Carnegie Mellon Mechanical Engineering

Self-paced learning on the Web
FEM/ANSYS ## Test S1: Compression Unit      Structural Test #1: Analysis of a compression unit

Introduction: In this example you will be tested on the 2-D Truss element in ANSYS.

Physical Problem: The structure is mainly subjected to loading in the horizontal direction due to compressive forced. In this example we will consider only loading due to these forces, which are in the horizontal direction.

Problem Description: The tower is made up of trusses. You may recall that a truss is a structural element that experiences loading only in the axial direction. Units: Use S.I. units ONLY Geometry: the cross sections of each of the truss members is 6.25e-3 sq. meter. Material: Assume the structure is made of steel with modulus of elasticity E=200 GPa. Boundary conditions: The unit is constrained along X and Y directions at the bottom right corner and the top left corner.  Objective: To determine deflection at each joint. To determine reaction forces at the mounted corners. You are required to hand in print outs for the above. Figure: The units are as explained below, kept simple to expedite the test (all horizontal and vertical links are 5m long)  IMPORTANT: Convert all dimensions and forces into SI units.

·         Create the keypoints defining the joints for the truss.

·         Connect them with lines to define the truss links.

·         Define the Material Properties of the Steel Element (Elastic Modulus and Poison’s Ration are the important qualities)

·         Define the Element Properties as a 2D Spar Structural Link

·         Define the “Real Constants” of the linkage by setting the values for the Element Type for Real Constants. (Set the values for a Real Constant Set No. of 1 and a Cross Sectional Area of 6.25e-3) Mesh the truss such that each line is exactly one element. Apply Boundary Conditions (X and Y movement constraints on the upper left corner and the lower right corner, on the lower left corner there is a load of 6000N, on the upper right corner there is a load of –6000N. Solve List the nodal results of the analysis. (for both degrees of freedom) Plot the nodal deformation in the X direction. These are the results you should expect:

(The nodal displacements will be listed as follows) (The plot of the deformation will look like this) 