learning phase

1. Learning phase
(Final meeting)
CURT ‘22
Transmission system

2. ▪ Meeting Outlines
❖ Torque-power graph (Dyno-graph)
❖ How to reed catalogs data
❖ CAM drawings and files
❖ Why learning phase modifications !!!!!!!!!!??
❖ system modeling process
❖ How to design a decision matrix
❖ system mounting process
❖ Adding new material
❖ 2020 Transmission System analysis
❖ Members’ future responsibilities
❖ Introduction about simulation
❖ Pre-simulation steps
❖ Manufacturing plane
❖ Simulation steps

3. ▪ Why learning phase modifications !!!!!!??
1

4. ▪ Why learning phase modifications !!!!!!??
2

5. ▪ System modeling process
A simple car model was constructed to determine the gear ratio of the powertrain
as well as the max torque and speed that would be required for the motor.
Model inputs:
▪ car mass (m)
▪ tire radius (𝑅𝑊ℎ𝑒𝑒𝑙)
▪ tire coefficient of friction (𝜇)
▪ center of gravity height (ℎ𝑚)
▪ Wheelbase (L)
▪ weight bias or weight distribution (𝑙𝑚)

6. ▪ System modeling process
Step.1>> determining car max. acceleration.
▪ First: assume an acceleration a (in g's) and calculates the weight transfer to the rear wheels from this
acceleration using:
▪ Second: get the maximum theoretical acceleration (in g's) using:
▪ After determining this acceleration 𝑎𝑛𝑒𝑤,, it can be plugged back into the first equation and iterated
upon to converge to an actual maximum theoretical acceleration

7. ▪ System modeling process
Step.2>> The maximum velocity of the car during any competition event needs to be determined
▪ First: acceleration event (a 75m straight line drag race from a zero velocity start)
Using the kinematic formula:
▪ Second: Autocross or other events that have turns
It is possible that the car could reach higher speeds on the autocross course, so those conditions need
to be checked as well.
Although the full layout of the course isn't known until competition, certain parameters are, such as
the maximum length of straight after the smallest diameter corner and the largest diameter comer.
❑ Assume 𝑎𝑙𝑎𝑡𝑒𝑟𝑎𝑙= 1.5 g’s (from race car basics)

8. ▪ System modeling process
Step.3>> calculating the maximum wheel rpm
▪ From step.2 we get three different values for the velocity
o Acceleration max. velocity
o Small corner exit velocity
o Large corner exit velocity
▪ Compare between the three different velocities and get the maximum one to calculate
maximum wheel rpm using:

9. ▪ Car modeling process
Step.4>> calculating required torque
▪ First: calculate the force required to keep the car moving at a constant velocity due to rolling resistance of the
tires on the driving surface, which is defined as:
Where:
N ………..is the total normal force of the vehicle (car total weight).
𝐶𝑅𝑅………is the coefficient of rolling friction, 𝐶𝑅𝑅 ≅ 0.01 − 0.02.
▪ Second: Driveshaft torque (torque required per wheel) was calculated using:

10. ▪ System modeling process
Step.5>> preliminary selecting for the most suitable and available motor
❖ The most common electric motor brands:
❑ DHX
❑ Thingap
❑ Neugart
❑ Plettenberg
❑ Emrax
❑ AMK
❑ TG Drives
❑ Yasa
➢ What is the meaning or coordinates of
suitable and available !!!??🤔

11. ▪ System modeling process
Step.6>> determining the reduction speed (gear ratio) according to the selected motor specifications.
G.R=
𝑇𝑀𝑜𝑡𝑜𝑟
𝑇𝑊ℎ𝑒𝑒𝑙
incase of wheel drive
*assume no power losses😁🤷‍♀️
G.R=
𝑇𝑀𝑜𝑡𝑜𝑟
2∗𝑇𝑊ℎ𝑒𝑒𝑙
incase of rear drive

12. ▪ System modeling process
👀 Interview general task 👀
You are required to select a proper motor and calculate the reduction speed needed to satisfy the system requirements
according to the giving data:
Tire radius of 0.229m, with a coefficient of friction taken from the tire data sheet of 1.4. Wheelbase was set at 1 .524m.
Car total mass of 290kg with a rear weight bias Of 55% , and the center of gravity height is 0.279m.
Hint: For a hairpin turn of minimum diameter 9m, the maximum length straight is 60m. For a wide turn of maximum 45m
diameter, the maximum length of straight is 45m.
*Select the motor from Emrax motor catalog.

13. ▪ System mounting process
1𝑠𝑡
𝑖𝑡𝑒𝑟𝑎𝑡𝑖𝑜𝑛
3𝑟𝑑
𝑖𝑡𝑒𝑟𝑎𝑡𝑖𝑜𝑛
2𝑛𝑑
𝑖𝑡𝑒𝑟𝑎𝑡𝑖𝑜𝑛
4𝑡ℎ
𝑖𝑡𝑒𝑟𝑎𝑡𝑖𝑜𝑛
▪ Iterations for the different mounting methods of the system

14. ▪ Torque-power graph (Dyno-graph)

15. ▪ How to reed catalogs data????
▪ Data we can get from any product catalog:
➢ General information or product overview
➢ Technical data
➢ Product cad files or drawings
➢ Factory instructions
➢ Mounting methods

16. ▪ Decision matrix analysis
▪ Decision matrix parameters or criteria: (cost, compactness, simplicity, efficiency, performance,
manufacturability, assembling, maintenance,…..,etc.)
▪ Help us analyze a number of similar options to make a rational decision
▪ It’s useful when there is a number of options to consider but there is no obvious clear choice.
❖ There are two types of decision matrices:

17. ▪ CAM drawings and files
Manufacturing technique Required form
Traditional ( turning, milling, or drilling) Working drawing (pdf)
Non-traditional (CNC-Milling or Turning) Stl or step
Non-traditional (CNC-laser cutting, water jet, wire cutting, or router ) Dxf
3D-printing Stl or step
Sheet metal Dxf and working drawing (pdf)