A product is measured on a shock tester in order to find the fragility to shocks. The procedure is as follows in 2 parts:
- First part: Critical velocity change, D V
Definition of the vertical line in the diagram
For shock absorption plastic absorbers are used to have short (1-3 msec.) elastic shock. After every drop both Acceleration in G and velocity change, D V is written down and set in to a diagram. First test is done from low drop height i.e. 50 mm. Drop height is slowly increased in I.e. 25 mm steps. Until the first sights of damages occur in the tested product. Drop height is closely connected to velocity change and the energy in a drop. The second last drop is then the critical energy for the product.
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Second part: Critical acceleration, A
Definition of the horizontal line in the diagram
The second part of tests is done on more than 1.6 x D V or drop height than the critical energy. The second part is done with another material as shock absorber. The material shall be able to create a plastic shock i.e. EPS. You start with a little area of absorber material and slowly adding the area until you reach the critical area of acceleration. In professional equipment a gas cylinder is used.