Prisms and Cubes
Prism and cubes are vibration shakers’ ancillary equipment.
Almost all vibration tests should be performed along 3 orthogonal axes while the shaker vibrates just in one direction. The axis can be moved by rotating the item and mounting a slip-table, a prism or a cube to the shaker. A traditional technique uses also the so called T or L fixtures, but our experience in vibration tests suggests that other structures like L and T fixtures alter in most of cases the vibration test by unwanted resonances.
A Cube has 5 faces that can be used to fix many items at the same time along different axes. Due to the fact that the mass of a cube rises very rapidly with the dimension, it is possible to use this solution only on small items.
The prism can be considered as a substitute of the slip table. Two opposite faces with the same inserts pattern can be used to test the items. The prism can be used to perform the in-plane (horizontal) axis while the out-of-plane (vertical) axis has to be performed fixing the items directly on the shaker armature or on an expander.
Both cubes and prism are standard structures which are very easy to mount and use.
The possibility to perform a test along 3 orthogonal axes without removing it is the main advantage of a cube.
The prism can reach a larger useful dimension compared to a cube by giving up 3 mounting faces of 5.
The remaining 2 opposite faces can be used to test 2 items at the same time.
The structure of the prism is very rigid and can be used at very high test frequency.