# Pseudo Velocity to SRS Acceleration Calculator

#### Calculators and Tools

Pseudo velocity is a product of relative displacement and natural frequency. If you have the demand for pseudo velocity, you can use this free Excel calculator to calculate the equivalent SRS acceleration.

### Approximating Relative Velocity

In industries such as aerospace and seismic, test labs often perform complex shock tests using the shock response spectrum (SRS).

The SRS uses a theoretical series of single-degree-of-freedom (SDOF) mass-damper-spring oscillators to model a test item’s response to a shock event. It displays the absolute maximum acceleration of the SDOF oscillators at various natural frequencies in response to excitation. Although it is theoretical, the SRS provides valuable information about a test’s maximum dynamic load as a function of frequency.

Depending on the application, an engineer may also calculate the relative displacement or velocity during an SRS test. Velocity is directly related to product fatigue and is a good indicator of vibration severity. Displacement is beneficial for testing environments with low-frequency components, particularly in seismology and earthquake engineering.

As the SRS is a function of frequency, engineers can convert the acceleration data to displacement and velocity and vice-versa. The absolute acceleration and relative displacement of an SDOF system are easily calculable, but it is common to approximate relative velocity as a pseudo velocity. Relative velocity is more difficult to accurately calculate, and the pseudo velocity can provide more useful information.

#### Why Pseudo Velocity?

Test labs are most concerned about an excitation’s potential damage. SRS acceleration quantifies a shock environment, helping to identify how a system would react to an excitation. The pseudo velocity measures the severity of the shock event and indicates potential damage.

Pseudo velocity is a common requirement in naval applications and can be graphed as a pseudo-velocity SRS or a pseudo-velocity shock spectrum on four-dimensional paper.