# redAnTS TUTORIAL: CSG Tool and Point Boundary Conditions

Rajesh Bhaskaran
Mechanical and Aerospace Engineering
Cornell University

This redAnTS tutorial solves a beam bending problem and in the process shows you how to

1. Generate a mesh using the CSG Mesh Tool.
2. Set boundary conditions at a point.

It is assumed that you are familiar with the introductory redAnTS tutorial. You need a license for the Partial Differential Equation (PDE) Toolbox in MATLAB to run the CSG Mesh Tool. The student version of MATLAB does NOT come with the PDE Toolbox. You need to purchase an additional license from mathworks.com. Public computers labs at Cornell have the PDE Toolbox. Also, the CSG Mesh Tool was developed in MATLAB version 7.0. We haven't had the time to upgrade it to later MATLAB versions. This means that in MATLAB version 7.4 or later, you'll get warnings about obsolete functions while running this mesher. We know it's ugly and not a good practice but you can ignore these warnings for now.

#### Problem Specification

Consider the beam in the figure below. There are two point forces acting on the beam in the negative y direction as shown. Note the dimensions of the beam. The Young's modulus of the material is 73 GPa and the Poisson ratio is 0.3. We'll assume that plane stress conditions apply.

We'll put redAnTS to work on solving this problem using FEA. We'll plot displacements and stresses for the beam and make comparisons with theory.

#### Solution Steps

We can use the same steps as in the introductory tutorial to obtain the FEA solution:

- Step 1: Start-up and preliminary set-up
- Step 2: Generate finite-element model
- Step 3: Specify inputs
- Step 4: Assemble and solve global system
- Step 5: Post-process the solution

Let's dive into step 1 without further ado.

Go to Step 1: Start-up and preliminary set-up