Why Do We Need to Perform Vibration Test?

If the prototype cost of our product is relatively small or if development time of our product does not really matter, due to no competition, then we may consider the vibration testing is not really relevant. But if our product is part of vital system in automotive where development time is getting shorter and crucial, or part of vital system in aerospace where prototype cost is relatively expensive and where safety has become very big issue, then having a vibration testing system may be considered as vital investment.

In automotive industry, the development time of new product is squeezed to be even shorter and shorter due to competitive market. The launching and delivery date of new product are key points, not only for marketing division, but also for production, procurement, even the quality division.

Automotive industry is like a big and long production supply chain, where all are somehow directly or indirectly linked to each other.

In automotive industry, the prototype of a new product normally shall go through an extensive long durability test, by continuously driving it through proving ground track or even going through real life environment.

This entire process of durability test may spend very significant period compare to entire development time.

The problem comes when one of component fails during this durability test. Should we repeat the whole process of durability test?

Should we postpone the delivery date? It will be very difficult and it may become a significant loss to postpone the delivery date, since the new production tools may have been prepared by engineering team, the new component from the suppliers are already in the inventory, and the previous automotive model may not be produced anymore due to no more component ordered from suppliers.

But is it possible to just proceed with production and do recall once the problem is resolved? Is it safe to do this?

In aerospace industry, the pressure of development time may not be bigger than automotive industry. But it does not mean there are no challenge available here.

Unlike automotive industry where we can see many prototype units produced during prototyping event, prototype cost in aerospace industry is much more expensive. Beyond that, compare to automotive industry, safety issue is considered more dominant in aerospace industry.

Even though most of the system in aerospace product are designed with redundancy, but still a very low probability of failure during flight test is expected.

All these challenges have been pushing the design engineers and testing engineers in automotive and aerospace industry to minimize the component failure during automotive durability test or flight test in aerospace industry.

How to minimize the component failure during automotive durability test or flight test in aerospace industry?

One of the ideas is to bring the actual durability or flight test environment into a laboratory scale test. This laboratory scale test is applicable at component level, sub system, or even whole automotive unit.

Below are most common types of vibration testing system that available:

Electrodynamic Shaker

This is the most common type of vibration testing system used by many testing laboratories.

An electrodynamic shaker is basically an electromechanical transducer that converts electrical current into dynamic mechanical force that used for vibration testing. This energy conversion is done by providing electrical current to both field coil and armature coil inside the shaker body.

The advantage of this type of vibration testing system is its capability to run at high frequency.

By having this capability, electrodynamic shaker has the flexibility to run many types of vibration test specification, especially the one having high frequency content.

On the other hand, the challenge of using this type of vibration testing system will be in the displacement capacity.

Some of vibration test specification needs high displacement capacity, especially the one that running dominantly at low frequency range.

Electrodynamic shaker manufacturer tries to overcome this challenge by designing a special Long Stroke type of electrodynamic shaker which is able to handle 4-inch displacement (peak to peak). 

Hydraulic Shaker

This type of vibration testing system can be considered as the second most common vibration testing used by testing laboratories.

Unlike electrodynamic shaker that directly convert the electrical current into mechanical force, hydraulic shaker uses hydraulic pump (Hydraulic Power Unit, HPU) to produces hydraulic pressure and convert this hydraulic pressure into mechanical force that used for vibration testing.

The advantage of this type of vibration testing system is its displacement capacity which can even go up to 8 inch (peak to peak) or even higher. This makes this type of vibration testing system quite useful for vibration test specifications that running dominantly at low-frequency range.

On the other hand, the challenge of using this type of vibration testing system will be in its frequency range.

A hydraulic shaker may not be able to run vibration test specifications with high-frequency content. In addition, using hydraulic oil as one of the main component creates another additional challenge from the maintenance aspect. 

Mechanical Shaker

This type of vibration testing system is using simple mechanical eccentric cam concept to produce vertical motion while controlling the frequency by using the motor rotational frequency.

By using this simple technology, this type of vibration testing system can be produced at a relatively low cost. But due to its simplicity, this vibration testing system is not able to perform relatively more sophisticated vibration test specifications.

Unlike an electrodynamic shaker or hydraulic shaker, we may not be able to run a sine sweep test or random test profile by using this shaker.

With a different range of equipment available for a different variations of environment testing, AscendTech Group had all systems that are designed to meet the requirements of endurance testing and offer superior performance as well as reliability. With a wide range of standard and optional fittings, there is sure to be a solution for every individual’s needs. With our wealth of technical expertise, our team of engineers is able to specially tailor solutions in the event that a standard solution is not available.