I have a rather trivial issue I am trying to solve, but it seems like there isn't anything available online that I can find to help me.
For this question, imagine I have a 2D annulus with a fixed inner ring and frictionless outer ring. I apply a moment to the outer ring and create...
I is the Inertia of the object in question i.e. Motor rotor. G is the shear modulus of the spring material, J is the polar moment of the spring - if it's a circular cross-section this would be (pi/32)*d^4, and L is the length of the spring.
There is a way you can measure MMoI of irregular geometry by attaching it to a spring (say a steel rod) about its centre and then measuring the period. From that you can find the Inertia using fundamental vibration analysis.
fN = 1/T = 1/(2*pi)* sqrt(k_theta/I)
Natural frequency or period, T...
Hi Chester, thanks for your reply.
Do you mean that the heat transfer area should only be the two faces that are perpendicular to the heat conduction in Figure a, i.e. what were used to derive the Tmax equation, and not the entire surface area of the box? I'm not sure I follow what you mean.
Its been assumed that the surfaces TL and TR of the same constant temperature.
Tmax = TL/R + (qdoto*L2)/(8*k)
q = ΔT/R
Rconvection = 1/hA
The Attempt at a Solution
The problem I am having with this question is conceptualising which dimensions to use...
I have a problem. I switched my major nearly two years ago within Engineering, however my university only has one course code for our entire degree which enlists all majors within it. So my issue is that they list ALL of my classes in my academic transcript and weight them all a whole...
I've been trying to debug a model I've created of a 4DOF geared system within Simulink by reproducing the results in MATLAB going from a 2DOF upwards to verify the dynamics are acting correctly.
At the moment I am purely trying to model the stiffness between two gears, my equations...
I've had the same experience before and what I can say is that don't dwell on this one test as it is one of MANY. Just keep your head up and work as hard as you have been prior to getting your result.
I'd most definitely request a consultation with your lecturer/tutor to go over said exam and...
Hi Randy, thanks so much for your input!
I have updated my stiffness matrix to include the stiffness of the bearings which is now:
And by solving the updated dynamic matrix, has yielded three purely positive eigenvalues with one zero.
So it seems like its responding as it should, now to see...
I am modelling a four degree of freedom system which is the dynamics of two spur gears in mesh, having two rotational and two translation degrees of freedom, respectively, a diagram exhibiting the system can be seen below.
I have derived the equations of motion (EOM) and...
I've derived a fourth order dynamic system as represented by the following:
I need to determine the eigenvalues for this system to check whether they're purely real with no imaginary components.
How should I go about doing this? I have done eigenvalue problems in the past, but not to...
Sorry, in the mainscript code that I listed I meant to take out the "k_mb = 50;". I have edited it and put it below.
% Mainscript for vibration analysis (19/01/2017).
%% Defining global variables
global r_p r_g I_p I_g m_p m_g k_mb
r_p = 10; % pinion...
I have the following ode code, and I want to know how I could output the variable "k_mb" within my main script so that I can plot it to see if it's actually active when the solver is integrating.
function zdot = odenesttest(t,z)
global r_p r_g I_p I_g m_p m_g V k_mb
Sorry, I'm still an intermediate at using the ode solvers with matlab. I'll list below what I have written (excluding what you have shown me previously).
% Mainscript for vibration analysis (16/01/2017).
%% Defining global variables
global k_mb r_p r_g I_p I_g m_p...
Just one more thing (I didn't think it'd be worthwhile beginning a new thread for this when you've responded in here). I'm now trying to incorporate the repeating function into my ODE solving function which obviously requires a bit of modification to the code we have in the previous posts. I'm...
This is great, works perfectly with the addition of this at the end:
if V(current_index) ~= max_angle
V(current_index) = ;
Otherwise the last entry in the V array is either over by 5 or 10. But with that, it works nicely.
I'll be sure to check out those...
Sorry for the confusion, let me explain. The purpose of this is to simulate the revolution of a pair of gears in mesh, so if the user wants to simulate 10 revolutions the angle will be 3600°, if they want to rotate the gears 1 revolution then the angle will be 360°, etc. So the angle is the only...
Once I start testing the ODE solver, I'll be sure to keep that in mind if it becomes an issue.
One further thing, see how the array, V = [0,5,15,20,30,35,45,50,60]; (pre-determined and put in). I want to write something that allows the user to input the angle and then the array is generated...
The addition of 'last' in the lower_index, fixed the problem instantly. Thus, for:
angle = 4 -> a_or_b_for_angle = 5
angle = 6 -> a_or_b_for_angle = 10
angle = 46 -> a_or_b_for_angle = 5
angle = 59 -> a_or_b_for_angle = 10
Thank you very much for your help, I'll use this as my base for my ODE...
Again, many thanks. I'm quite sure I know what it is trying to achieve.
If I run:
angle = 4;
V = [0,5,15,20,30,35,45,50,60];
A_or_B = [5,10];
lower_index = find(V < angle, 1);
even_or_odd = mod(lower_index,2);
a_or_b_for_angle = A_or_B(2 - even_or_odd);
The values of each vector are...
Maybe it'll be more clear if I explain the application. I am trying to make a function that allows me to apply a torsional stiffness for gear teeth in mesh, as the gear rotates the gear (in this case) will be in either singular contact or double contact. Where I'm assigning 5° for single and 10°...
Do you mean for each interval there would be an if statement associated with it? This is the nature of the application that I require for an example of 60°:
See how the function needs to be able to periodically apply the values dependent on the total angle...
I need your help writing the meat of a function that I need for a MATLAB script I'm writing.
The jist of it is, starting from 0°, when between 0.0° - 5.0° apply a certain value, when between 5.0° - 15.0° apply another value. However, the relative amount of rotation can be user...
I've started to do research for my undergraduate thesis topic and I would like to use FEA with an application to quantum computers. I'm thinking of something in regards to mechanical vibrations, however I'm open to consider anything given it's possible at the undergraduate level...
Interesting thought, I'd be inclined to think that if we did have the ability to alter earths rotation by means of rocket propulsion than the emissions from said rockets would impact the climate indirectly.