Cammthane recently received a request to manufacture a very large safety cover for a very expensive heavy piece of machinery:
Cammpro assisted by performing a Stress Analysis or sometimes called an FEA (Finite Element Analysis) to determine the most appropriate material to be used.
The machine in question is below:
The safety cover would be required so when the machine is kept in storage there would be a safety cover to protect the machine from being damaged, but the cover would have to have strict requirements:
- Withstand the weight of the machine of 1100KG.
- Not deform excessively so the machine would be compromised.
- Not damage the bottom face of the machine
First the 3D design was created in Autodesk Inventor:
Now the Stress analysis can be performed. With every stress analysis firstly, all conditions must be entered:
- Material: 3 below materials were selected for the analysis:
HDPE: High-density polyethylene
UHMWPE: Ultra-high-molecular-weight polyethylene
For this analysis the constraint of the part is a “Fixed constraint”, the face that will be in contact with the static object, in this case the floor:
3. Now the load can be applied, we know the weight of the machine in KG, but the load is measured in Newtons, where Newtons are a unit of force used in physics in relation to weight and mass. This measurement is used to see how much force a certain mass (e.g. the machine) is applying. To calculate the force in Newtons the calculation kg x 9.807 = N is used, therefore 1100KG x 9.807 = 10787.7N, which is now the “Force load” in a vertical direction.
4. Next is the mesh, models must be meshed before a stress analysis, the mesh will be made up of one or more forms of geometric elements, a mesh applies physics, with the understanding that things can change, and need to be taken into consideration during analysis. Proper meshing allows for accurate analysis. For any FEA to be successful, analysis is critical, and proper meshing is an important part of that analysis.
5. Now the stress analysis can begin
The results of the FEA produces a report that includes, Von Mises Stress, 1st Principal Stress, 3rd Principal Stress, Safety Factor, 1st Principal Strain, 3rd Principal Strain and Displacement. In this case the customers highest priority was Displacement in the vertical direction, the findings were:
Therefore HDPE was the most suited material with only 1.9mm displacement under the full load.
To see the stress test animation, click here:
YouTube Stress Analysis
The Material of choice was selected as HDPE and manufactured at Cammthane.
Firstly, the part was waterjet cut to rough out the part then finished with a CNC Mill. See below for the finished product.