Vehicle Ride 2

The objective of this assignment is to understand the damper characteristics by calculating its parameters and plotting a force vs velocity shock curve from the calculated information.

Manual calculations in excel:-

• Ride calculations:

1. Wheel rate(Kw) = Ks*(MR^2).
2. Ride rate(Kr) = (Kw*Kt)/(Kw+Kt).

• Damper calculations:

1. Sprung mass critical damping(C_crits) = 2*sqrt(Kr*ms).
2. Unsprung mass critical damping(C_critus) = 2*sqrt((Kt+Kw)).

1. Sprung mass initial damping co-efficient(C_s) = damping ratio*C_crits.
2. Unsprung mass inital damping co-efficient(C_us) = damping ratio*C_critus.

1. Low-speed compression damping co-efficient(C_cls) = C_s/2.
2. High-speed compression damping co-efficient(C_chs) = C_us/2.

1. Low-speed rebound damping co-efficient(C_rls) = C_cls*rebound_ratio.
2. High-speed rebound damping co-efficient(C_rhs) = C_chs*rebound_ratio.

The algorithm

A Matlab algorithm was developed to calculate the compression and rebound forces for the given range of damper velocity, which was then used to plot the Force v/s Velocity curve for the dampers.

The algorithm consists of three parts:

• Declaring input parameters:- In this part, all the input required input parameters were declared as per the previous calculations in the excel sheet.

• Initialization and main loop:- In this part, the code was initialized using for loop and if statements. The if statement was used inside the for loop to distinguish between the velocity before knee speed and after knee speed. The corresponding forces were calculated using the formulae as shown below:

           Below knee speed

           Compression_force(F_c) = C_cls*vel_d;

           Rebound_force(F_r) = -C_rls*vel_d;

           Above knee speed

           Compression_force(F_c) = F_c(n-1) + ((vel_d(n) - vel_d(n-1))*C_chs;

           Rebound_force(F_r) = -F_r(n-1) + ((vel_d(n) - vel_d(n-1))*C_rhs;

The negative sign was used in rebound force calculation in order to plot the rebound profile in the 4th quadrant for better visualization and understanding. 

• Plotting the results:- The above loop was solved and results were plotted for the Force v/s velocity curve for the given damper. The entire code with plots is attached in the link below:

https://drive.google.com/drive/folders/1uLTvrnL3IsjG1DyASIDugLfxNxN9-v8D?usp=sharing