## Basic Elements Required For Electrodynamic Shaker Sizing

In order to select the proper electrodynamic shaker system size there several basic pieces of information to be assembled. Since all sizes of shakers have a force rating, the first piece of information required in order to properly size a shaker is the force required during the test process. In order to calculate the force requirement you will need two essential pieces of information.

- What is the moving mass? The moving mass includes the weight of the armature, any fixtures including head expanders and slip tables as well as the weight of the product being tested.
- What is the desired acceleration level?

The combination of these elements provides calculated force requirement of the shaker in order to perform the test.

## 1. What are the vibration test conditions?

- Mass of the product being tested.
- Mass of any fixturing
- Frequency range required.
- Maximum Acceleration required.
- Maximum peak to peak displacement required.
- Maximum velocity required.

## 2. Calculate the force requirement.

Calculate the force requirement for the required vibration test using the following formula.

F = (M_{1 }+ M_{2} +M_{3}) x A

F = Force (lbf)

M_{1} = Mass of Armature

M_{2} = Mass of Specimen

M_{3} = Mass of Fixture and head expander or slip table

A = Acceleration

**Example Calculation:**

Armature Mass = 66 pounds

Specimen Mass = 77 pounds

Fixture and head expander/slip table Mass = 99 pounds

Maximum Acceleration = 20g

**Important Note: **A common question we get involves the moving mass.** **Do not forget to include any mass that will be moved during the test. This includes the armature, headexpander, test article, slip table if in use and any fixturing required to mount the test article.

The required force would be calculated as

F= (66 lb. + 77 lb. + 99 lb.) x 20 g = 4840 force pounds

This calculation determines the minimum force required. In reality the required force would be **1.2 – 1.3** times the above calculation. So the minimum calculation is in fact 4840 x 1.3 = 6292 force pound minimum requirement.

**Note: certain test profiles require even more scaling due to the profile requirements. Please share your test specifications with your Dongling professional to determine proper shaker sizing.**

## 3. Select the Dongling Electrodynamic Shaker Model that meets your requirements.

To select the proper Dongling Technologies shaker model for your needs you can use the calculation you made in step 2 above and refer to the shaker specifications found on the Air Cooled Electrodynamic Shakers page or the Water Cooled Electrodynamic Shakers page on our website. Refer to the shaker specifications to find the first shaker that can produce the force required in the above calculation. For the example calculation you made in step 2 above the ES-30-370 has a sine and random force rating of 6600 force pounds. This is the first available size that will exceed the force requirements in the calculation.

Remember to consider your current and your future needs when sizing your shaker. Future needs may require a larger force and your selection based on current needs may be insufficient to meet the future specifications.

## Still need help?

Feel free to contact us by phone or email and we will be happy to assist you in selecting the appropriate size and options. Don’t purchase more than you need, but make sure you can meet your requirements.

Telephone: (616)583-8246