ASTM D4728 Standard Vibration Test Equipment with Vertical and Horizontal Table

Introduction:

The working principle of the electromagnetic vibration exciter is similar to a loudspeaker whereby electrical conductor is moved by the action of electromagnetic force in the magnetic field. The force to accelerate the moving part is generated by the balance between driving current and magnetic flux. Therefore, by controlling the driving current, one can control the vibration generator.

Features:

• Dual magnetic structure;
• Frameless armatures;
• Pneumatic load support;
• Rugged trunnion design with air isolation;
• Active armature suspension system;
• Small waveform distortion, high carrying capacity, good guidance quality;
• Protection functions for safety interlock;
• Good compatibity with slip table head expander, climatic test chamber, air isolation mounts, etc.

Calculate Formular for Exciting Force:

Specifications:

How to select a Vibration Testing Equipment:

1. Determine the Frequency Range of the test and the extreme Peak motions (Acceleration, Velocity and Displacement) from the Test Specification. Depending upon the type of test (Swept Sine, Random, or Classical Shock for example) you will perform different calculations to accomplish this.
   
2. From the Device Specifications determine the mass of the device under test (DUT) and the dimensions of the mounting surface required to bolt the DUT to a shaker table with its center of gravity (CG) over the table’s center. This may require use of a head expander and/or other mounting fixture. Determine the mass of such additional hardware including all mounting fasteners.
   
3. Look at the Shaker Specifications of a trial system. Verify that the mass of the DUT and any mounting fixtures are less than the shaker’s rated Maximum Static Payload. Verify that the DUT (or its mounting hardware) can be bolted to the shaker’s armature or head expander. Add the Effective Armature Mass and head expander mass to the DUT mass and the mass of any mounting fixtures and fasteners and any accelerometers mounted to the DUT – this is the Total Moving Mass that must be moved by the shaker during the test. Multiply the Total Moving Mass by the Acceleration determined in step one to calculate the Force required. Verify the determined test Frequency Range, Force, Peak Acceleration, Peak Velocity and Peak Displacement required by the test and DUT are all less than the corresponding performance ratings of the selected shaker system. If this is true, the selected shaker is acceptable. If not, a more powerful shaker is called for.

Detailed Picturers: