1. ADVANCED METHODS IN MECHANICAL DESIGN
Master's degree in Mechanical Engineering
TV stand design
Prof. Ing. F. Campana
Training exercise: a TV stand design
Students: Ilaria Ghezzi Leonardo Molinari Simone Paglia

2. Specifications: functions to be performed:
Product definition: TV stand
Product category: Domestic use forniture
Customer specifications: the customer requires the design of a TV stand for 32'' to 46'‘ televisions. The stand should be designed and built with resistant materials; It must be available in different colors: black, metallic and white. The cost must be in line with the stands currently available on commerce. There must be no sharp edges. The support should be placed on the ground and the TV's height should be adjustable to approximately one meter from the ground. It must be possible to hide the wires. It must be realized by the use of tools and machinery already available in the company.
functions to be performed:
Hold the TV
Not fall if bumped slightly
Have a modern look
Hide the wires connecting the monitor
Most important external properties:
Aesthetics
Safety
Manufacturability
Cost
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3. Requirements
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4. Interconnection between the external properties:
○ low
● high
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5. Use of CAD:
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6. Cable cover TV anchor that allows the adjustments
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7. This project is divided in five parts:
ANALYSIS OF THE OPTIMAL GEOMETRY: static study of displacement and stress applying 245N (assuming a maximum weight of the TV equal to 25Kg). By varying the thickness and the radius of curvature, different configurations are compared in order to find the best constructive solution.
STRUCTURE REACTION TO EXTERNAL DISTURBANCES: a misuse is simulated by applying a frontal force and a twisting moment.
MATERIAL ANALYSIS: Alluminio 6061 VS Policarbonato
TOPOLOGICAL OPTIMIZATION: using the software INSPIRE.  
VERIFICATION OF ABSENCE OF BUCKLING INSTABILITY: Buckling phenomenon is to be avoided.
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8. MATERIAL:
Aluminum 6061: main alloying elements are silicon and magnesium - EN AW This possesses good machinability, good mechanical strength and good resistance to corrosion ₁. 1:
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9. ANALYSIS OF THE OPTIMAL GEOMETRY:
HyperWorks v14.0 – Student Edition – OptiStruct
A first try geometry has been realized on SolidEdge and saved in STEP
This first geometry, with 15mm tickness and 30mm of curvature radius, has been imported in HyperWorks
The geometry has been cleaned using the command “autocleanup”
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10. MESH 1: The first 2D mesh has been built using 10mm quad elements
To adjust the mesh is possible, at first, to choose the number of elements for each side by clicking on the number between the yellow dots. The target is to get the most uniform mesh possible in order to create, in the next step, a good 3D mesh
Changing the number of elements is possible to change the local mesh density
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11. The 3D mesh is built using the command “tetramesh” – “Volume tetra”
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12. To delete the 2D mesh you must do:
NOTE:
In order to make a 3D study, the 2D elements must be deleted. If they are not deleted OptiStruct will show this error:
<<  *** ERROR # 2372 ***  No PSHELL properties exist in the bulk data >>.
To delete the 2D mesh you must do:
Delete elements by config
Then the 3D mesh must be checked using the check elements command.
tria3
quad4
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13. In order to put the forces in the right position, two
connecting beams are built.
ASSIGNMENT OF PROPERTIES AND MATERIAL:
The chosen material is alluminium6061,
is important to put only two values between E, G and NU.
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14. Load analysis:
Constrains are assigned to the base (Load Collector 1) Displacement is blocket along all directions: x, y, z (dof1, dof2 e dof3).
Then, forces are assigned (Load Collector 2). The total force has to be split along the nodes
Note that in the Card Edit you must specify:
The analysis type (Linear Static) and the variables involved (SPC and LOAD)
The output that you want to display (Displacement and Stress)
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15. These are the analysis output: DISPLACEMENT :
Finally the analysis is executed using OptiStruct specifying the input file and the export options: all, run options: analysis e options: -optiskip.
These are the analysis output:
DISPLACEMENT :
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16. ELEMENT STRESSES (VONMISES):
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17. MESH 2: A second mesh is built using 8mm elements in order to get a more precise analysis.
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18. LOAD analysis:
With the same loads applied the result with the second mesh is more precise
DISPLACEMENT:
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19. TENSIONE:
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20. GEOMETRY VARIATION: thickness has been decreased to 8mm
MESH COMPARISON:
Mesh a 8 mm
Mixed mesh 4/8 mm
4 mm
8 mm
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21. Mesh a 8 mm Mixed mesh 4/8 mm Training exercise: a TV stand design
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22. RESULTS: DISPLACEMENT Mesh a 8 mm Mixed mesh 4/8 mm
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23. STRESS Mesh a 8 mm Mixed mesh 4/8 mm
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24. SAFETY FACTOR X :
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25. REACTION TO EXTERNAL FORCES:
We simulate the possibility that the TV support is used inappropriately
1st CASE: twisting moment (two 100N forces with different direction).
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26. Results:
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27. 2nd CASE: 150N force pushing the TV stand
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28. DIFFERENT MATERIAL TEST: Polycarbonate.
Advantages :
less weight (6,6kg)
cheaper
DIFFERENT MATERIAL TEST: Polycarbonate.
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29. TOPOLOGICAL OPTIMIZATION:
Using the software INSPIRE the topology of the element, splitted in design and non-design bodies, has beeh optimized.
Partition 1
Partition 2
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30. Definition of forces and constraints for the optimization of the structure.
The frist optimization was carried out by minimizing the mass.
Partition 2
Partition 1
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31. The second optimization was carried out by maximizing the stiffness
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32. Construction of geometry by PolyNURBS.
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33. Creation of the optimized shape by Solidedge
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34. STRUCTURAL CHECK 1st CASE: considering the TV weight
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35. 2nd CASE: TV weight and an addictional external force
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36. BUCKLING ANALYSIS: There is no instability.
There is no instability.
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37. CONCLUSIONS
Following the various optimizations we chose to create an item excavated according to the optimized profiles, which maintains an attractive appearance and modern aspect.
Thick 15mm
Weight 25kg
Thick 8mm
Weight 15kg
Thick 8mm
Weight 6kg
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