Week 9-10/17/2018

For this week, the team is preparing for presentation next week.

Articulation of bogies:

• Completed design for new, light weight Z-bracket in Solidworks.
• Performed FEA on the Z-bracket
• FEA results show a need for thickness in material, Safety factor below 1.
• Working on changes to design.
• Plan on 3D printing rapid Prototype
• NEED to add a rib on steering rack reduce moment arm caused by the bearing holder
• Possibly make plates 5mm thickness instead of 3mm

Spring Loaded Guide Arm:

• Performed Calculations for Max load of spring and spring rate
• Researched for the damper criteria for selection
• Calculated frequency for damper and Max energy absorbed
• The natural frequency of the system is much lower than the frequency of force given by the track, so this means that resonance will not occur.
• Dr. Furman concludes,from the results, that a damper is not practical and cost effective for Maker's Faire. However, I will included into design, but not actually included in real application.
• There will not be any changes to the width between the track, so I am redesign the whole design around a smaller wheel diameter to accommodate 12 cm gap. Also, I am redesign using the initial FEA result I got from the first model, and am changing the slot design.
• The plan is to 3D print the spring loaded component.

ME 195a Spring loaded guide Arm calculations

Akash Sandhu

Contents

• Force calculations
• Spring Calculations
• Damper (Shock Absorber) Calculations

Force calculations

M = 500:100:7000; % kg, weight of whole bogie and loaded podcar
total_length = length(M)-1;
% v_min = 2;
% v_max = 20;
% dt_v = (v_max-v_min)/total_length;
%
% v = v_min:dt_v:v_max  % m/s, operating speed of bogie
v = 1 % m/s
r_min = 8;
r_max = 50;
dt_r = (r_max-r_min)/total_length;
r = r_min:dt_r:r_max;   % m,   smallest radius

for i = 1:length(M)
    for j = 1:length(r)
        f(i,j) = 2*((M(i)*v^2)/r(j));
    end
end
figure(1);
surf(M,r,f);
xlabel('Mass [kg]');
ylabel('Radius [m]');
zlabel('Force [N]');
title('Force vs Curvature and Mass');

v =

     1

Spring Calculations

clear all; clc;
M_tot = 2000 +300; %[kg]
M_eq = M_tot/3;
x = .13; % [m]
v = 1; % [m/s] about 2 mph
r = 8; %[m] radius of curve
F = 2*((M_eq*v^2)/r); % [N]
fprintf('The force acting on each spring is %1.3f N\n ',F)
k = F/x; %[N/m]
fprintf('The Spring rate is %1.3f N/m \n',k)

The force acting on each spring is 191.667 N
 The Spring rate is 1474.359 N/m 

Damper (Shock Absorber) Calculations

F = 2*((M_eq*v^2)/r); % [N]
M_tot = 2000 + 300; %[kg] pod + bogie
M_eq = M_tot/3; % [kg]
v_y = 13; % [m/s] speed going straight
L = 0.016;% [m] stroke of damper
theta_deg = 13; % [degree] angle of curvature
theta = theta_deg*(pi/180); % [rad]
v_x = tan(theta)*v_y; %[m/s] speed at impact
FS = 2; % factor of safety
E_1 = 0.5*M_eq*v_x^2;
E_2 = F*L;
E_tot = E_1+E_2;
E_max = FS*E_tot; %[Nm] max energy absorbed
fprintf('The max energy the damper needs to absorb is %1.3f Nm\n',E_max);

wavelength = 0.05; %[m] irregularities observed at
freq = v_y/wavelength; % [Hz]
fprintf('The forcing frequency from the track irregularities will be %1.3f Hz\n', freq);
freq = freq*60; % [ cycles/min]
fprintf('The damper will need to be able to do %1.3f cycles/min\n',freq);

The max energy the damper needs to absorb is 6912.052 Nm
The forcing frequency from the track irregularities will be 260.000 Hz
The damper will need to be able to do 15600.000 cycles/min

Published with MATLAB® R2018a

Brakes

• The brake pads are selected
• The spring and electromagnet is also selected
• Designing mounting method for the system under the rail; also there is new conflicted to deal. Now, the space needs to be shared with 6 linear motors.
• CAD model for the braking system is being produced