# Simcenter 3D Solutions Pre-Stressed Modal Analysis of a Guitar String tutorial - Part 1/4 - Background

2022-07-26T19:45:11.000-0400
Simcenter 3D

## Summary

In this tutorial, a simple simulation of a guitar string will be used to illustrate the process of performing a prestressed modal analysis in Simcenter 3D. This tutorial is divided into 4 parts: 1. Introduction and equation for hand calculation 2. Guitar string Geometry creation and setup SIM and FEM files 3. Mesh and assign material properties to Guitar string 4. Apply boundary conditions, solve and postprocess the model

## Details

In this tutorial, a simple simulation of a guitar string will be used to illustrate the process of performing a prestressed modal analysis in Simcenter 3D.
This tutorial is divided into 4 parts:
1. Introduction and equation for hand calculation
2. Guitar string Geometry creation and setup SIM and FEM files
3. Mesh and assign material properties to Guitar string
4. Apply boundary conditions, solve and postprocess the model

Part 1: Introduction and equation for hand calculation

The stress state within a structure can have a large effect on its normal modes. It is therefore important to capture these stress stiffening effects when performing a modal analysis. In this tutorial, a simple simulation of a guitar string will be used to illustrate the process of performing a prestressed modal analysis in Simcenter.

The simulation will be performed on the G or 3rd string of a guitar with a scale length (distance between the nut and bridge) of 25.5in (0.6477m). The string is made of steel and has a mass of 1.428e-3kg/m. At standard tuning, the string has an open frequency of 196Hz

The pre-tension required in the string to produce a frequency of 196Hz can be calculated using this equation:
t=m(2lf)^2
Where t is the tension
m is the string mass per unit length
l  is the scale length
f is the frequency in Hertz

Therefore:
t=1.428e-3(2(0.6477)(196))^2

t=92.05N

With the required pretention known, the Simcenter 3D simulation can now be performed.

Please follow Part 2 - Guitar string Geometry creation and setup SIM and FEM files

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