Question

Small kids car with 300RPM motor and it goes 10MPH if the angle is 15°. The car can handle 150LB and the motor 50LB Total is 200LB.

1- What is the torque of the motor?

2- What is the stress analysis?

Hence:

Vout = 18 Volts

Vin = 12 Volts

Rated power : 250 W

Answer 1

Given :-

Rotational speed of a car, N = 300 rpm

V = 10 mph

Total load, F = 200 LB

P = 250 W

a)

taoque of the motor

P = (2pi*N*T) / 60

T = (P x 60) / (2pi x N)

T = (250 x 60) / (2pi x 300)

T = 7.96 N-m

b)

calculating diameter of the motor shaft of the motor

V = (pi*d*N) / 60

10 mph = 4.4704 m/s

4.4704 = (pi x d x 300) / 60

d = 0.2846 m

calculating the shear stress in the car

= 16T / pi*d^3

= (16 x 7.96) / (pi x 0.2846^3)

= 1758.65 N/m^3

stress due to direct load,

= F/A

= 200 LB / pi x (0.2846 / 2)^2

= (200 x 4.45 N) / pi x (0.2846 / 2)^2

= 13990.41 N/m^2