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DADiSP / SRS 2.2


Shock Response Spectrum Module

The Shock Response Spectrum, or SRS, is used in modeling a mechanical component as a series of single degree of freedom (SDOF) spring-dashpot subsystems each with a constant damping ratio and varying natural frequency. Each spring-dashpot subsystem is considered a 2nd order linear system and is converted into the digital domain. The absolute maximum response of each spring-dashpot subsystem is returned as the SRS result for the corresponding natural frequency of the subsystem. A plot of the absolute maximum responses for all the natural frequencies is the Shock Response Spectrum.

Multiple Analysis Methods

To calculate the SRS, each analog 2nd order spring-dashpot subsystem is converted into the digital domain. DADiSP/SRS DADiSP/SRS Half Sine Analysis supports three industry standard methods of performing this transformation: the Impulse Invariant technique matches the impulse response of the analog system with the digital model; The Ramp Invariant (Smallwood) technique, the most common approach and recommened by the ISO 18431-4 Standard, matches the ramp response of the analog system with the digital model; and the Bilinear Transform matches the frequency response. In addition, the damping ratio or Q factor for the spring-dashpot network can be specified.

Octave or Linear Natural Frequencies

The natuaral frequency range of interest can be specified in octave, fractional octave or linear bands to produce comprehensive SRS results. Whole octave and 1/N fractional octave bands provide SRS information over a wide natural frequency range with a minimum of computation. Linear frequency ranges are useful to produce high resolution SRS results for a narrow band of frequencies. The Absolute Max, Max Magnitude, Min Magnitude, Positive or Negative responses can be calculated. Once DADiSP/SRS Hardcopy computed, any SRS can be plotted with linear, log or log-log axes.

Fully Integrated

The SRS module is fully integrated with DADiSP to provide a complete shock analysis, display and processing environment. The DADiSP/SRS user interface is dialog based, eliminating the need to memorize argument lists or formulas and allows quick recall of previous SRS calculations. The SRS results are automatically displayed in a DADiSP window and can be saved for further processing by DADiSP or other programs.


DADiSP/SRS requires DADiSP 6.5 B01 or higher. Contact us for information about updating your current version of DADiSP.

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