# Sensitivity Analysis

Sensitivity Analysis is the next step in the post processing of SnRD Post. The standard post-processing in SnRD offers the functionality to generate time domain displacement plots of each of the node-pairs of all the E-lines that are present in the model. The purpose of the Sensitivity Analysis is to study the root cause of rattle and/or squeak at each E-Line. Two main diagnosis functionalities are enabled in SnRD sensitivity analysis step and are listed below -
1. Determination of Relative Modal Contribution to squeak and rattle of complete E-Lines and as well as at specific points on each E-Line
2. Capability to check the effect of changing the percentage of modal contribution on the squeak and rattle performance
Sensitivity Analsysis tab is as shown below.
Below are the operations which can perform in Sensitivity Analysis tab -
1. Result File - drop down list to select the results file loaded in the SnRD Main Tab
2. Subcase Name - drop down list to select the subcase associated with the selected Result File
3. Modal Result File (h3d) - to select a H3D file containing the modal contribution results.
4. Calculation Type -
The sensitivity analysis is a two step process.
1. The first step is to calculate the Relative Modal Contribution of the required E-Line to be analyzed.
2. The second step is to observe the change in results when the modal contribution is varied but either including a certain mode or excluding it from result calculations with the help of Modal Sensitivity study. The relative modal contribution for a particular E-Line can be calculated and studied in two ways:
1. Study the modal contribution of the complete E-Line
2. Study the modal contribution of a particular node pair of an E-Line
The post-processing done on SnRD results provides the information about the E-Lines that are exhibiting undesired squeak and rattle behavior. In the sensitivity analysis the problematic E-Lines can be chosen for study. The Post-processing results also provide the information about which node-pair of an E-Line show the highest undesirable results.