Shock Test Machine Selection

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Shock test machine selection

Basic definition:

● Acceleration of gravity
the accelerated velocity in the surface of earth caused by gravity.
● Pulse duration:
Shock pulse rises from the reference value to the maximum value.
● Severity of shock test
It’s the combination of peak acceleration and nominal pulse duration.
● Velocity variation
The absolute value of sudden velocity variation caused by the implementation of specified acceleration.
● Basic pulse waveform

a. Half-sine pulse: Ideal pulse with the time course curve which is half period of half-sine wave.
b. Postpeak sawtooth pulse: Ideal shock pulse with the time course curve which has asymmetric triangle with short falling time.
c. Trapezoidal pulse: Time course curve is the symmetric quadrangle with short rising and falling time.

 

Computational formula

⊙ Half-sine wave:v=AD×10-3
⊙ Postpeak sawtooth wave:v=0.5AD×10-3
⊙ Trapezoidal wave:v=0.9AD×10-3

  △v=Velocity variation, unit m/s; A=acceleration, unit m/s²;
D=Pulse duration, unit ms.

 

Model selection:

Velocity variation of different pneumatic shock and collision test machines under the conditions of no-load and nominal load are indicated on the samples in the show room, customer can find suitable machines according to their own requirements.


For example: The weight of test specimen is 30kg, size is: 400x400mm, need to meet the half-sine test index of 100g, 11ms, according to the below formula:
Half-sine wave:v=AD×10-3
=2×1000(m/s²)×11(ms)÷3.14÷1000
           ≈7<12(The velocity variation of VASII400 under maximum loading),
So VASII400 shock test machine can meet the requirement of such test.