Nerd's Lab For Engine Vibration
Backstory:
Being an engineer, I love math but I believe that MATLAB has added more fun and enthusiasm when it comes to the applicability of math in real life engineering scenarios.
Opportunity:
Being an M.Tech student from Vellore Institute of Technology (VIT), I was provided with an opportunity to do 9 months internship programme at Engineering Research Center (ERC), Tata Motors Ltd., Pune. This programme is also a part of my final year project in order to complete my master degree.
Overview:
I was asked to study NVH aspects of passenger cars, drivelines specifically. While doing literature survey and in-house field study about the vehicles, I sensed an opportunity to enhance the driveline performance by targeting torsional vibrations. I selected Engine as the main part of study.
At the end of 4 months of work I have developed a Matlab App using Matlab Graphical User Interface Development Environment (GUIDE) to simulate the torsional domain of Engine vibrations completely.
Login page
Cool features: Pop-up message boxes, to guide the user at each action.
Welcome page
Basic info about the mathematical model used for simulating torsional vibrations
Cool features: User defined edit boxes with the reference image provided which shows the parameters representing the each and every engine component in mathematical model
Clicking on 'Display Frequencies' will display first 6 natural frequencies of torsional modes. User can skip to next step without calculation of frequencies by pressing 'NEXT' .
Cool features: User defined edit boxes. Each and every edit box in this app comes loaded with pre-defined values based on literature & experiments.
Loading pressure data page, which shows the example image of arranging the data in suitable format for further use.
Cool features: By clicking on 'Load File', user will be facilitated with file selector to select the file from anywhere on the system. Once file is loaded, the path is shown to avoid mistakes by user. Hence, data file need not to be in same directory.
Run the model as per type of results required
Cool features: When user select's Run for Torque, a live process bar will appear showing the progress of calculations. If any actions taken by user in-between calculations then a suitable message box is prompted. Otherwise user will be directed to result visualization page.
Cool features: Result visualization process is made as easy as possible. Also results can be saved as figure files, or as in workspace of MATLAB. Figure window shown here, facilitates the user in many possible ways such as zoom in, zoom out, rotate, get values at particular point, etc.
Run the model as per type of results required
Cool features: When user selects 'Run', a live process bar will appear showing the progress of calculations. If any actions taken by user in-between calculations then a suitable message box is prompted. Otherwise user will be directed to result visualization page.
Cool features: Result visualization process is made as easy as possible. Also results can be saved as figure files, or as in workspace of MATLAB. Figure window used here, facilitates the user in many possible ways such as zoom in, zoom out, rotate, get values at particular point, etc.
Behind the scenes:
Though App is made as much as user friendly but there are certain computational time limitations because of large number of calculations being involved at the back ground.
This app has almost 1000 lines of purely Hand-written computations and about 200 lines of auto generated codes for automation of GUI and user inputs.
On top of matlab script files, this app is also running a giant simulink model for solving dynamically coupled differential equations. The masked model is shown in the figure below.
Simulink model for Engine Torsional Vibration equations
Validation of results:
As of now the simulation results are showing good co-relation with experimental results. Due to limitation of data sharing I may not be able to show all the plots of validation but a torque validation plot is shown below.
Usefulness of App:
This app can only be useful for simulating in-line 4 Cylinder IC engines as of now. Also the result visualization window consist of time domain study only, but one can save the result plots as a vector and can obtain frequency domain study using inbuilt signal processing tool of matlab.
With the help of this app user can study the available engine configuration or user can optimize the torsional vibration dampers with respect to inertia, stiffness and damping values for minimizing the driveline torsional vibrations.
Thank you for your valuable time..!!
