Fixtures Reliability Test In Vibration / Impact Testing

Why make a fixture?

There are many kinds of electrical and electronic products in different shapes and sizes, so when doing vibration and impact tests, matching fixtures are usually designed for testing. The fixture is to firmly fix the test piece on the working surface of the vibrating table and transmit the vibration of the shaking table to the test piece. Its quality is also directly related to the quality of the test.

The purpose of vibration test fixture

When the volume of the specimen is relatively small and the shape is relatively regular, the specimen can be firmly fixed on the bushing screws of the vibrating table using screws and pressure plates.

But when the specimen is large in size and has complex and irregular shapes, this fixing method is obviously difficult. At this time, a specific fixture needs to be made, the specimen is mounted on the fixture and then the fixture is firmly fixed on the vibrating table. Therefore In fact, the fixture is the carrier that connects the test piece to the vibration table. Its function is to transfer the vibration and energy of the vibration table to the test piece without distortion.

What are the types of vibration test fixtures?

Since there are many types of test products or objects with different shapes, it is difficult for each company to use a common fixture to complete the test. Test engineers need to design it themselves. Here are some commonly used fixture shapes for reference:

ØL type clamp

The L-shaped clamp is suitable for multi-axial testing. It has the advantages of good rigidity and easy installation and removal when changing directions.

ØCube type fixture

The cube fixture is suitable for multi-axial vibration and impact testing of small components and can be directly fixed on the vibration table. The closed characteristics determine its high stiffness.

ØT type clamp

T-shaped clamps are similar to L-shaped clamps. Advantages: The structure is symmetrical, and the test piece can be installed on both sides in the vertical direction at the same time, so that the joint center line of the fixture and the test piece passes through the central axis of the table.

ØFlat type fixture

The function of the flat-type fixture is to connect the test piece to the vibrating table. Without such a plate, it is rarely possible to directly connect the test piece to the vibrating table for vibration or impact testing. In addition, this plate reduces wear on the bushings on the vibrating table and the risk of the bushings coming out of the table.

ØPlate fixture

The plate clamp is the simplest clamp, including wooden clamps and aluminum clamps. The plate clamp can also be used as an adapter plate, and multiple small clamps can be installed on it, which not only improves efficiency but also reduces the wear of the table threads.

ØTaper clamp

The tapered clamp is suitable for large specimens and can increase the effective surface area of the specimen. It adopts a rib shape to increase the stiffness to weight ratio and uses casting or welding forming processes.

ØExcessive rack type fixture

The transition rack type fixture is mainly used for testing of complete machine products. This fixture should be designed according to the shape of the test sample. Therefore, samples of different shapes have different shapes of clamps. The shape, stiffness and strength of the transition clamp should be as close as possible to the actual use of the sample.

Transmission relationship diagram of various parts of vibration