Vibration testing on an electrodynamic shaker is a standard part of product qualification, yet critical details are often overlooked. Many test failures and even false passes can be traced back to missing fundamentals.
Before you press “Run” on your next shaker test, take a moment to review these six key tips. They can help you understand why test results sometimes do not align as expected and could even change your outcomes, your results, and the way you approach testing.
1. Make Sure the Test Profile Represents the Real-World
Your test is only as good as the vibration profile you select. Sine, random and sine on random profiles each simulate different real-world conditions.
For example, a Power Spectral Density (PSD) profile derived from truck transportation often highlights low frequency damage risks, while a turbine operation sine sweep focuses on higher frequency behaviour. Choosing the wrong profile can mean missing critical failure modes or unnecessarily over stressing your product.
Always ask what environment you are trying to replicate and what standards you are testing against. The standards will often outline the profile required for specific tests. This could include transportation, storage, daily operation, or combined stresses. Aligning the test profile with a specific environment produces more meaningful and reliable results.
For more information on shaker profile design and accelerated vibration testing, follow the links provided to explore these topics in greater detail and gain deeper insight into improving your test results.
2. Fixture Design Matters More Than You Think
The fixture is not just a mounting bracket. It is part of the test system. A poorly designed fixture can introduce unwanted resonances, distort vibration transmission, or apply unrealistic loads to the test item.
Fixtures should be stiff, lightweight and well characterised. As a rule of thumb, the natural frequency should be at least three times higher than the highest test frequency to ensure adequate stiffness and test credibility.
Fasteners are equally important. Use the correct tensile strength bolts and torque them according to the manufacturer specification, as over torque can damage inserts, fixtures, or even the armature. Ensure the correct bolt length is used and avoid spacers wherever possible because they can negatively affect test quality.
For more information on fixture design, explore this blog on designing and building a head expander.
3. Control Strategy Affects Test Validity
Single point control is simple and widely used, but it rarely captures the full vibration response of a structure.
In one case, a single point control test resulted in a product corner fracturing because a board resonance was not properly monitored. More advanced approaches such as multi point control and notching help prevent over testing at resonances and better represent real world conditions.
Understanding how your shaker controller manages feedback is essential for producing valid and useful test results.
Please refer to the article on Advanced Control Strategies for Single Axis Vibration Testing.
4. Accelerometer Placement Is Critical
Accelerometer placement has a direct impact on measurement accuracy. Sensors positioned too far from the device under test or mounted incorrectly can produce misleading data.
Carefully select sensor locations and verify mounting methods to ensure reliable measurements. Sensors should be mounted as close as possible to the critical response areas. Flexible panels should generally be avoided unless the intention is to measure panel response.
Bolt mounted accelerometers typically use 2 to 4 Nm torque, while adhesive mounted sensors using epoxy resin provide a good balance between strength and vibration transmission.
To learn more about properly placing control and measurement accelerometers during shaker tests, click here for further insights.
5. A Pass Result Does Not Always Mean Success
A laboratory pass result does not automatically guarantee field reliability. Shaker testing is powerful, but it remains a simulation of real-world conditions.
To connect laboratory results with real world performance, translate a pass into measurable outcomes such as improved Mean Time Between Failures (MTBF), reduced warranty returns, and improved product durability.
Carefully analyse your data and investigate unexpected behaviour. The most valuable insights often come from anomalies.
Learn more by clicking the link to watch the full webinar on Quantitative Accelerated Life Testing Analysis, where you will gain insight into reliability analysis, practical challenges, and how to design effective accelerated tests for real-world applications.
6. Monitor Shaker Health
Your shaker is also part of the test system, and its performance can change over time.
Build a shaker health history. After extensive testing, run sine, random and shock profiles on an unloaded shaker and compare the results with historical baseline data such as commissioning measurements or post service measurements.
Any discrepancies may indicate suspension wear, armature issues, amplifier problems, or the need for servicing or recalibration. Monitoring shaker health helps ensure test integrity and prevents incorrect conclusions about your product.
At TANDM, we offer shaker servicing and health monitoring solutions under a service level agreement. Please feel free to contact us to find out how we can assist you.
Learn how predictive maintenance and remote diagnostics can enhance your shaker system performance by clicking the links in this sentence.
Final Thought
Shaker testing is not just about ticking qualification boxes. It is an opportunity to understand your product limits and behaviour. The more attention you give to the fundamentals, the more valuable every test becomes and the more confidence you can have in your results.
Do you have any additional tips to share? Let us know in the comments below.
