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.
Pseudo Velocity to SRS Acceleration Calculator
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.