Recent content by Sirsh

  1. Sirsh

    Programs Is Chemistry a useful minor for a MechEng Major?

    Material science would be a most useful minor than chemistry, in my opinion.
  2. Sirsh

    Having trouble with a heat sink in ANSYS NLT

    As Mech_Engineer has said, if you can provide more information we will be more able to help you.
  3. Sirsh

    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.
  4. Sirsh

    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...
  5. Sirsh

    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.
  6. Sirsh

    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...
  7. Sirsh

    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...
  8. Sirsh

    Testing Struggling with Statics: Any Tips for Improvement?

    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...
  9. Sirsh

    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...
  10. Sirsh

    I Finding eigenvalues for 4 DOF system

    Thank you for your help Jambaugh!
  11. Sirsh

    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...
  12. Sirsh

    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...
  13. Sirsh

    MATLAB How to Output k_mb for Plotting in 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...
  14. Sirsh

    MATLAB How to Output k_mb for Plotting in ODE45?

    Hi all, 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. odescript function zdot = odenesttest(t,z) global r_p r_g I_p I_g m_p m_g V k_mb A_or_B =...
  15. Sirsh

    MATLAB Efficient MATLAB Repeating Function for User-Defined Rotations

    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). Main script: % Mainscript for vibration analysis (16/01/2017). clear all; clc; %% Defining global variables global k_mb r_p r_g I_p I_g m_p...
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