What do we do to fill the Physics Gaps

Pedagogical ideas with no mathematics!! (Basic physics)

Simulation gives you everything.

  • Idealise do geometric and material modeling.
  • Know your operating conditions.
  • Simulate and interpret results.
  • Play around with material options
  • Play around with support conditions.
  • Know your design space and optimize geometry.


Derivable pleasure decreases as the entropy (tidiness of the room increases) against derivable mechanical energy run downhill as the entropy of the system increases.  

Converting fresher to a designer

Step 1 Make the facts native
Step 2 Use algebraic physics to explain equations
Step 3 Build clarity on problem definition
Step 4 Build feel for numbers
Step 5 Advanced design facts
Step 6 Kindle the imagination on specific product situation to achieve the solution

Pedagogical idea 1: MAKE THE FACTS NATIVE

List all the concepts and give clarity in layman’s language.

Example 1

Sophistication: Young’s modulus reduces with temperature hence stiffness reduces (axial, bending, shear, torsional) as for isotropic materials.

Native expression: When you heat the metal, it is easy to stretch, bend and twist hence temperature reduces stiffness or increases flexibility.

Example 2

Sophistication: Stiffer system has higher natural frequency

Native expression: Stiffer component hurries back to original position so takes less time to oscillate to and fro.

Example 3

Sophistication: Bearing support structure reduces the stiffness of shaft system if the bearing support structure is not rigid.

Native expression: If you support the shaft on hard supports, shaft deflects less but if supported on flexible supports it deflects more.

Example 4

Sophistication: Gyroscopic effect provides damping unlike physical does not dissipate energy.

Native expression: If no air resistance and no friction in the bearing a fan spins perpetually. Hence any work supplied to overcome the inertia does not dissipate rather is stored as kinetic energy in the fan.

Note: Gyroscopic effect leads to whirling disc consuming of extra energy, thus stiffening the component.

Also, do build facts for inertia.

Pedagogical step 2: Algebraic physics (Exploit previously visualised facts)

“Unobvious facts for a cantilevered shafts with heavy discs cannot wobble but only move up and down. Hence stiffness increases 4 times”.

Pedagogical step 3: Build clarity on problem definition

  • Why I need a vibration margin?
  • If I do modal analysis, I get a large number of frequencies. Which should I be interested in?
  • What is the gap between the first fundamental frequency and the worst operating speed?
  • Should I consider speed and frequency coincidence only when it sustains for a significant period (dwelling resonance and not passing resonance)?
  • Why do not we compute axial frequencies generally?
  • Why margin is generally established against flexural natural frequency and why not torsional?

Let candidates visualize various modes! Via simulation and hence appreciate effective inertia. 

Pedagogical step 4: Build feel for numbers.

  • What material typically shaft is made from and what are the mechanical properties?
  • Is the mass of the shaft significant compared to elements supported by it?
  • How much young’s modulus reduces with temperature?
  • What are the temperatures for various product lines?
  • Typical shapes of bearing support structures and stiffness numbers
  • List goes on!

Pedagogical step 5: Advanced design facts

  • Now introduce Campbell diagram.
  • Explain how to construct and how to read?
  • Spend explaining all possible excitation agencies use powerful animations and native narration keeping it almost non-technical.
  • The excitation lines will then have the following order numbers: motor 1X, 2X, variable frequency drive 6X, 12X, 18X, etc., for a motor with two poles with a variable frequency six pulse VSI (voltage source inverters) drive.
  • Torsional frequency not influenced by speed only flexural frequencies.
  • List goes on!

Pedagogical step 6: Kindle the imagination on specific product situation to achieve the solution.

Give a typical sketch of shaft bearing support structure system and start asking questions.

  • What happens if we redesign the shaft?
  • Could we vary cross sectional thickness does manufacture support it?
  • What happens if we redesign bearing support structure?
  • Could we replace the material? How it impacts design and benefits

Instructor must be a facilitator and Google must be extensively used by students while suggesting various design changes!!

Instructor must finally share design best practices and memory map with candidates!

The story continues but this episode ends!!


Preparing thinkers for tomorrow!

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