# Metal Connector Analysis

The metal connector is widely applied in mechanical engineering. As shown in the figure below, a typical connector has an elbow shape, the back surface is welded onto another bulk structure, and a circular hole, allocated at the extended area, can be connected with bolts. The dimension and working loads are shown as well in the figure. Now we need to know the deformation and stress distribution, which is essential to understand and optimize such part, for example, to reduce the stress concentration in the critical area.

This study can be conducted using simulation software WELSIM. If you have installed WELSIM v1.0, a CAD file called “standHalf3d.step” is included in your “data” folder.

## Problem Description

- **Material:** Young’s modulus: E = 200 GPa, Poisson’s ratio u = 0.33

- **Loads:** 
  1. Hole area stands a vertically downward force F = 2 kN. 
  2. Exterior surface stands a shear pressure P = 36 MPa.

- **Constraint:** The back surface of the connector is fully constrained to denote welding.

**Reminder:** WELSIM is dimensionless; user ensures the consistency of units.

### Keynotes:

Due to the symmetric geometry and loads, we use only a half part of geometry for the following analysis. The displacement boundary conditions will be imposed on the plane of symmetry.

### Start WELSIM

There are two methods in starting WELSIM application, user can choose either one of them.

1. Double click the desktop shortcut icon of “WELSIM v1.0”
2. Select from Windows “Start” menu: [Start] → [All Programs] -> [WELSIM] -> [WELSIM v1.0]

After starting WELSIM, the main window shows up. Clicking the “New project” toolbar button, we create a new FEM project with essential objects in the tree window.

### Define Material

Although the application provides a predefined “Structural Steel” material, we create a new material here to better know the material building process. Clicking the toolbar button “Add Material”, we insert a new material object to the material project. In this analysis, we define “Young’s modulus” and “Poisson’s ratio” to 2e11 and 0.3, respectively. Clicking “OK” button, we save it to the database.

### Import Geometry

Clicking the ”Import” toolbar button, we read a *.step format CAD file into WELSIM. In this example, we import “standHalf3d.step”, which is in your installation/data folder.

### Mesh

WELSIM v1.0 uses a fully automatic meshing scheme; the user can control the mesh density and element type between Tet10 and Tet4. In this example, we set “Maximum Size” property to 2, and other properties remain the default value. Clicking the meshing toolbar button, we generate Tet10-based mesh. The statistics data such as number of nodes and elements can be reviewed at properties of Mesh Group object:

### Impose Boundary Conditions

Now we impose four boundary conditions:

1. **Pressure:** Clicking “Add Pressure” toolbar button, we define the imposed area and pressure magnitudes at properties window. Imposing the pressure -3.7e7 on the Y direction on the exterior surface.

2. **Force:** Clicking “Add Force” toolbar button, we impose this concentrated force on the circular surface with a magnitude of -2e3 on Y direction.

3. **Constraint:** Clicking “Add Constraint” toolbar button, we impose this constraint on the back surface of connector.

4. **Displacement:** Clicking “Add Displacement” toolbar button, we scope it to the plane of symmetry, and define displacement on Z direction as 0.

### Solve

Simply clicking the “Compute” toolbar button, we start to solve the model. The solving should be done quickly.

### Evaluate Results

WELSIM v1.0 supports displacement, stress, and strain results. Each type of result supports different directions or components. Here are major results we are interested in:

1. **Total Deformation**

2. **von-Mises Stress**

3. **von-Mises Stress with Mesh and Deformed Shape**

### Conclusion

Once we know the deformation and stress results, the analysis of a metal connector is almost done. We obtain the maximum von-Mises stress 9.245e8, which occurs at the elbow corner. Combining the yield stress of the material, we know if this connector is well designed, and how to optimize it.