Torsion of a racing car aerofoil.
An aerofoil is manufacturing from a carbon fibre reinforced polymer skin thickness 1.5mm with the geometry, lengths and areas given in the accompanying assignment XL spread sheet containing a corresponding SET No. ranging from 1 to 14.
use SET No 6.
A schematic of the cross-section is shown in fig A1. Using this information complete the following tasks stated below and answer the questions at the end of the tasks.
| Position | Length (mm) |
| AB | |
| BC | |
| CD | |
| DE | |
| EF | |
| FG | |
| GH | |
| HA | |
| CG |
| Area | Size (mm2) |
| ABH | |
| BCGH | |
| CDFG | |
| DEF |
Table A1, for your actual lengths and areas see your set number in the spreadsheet at the appendix.
Assume for the skin the following properties, Mean E fibre = 350 GPa, volume fraction = 65%, design strain 0.5%, and effective length is 1.6m.
Task 1 (40%)
Assuming the car can achieve a maximum speed of 220 mph with a lift coefficient of 1.6 for the aerofoil and the centre of twist is approximately is 15% of the chord length AE;determine the maximum angle of twist and shear stress induced in the aerofoil for this case.
Task 2 (10%)
The actual aerofoil however has closed ends with a small plate of the same material. Estimate how this will change your predicted answer and indicate the positions along the length were this is most affected using a simple sketch.
Task 3 (25%)
If under race condition the section is subject to an impact at the mid-point between the end plates which damages section FG. Estimate the increase in angle of twist and the maximum induced shear stress due this impact.
Torsion of a racing car aerofoil Supplementary questions
- If the aerofoil was manufactured from aluminium comment on how the behaviour of the aerofoil would react to the conditions in tasks 1 to 3 inclusive (10%)
- Describe how the “centre of twist” affects the loading (5%)
- Describe briefly how the composite part would be joined and how you could estimate the stress in the adhesive. (10%)
LOs for this work are as follows:
| Demonstrate a comprehensive understanding of the scientific principles of mechanical and related engineering disciplines (US1m |
Demonstrate an awareness of developing technologies related to mechanical engineering. (US4m)
Submission method
On completion of your task you will need to upload your solution via the moodle link provided by your module tutors.
Appendix
| Position | Length(mm) | DIMENSIONS | |||||||||
| Area | Size (mm2) | Area | Size (mm2) | ||||||||
| AB | 78 | ABH | 960 | AB | 75 | ABH | 945 | ||||
| BC | 86 | BCGH | 2700 | BC | 83 | BCGH | 2685 | ||||
| CD | 60 | CDFG | 2300 | CD | 57 | CDFG | 2285 | ||||
| DE | 38 | DEF | 160 | DE | 35 | DEF | 145 | ||||
| EF | 38 | EF | 35 | ||||||||
| FG | 64 | FG | 61 | ||||||||
| GH | 92 | SET 1 | GH | 89 | SET 5 | ||||||
| HA | 80 | HA | 77 | ||||||||
| CG | 36 | CG | 33 | ||||||||
| AB | 82 | ABH | 976 | AB | 72 | ABH | 930 | ||||
| BC | 90 | BCGH | 2716 | BC | 80 | BCGH | 2670 | ||||
| CD | 64 | CDFG | 2316 | CD | 54 | CDFG | 2270 | ||||
| DE | 42 | DEF | 176 | DE | 32 | DEF | 130 | ||||
| EF | 42 | EF | 32 | ||||||||
| FG | 68 | FG | 58 | ||||||||
| GH | 96 | GH | 86 | ||||||||
| HA | 84 | SET 2 | HA | 74 | SET 6 | ||||||
| CG | 40 | CG | 30 | ||||||||
| AB | 86 | ABH | 991 | AB | 68 | ABH | 918 | ||||
| BC | 94 | BCGH | 2731 | BC | 76 | BCGH | 2658 | ||||
| CD | 68 | CDFG | 2331 | CD | 50 | CDFG | 2258 | ||||
| DE | 46 | DEF | 191 | DE | 28 | DEF | 118 | ||||
| EF | 46 | EF | 28 | ||||||||
| FG | 72 | FG | 54 | ||||||||
| GH | 100 | SET 3 | GH | 82 | |||||||
| HA | 88 | HA | 70 | SET 7 | |||||||
| CG | 44 | CG | 26 | ||||||||
The grading system and assessment criteria are those as described in the module handbook in sections 11, 13 and 14.
Torsion of a racing car aerofoil