# Recent content by Sirsh

1. ### Programs Is Chemistry a useful minor for a MechEng Major?

Material science would be a most useful minor than chemistry, in my opinion.
2. ### Measuring relative rotation of node - ANSYS WorkBench

Hi all, 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...

4. ### How to measure the moment of inertia of a motor's rotor?

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.
5. ### How to measure the moment of inertia of a motor's rotor?

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...
6. ### Heat Transfer - Conduction/Convection Question - Which area?

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.
7. ### Heat Transfer - Conduction/Convection Question - Which area?

Homework Statement Its been assumed that the surfaces TL and TR of the same constant temperature. Homework Equations 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...
8. ### Other How/where to explain grade discrepancy in job applications?

Hi all, 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...
9. ### MATLAB Issues Replicating Simulink Model within MATLAB (2DOF)

Hey all, 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...
10. ### Testing Failure on statics exam?

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...
11. ### 4DOF Spur Gear System - Eigenvalues not corresponding with the Eqns?

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...
12. ### I Finding eigenvalues for 4 DOF system

Thank you for your help Jambaugh!
13. ### 4DOF Spur Gear System - Eigenvalues not corresponding with the Eqns?

Hi there, 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...
14. ### I Finding eigenvalues for 4 DOF system

Hey all, 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...
15. ### MATLAB Passing variables out of ODE45

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. Updated mainscript % Mainscript for vibration analysis (19/01/2017). clear all; clc; %% Defining global variables global r_p r_g I_p I_g m_p m_g k_mb r_p = 10; % pinion...