Static beams for dummies anyone spare a moment ?
Static beams for dummies anyone spare a moment ?
(OP)
Hi all I currently have one week to prepare for a job interview as an engineering teacher . I need to prepare a 2 hour lesson for 16 year olds who know nothing about static beams ... I myself am a little out of practice on this area but obviously have some knowledge ... Anyone able to help me out with tips and what direction to take :)





RE: Static beams for dummies anyone spare a moment ?
Most of the class will be bored unless, and probably even if, you frame the lesson as predicting the deformation of a homemade bridge over a swamp full of alligators or some such.
Mike Halloran
Pembroke Pines, FL, USA
RE: Static beams for dummies anyone spare a moment ?
RE: Static beams for dummies anyone spare a moment ?
i'd do a photoelastic problem ... plastic beam + sunglasses + load = stress
and you could show them some real pictures of Kt geometries.
possibly showing them the difference between simply supported and cantilever beams ?
Quando Omni Flunkus Moritati
RE: Static beams for dummies anyone spare a moment ?
mind you the response will probably be "sooooo"
Quando Omni Flunkus Moritati
RE: Static beams for dummies anyone spare a moment ?
Mike McCann, PE, SE (WA)
RE: Static beams for dummies anyone spare a moment ?
Regards,
Mike
RE: Static beams for dummies anyone spare a moment ?
Then the different bridges get tested to see which takes teh most load.
2hr may be pushing it but you never know.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Static beams for dummies anyone spare a moment ?
RE: Static beams for dummies anyone spare a moment ?
RE: Static beams for dummies anyone spare a moment ?
Have them span a certain distance, and whichever bridge holds the most load before failure wins.
RE: Static beams for dummies anyone spare a moment ?
Just sayin...
RE: Static beams for dummies anyone spare a moment ?
RE: Static beams for dummies anyone spare a moment ?
How about a 12" rule balance on two books and apply a load by hand in the middle of the rule for starters.
RE: Static beams for dummies anyone spare a moment ?
If they will all have (or hand out) rulers and books, asking them to experiment is a neat idea.
Have they had any calculus, do they know simple integrations?
Use the Torrance incubation model to plan the lesson outline, look it up, or contact me, I can dig up a reference moon161@gmail.com
Show simple beam in various configurations, ask what things that idea might model. Pose your questions to class using their choices for what the beam is, what the loads are, etc.
Look up khan academy topics, for both content and style. If possible assign 1 or 2 khan academy lessons as homework before the lesson, but don't count on it being done.
Plan appropriate participation activities. I would say put the questions out there at the beginning, 'does it bend, how do you know, is it linear, quadratic, etc. Don't shoot down the answers, just use them as a starting point for discussion.
Get more questions out there, what to the forces look like in beam, reactions equilibrium, introduce shear and moment forces, touch on moment of inertia.
Develop equilibrium, shear, moment diagrams, check in frequently, every 5 minutes or so. Consider developing 1 point cases and using superposition.
Walk through a few examples, wrap up with them solving the same simple case you presented at the beginning of class, say last 15-20 minutes. Plan on checking in, coaching and troubleshooting method with various students.
RE: Static beams for dummies anyone spare a moment ?
That's my opinion anyway.
Regardless, I think there are two critical things you need to cover. First, the math, for which you will need to be interesting and they will need to be interested (hence relating it to hobbies and interests of theirs) and second, the concept, the chief of which being that the second moment of area scales with cube of distance from centerline. If they already have learned about torque then that concept will be easier, but I think it's a good place for a demonstration.
To show them it happening, obviously you can just get a popstick and have them try to bend it in different ways, to show them WHY it happens is a bit harder - perhaps a cantilever beam 50-60mm tall made of rubber with some markings every 10mm up the side of it. They can bend it and literally see the strains - then it's up to you to relate how the ones on the top and bottom deforming so much more than the ones in the middle means that they are contributing more to the stiffness, and relate it to torques if they understand them, and that those ones on top and bottom also have more mechanical advantage.
And you have to do all that all without them getting bored.
Good luck!
RE: Static beams for dummies anyone spare a moment ?
C-clamp a small square beam (1/2 x 1/2 bar0 to the science desk, load it up until it bends.
Change to a 1/2 x 2 beam, same length. bend it.
Change to a angle iron or small channel, so how they twist under load.
Show how the channel resists one way, but fail in the other.
Change to a small WF shape, show how it is lighter, cheaper, but resists both ways.
Clamp the beam vertical, wiggle it to show "same problem", and then introduce compression forces. Don't go into a lot of discussion - you're working beams.
RE: Static beams for dummies anyone spare a moment ?
Alternatively, and especially in the available time frame, demonstrations may be better.
I'd say you need to grab their attention first, maybe with some initial demo, then maybe explain some of the principles behind it, and then maybe do more demo's to illustrate what you've just taught them.
Is this just a general class, or is it kids that have already volunteered for this because they have a specific interest in Engineering? If the latter you'll have more scope to get into math and explanations without needing to worry as much about keeping their attention.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Static beams for dummies anyone spare a moment ?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Static beams for dummies anyone spare a moment ?
Show it (beam deflection under loads, beam failure under loads, beam reaction (the beam bends but is safe one direction, fails the other direction). Beam fails if wood, beam bends if steel, beam cracks if brittle (plastic). Be exciting! Break a few wooden 12 inch rulers! Bend a few thin strips of cheap steel. Buy a 3 foot channel from Home Depot and a couple of angle iron from Lowes to let them "feel" a real steel shape. Crack a plastic "beam" to show that deflection is NOT always constant.
Only then, at the end, simply write the final equations for allowable stress, load amount, load position, beam shape values, beam thickness, beam depth as your conclusion. Not as the start of the example in oyour class.
Show which is "on top" of the formula, which is "on the bottom" of the fraction, which factors are going to make stress rise if they increase, which will make stress fall.
You are NOT going to "teach" a course here in beam theory, you are trying to excite them visually so they might (much later) remain excited about theoretical courses about beams.
RE: Static beams for dummies anyone spare a moment ?
RE: Static beams for dummies anyone spare a moment ?
maybe review JE Gordon's book "why things don't fall down".
Quando Omni Flunkus Moritati
RE: Static beams for dummies anyone spare a moment ?
This link might help
http://www.teachengineering.org/view_lesson.php?ur...
RE: Static beams for dummies anyone spare a moment ?
RE: Static beams for dummies anyone spare a moment ?
RE: Static beams for dummies anyone spare a moment ?
RE: Static beams for dummies anyone spare a moment ?
RE: Static beams for dummies anyone spare a moment ?