VM-WB-MECH-020

VM-WB-MECH-020
Modal Analysis for Beams

Overview

Reference:Any basic Vibration Analysis book
Solver(s):

Ansys Mechanical

Analysis Type(s):Modal Analysis
Element Type(s):Beam

Test Case

Two collinear beams form a spring mass system. The density of the longer beam is kept very low so that it acts as a massless spring and the smaller beam acts as a mass. The end vertex of the longer beam (acting as a spring) is fixed. The cross section details are as shown below.

Find the natural frequency of the axial mode.

Figure 22: Cross Section Details for Both Beams

Cross Section Details for Both Beams

Figure 23: Schematic

Schematic

Material Properties
MaterialE (Pa)νρ (kg/m3)
Spring1.1e110.341e-8
Mass2e1107.85e5
Geometric PropertiesLoading
Spring beam length = 500 mm
Mass beam length = 5 mm

Results Comparison

ResultsTargetMechanicalError (%)
Natural Frequency of Axial Mode (Hz)1188.61190.50.160