Vibration Test Fixture Design And Solution
Vibration testing is an indispensable checkpoint in the product development process. Due to the wide variety of sizes and shapes of vibration test fixtures, a test fixture survey should be conducted before vibration testing to ensure that the structural characteristics of the test fixture do not introduce uncontrollable resonances into the test setup. If a problematic resonance is found, the test fixture should be modified. Make the resonance outside the frequency range of the test or print the resonance to minimize the impact on the test.
The test item is a small electrical component clamped onto a 5×5×12 rectangular aluminum plate. These plates are then mounted on a clamp that is permanently bolted to the shaking table. The first design of the fixture is a welded box structure of 38 thick welded aluminum plates, as shown in Figure 1. Due to the severe resonance below 1000 Hz, the "g" level on the test item is more than 10 times the value measured by the shaking table accelerometer, so the test cannot be performed.
Figures 3 and 4 show the design before and after this scenario, respectively.
If you are interested in our vibration test fixture design,
Please send us your enquiry via the Fixture Design form and we will be happy to assist you.
Common problems in fixture or vibration test fixture design
1.Fixture design does not match
Problem: The design of the fixture is not consistent with the shape or mounting point of the test item, resulting in misalignment and potential damage during testing.
2.Insufficient connection and fastening
Poor or improper tightening can cause test items to fall off, compromising the integrity and safety of the test.
3.Resonance and amplification
Inadequate fixture design can cause resonance and vibration amplification, affecting test results.
4.Test Item Overloading
Overloading the fixture with a test item that is too heavy or too large may result in structural damage or fixture failure.
Case and solution
Case 1The test item is a small electrical component clamped onto a 5×5×12 rectangular aluminum plate. These plates are then mounted on a clamp that is permanently bolted to the shaking table. The first design of the fixture is a welded box structure of 38 thick welded aluminum plates, as shown in Figure 1. Due to the severe resonance below 1000 Hz, the "g" level on the test item is more than 10 times the value measured by the shaking table accelerometer, so the test cannot be performed.
Solution
Redesign the fixture shown in Figure 2. The fixture is a solid magnesium cube with holes drilled in it to reduce weight. In addition, more fixing bolts are used to secure the shaking table. The resonance frequency of this new fixture was increased by more than 2kHz, and no testing difficulties were found.
Case 2
In this test, the sample is mounted into a cubic aluminum fixture. The fixture is then secured at four points to a 14-inch thick aluminum adapter plate. The transfer plate is fixed to the spring at four other points and resonates violently.Solution
There are two solutions. The fixture can be redesigned so that it is bolted directly to the shaking table, using more than four bolts if possible. The second is to redesign the adapter board. It is made of magnesium about 1 inch thick. It is secured to the shaker using all 13 vibrator connection points on the shaker. Additional bolts were added from the fixture to the plate.Figures 3 and 4 show the design before and after this scenario, respectively.
If you are interested in our vibration test fixture design,
Please send us your enquiry via the Fixture Design form and we will be happy to assist you.
