How would you test large vehicle for sinusoidal vibration

In summary, the conversation discusses how to perform a sinusoidal test on a large vehicle weighing over 40 tons. The speaker is confused about how the information on a graph was obtained due to a lack of a powerful testing device. They mention that there are vibration test facilities for large vehicles and suggest that the manufacturer may have their own facility or contract out to a test house. It is also mentioned that a Boeing 747 aircraft weighs more than 40 tons and that hydraulic actuators can apply enough force for most vibration testing. The conversation also references a static load test as an example of specialized test rigs.
  • #1
nortel
3
0
Hey, could anyone explain how you would preform a sinusoidal test on large vehicle (weight>40 tons). I have a graph from sinusoidal data, but i don't understant how they were able to obtain this information because there is not a powerful enough testing device.
 
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  • #2
nortel said:
Hey, could anyone explain how you would preform a sinusoidal test on large vehicle (weight>40 tons). I have a graph from sinusoidal data, but i don't understant how they were able to obtain this information because there is not a powerful enough testing device.

How much does a Boeing 747 aircraft weigh?

http://www.worldwide-aviation.net/index.php?option=com_content&view=article&id=164:delayed-747-8-set-for-pre-flight-shake-tests&catid=39:ac-manufacturers&Itemid=68

There are some vibration test facilities for large/heavy vehicles. What vehicle do you have data on? Perhaps that manufacturer has a large test facility including a vibration test area, or else contracts out to some large test house?


EDIT -- A Boeing 747 weighs more than 40 tons:

http://www.boeing.com/commercial/747family/pf/pf_facts.html

.
 
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  • #3
You can buy hydraulic actuators that will apply 10 or 20 tonnes force at frequencies up to 100 or 200 Hz "off the shelf". That's more than enough for most vibration testing. You don't need to apply a 40-tonne force to shake a 40-tonne structure by a measurable amount.

This is a static load test not a vibration measurement, but it give an idea what sort of test rigs are built for special purposes: (It also show how much aircraft wings can bend before they break, which might be a surprise!)
 
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  • #4
Thanks for the examples and the help, It makes sense to me now.
 

1. What is sinusoidal vibration and why is it important to test for in large vehicles?

Sinusoidal vibration is a type of mechanical vibration that follows a sinusoidal pattern or motion. It is important to test for in large vehicles because it can cause discomfort and potential damage to both the vehicle and its passengers if not properly addressed.

2. How would you simulate sinusoidal vibration in a testing environment for large vehicles?

To simulate sinusoidal vibration, a vibration test system is typically used. This system consists of a shaker or exciter, which generates the vibration, and a fixture that supports the vehicle. The shaker is controlled to produce a specific sinusoidal vibration frequency, amplitude, and duration.

3. What are some common methods for measuring sinusoidal vibration in large vehicles?

Accelerometers are commonly used to measure sinusoidal vibration in large vehicles. These devices measure the acceleration of the vehicle's structure and can provide data on the frequency, amplitude, and direction of the vibration. Other methods include strain gauges, which measure the strain on the vehicle's structure, and laser vibrometers, which use lasers to measure the displacement of the vehicle's surface.

4. How do you determine acceptable levels of sinusoidal vibration in large vehicles?

Acceptable levels of sinusoidal vibration in large vehicles depend on the specific vehicle and its intended use. Generally, standards and regulations set by organizations such as the International Organization for Standardization (ISO) or the Society of Automotive Engineers (SAE) are used to determine acceptable levels. These standards take into account factors such as human comfort, structural integrity, and component durability.

5. What steps should be taken if a large vehicle fails a sinusoidal vibration test?

If a large vehicle fails a sinusoidal vibration test, the cause of the failure should be identified and addressed. This may involve making design modifications, changing materials, or adjusting the vehicle's suspension system. The vehicle should then be retested to ensure that it meets the acceptable levels of sinusoidal vibration. Continuous testing and analysis should be conducted to monitor and improve the vehicle's performance and reduce the risk of future failures.

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