MOLA Random Vibration Input Specification

Input Spec for the Finite Element Model

This page shows what the input specifications for MOLA are in both tabular and graphical form. These inputs are specific for the MOLA instrument, which is being launched on a Delta II expendable launch vehicle (ELV).

There are two types of inputs, Acceptance and Protoflight (see the definitions page).

Acceptance Level Input

The first table shows the Acceleration Spectral Density (ASD) as a function of frequency. (Practically any quantity squared and divided by frequency is a spectral density, commonly called the Power Spectral Density--hence, PSD on all my charts.)

The usefulness of this quantity is that if you take the square root of the area under the curve, you get what we call the Root Mean Square value of the acceleration, usually written as Grms. This is just a statistical calculation of the acceleration that a body subjected to random vibration might see.

The table above is shown here on a log-log plot.

Input Spec

Protoflight Level Input

The same description applies to the protoflight input as to the acceptance input.

Protoflight Input Spec

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Goddard MeatballThis page is maintained by Ryan Simmons, at Ryan.Simmons@nasa.gov.
This page was last updated on January 11, 1996.