Space Grant Consortium - University of Wisconsin - Green Bay

Shock
Mechanical shock, a physical shock, is the form of shock that will affect detector
structures. The definition of mechanical shock is the response of a structure to high
frequency, high magnitude stress waves that propagate throughout the structure as a
result of an explosive event. The nature of shock is transient, or very brief. The response
of the structure from the stress waves or shock pulse is a sudden acceleration. This
acceleration is measured with an accelerometer, which measures a shock pulse as a plot
of acceleration, in terms of gs, versus time.
A. Quantification of Shock
A shock response spectrum (SRS) is the method used for representing a
mechanical shock event. A SRS is a graphical representation of shock in terms of how a
single degree of freedom (SDOF) system responds to the shock pulse at a defined
amplification. It is a graph of the peak acceleration response of SDOF systems at each of
their own natural frequency.
An SRS is generated from a shock waveform using the following process:
1. Pick a damping ratio for your SRS to be based on and assume a hypothetical Single
Degree of Freedom System (SDOF), with a damped natural frequency of x Hz
2. Calculate the maximum instantaneous absolute acceleration experienced by the mass
element during (or after) exposure to the shock in question.
3. Plot this in g's (g's are standard, but pick any unit of acceleration you want) against the
frequency (x) of the hypothetical system.
4. Repeat steps 2 and 3 for other values of x, say logarithmically up to 1000x.
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