mounted products exposed to the elements, temperature and humidity cycling combined with vibration may be appropriate. If you have compliance requirements, a “simulate” test will demonstrate a test item’s ability to withstand the test environment and continue operation. Alternatively, a “stimulate” test is intended to excite failure modes and find design weaknesses by “testing to failure.”
2. Choose the right vibration profile and levels
Real-world vibration data is always the best option and ensures accurate simulation of the intended application. If real-world data is not readily available, Elite is equipped to collect and analyze field vibration data using multiple accelerometers, video recording, and GPS tracking and precisely replicate it on our vibration test systems. Industry standards, such as MIL-STD-810, DO-160, MIL-STD-202, SAE J1455, and IEC 60068, offer guidance on choosing vibration profiles but they must be tailored for your application. Even when referencing an industry standard, it is important to develop a clear test plan that specifies the key test parameters, such as frequency range, acceleration (G) levels, test duration, and test item axes.
3. Design appropriate mounting fixtures
Mounting fixtures fasten test items to the shaker and must be designed to accurately transmit vibration energy to test items without dampening or amplifying vibration levels. This should be considered early in your planning process since it requires lead time for design and fabrication. Simple bar-and-clamp fixtures are adequate for some test items, but custom mounting fixtures are typically required to accurately simulate installed orientation and mounting interfaces. The fixture should align the CG of the test item with the center of the vibration table, especially for large test items, to prevent over-testing and stress on the shaker. The test frequency range informs material selection and fabrication methods since the resonant frequency of the fixture should be well outside of your test frequency range. Steel fixtures are lower cost and can be welded for low frequency tests, but aluminum is necessary for higher frequency ranges. Welding aluminum fixtures is an option, but due to the additional costs of stress relieving and secondary machining, bolted fixtures with keyed components, are the most cost-effective for many applications.
Elite now offers 7 vibration test systems to ensure projects are started quickly and completed on time. Our newest shaker features 25,000 lbf load capacity, 3 inch displacement, and a 36” square slip table. Most of our shakers are also equipped with chambers to combine temperature, humidity, and vibration exposure simultaneously. Our lab is equipped to meet our customers’ most difficult requirements and extreme parameters for test items small and large. Elite’s expert mechanical design team is ready to put their experience to work for you to design and build the best mounting fixtures for your application using our on-site machine shop and 3D printing capabilities.
Contact us or request a quote today to start your next Vibration and Shock Testing project with confidence. Our Vibration Testing Tutorial also provides valuable information to confidently prepare for your next project.