Trojans take on engineering

[Grimm Reaper Racing]

As someone who has had 4.5 years of mechanical engineering classes, the salary and job title of engineer, it's now my turn to throw in a couple of cents worth.

Break down of engineers:

75% Crappy engineers - Lack real world experience.  They get stuck in manufacturing engineering positions, or in crappy economies like the present, are likely laid off for long periods of time.  I call these engineers problem makers instead of problem solvers.

20% Okay engineers - good with calculators, always hear them saying things like "Well it looks good on the computer screen" or "It works on the computer"

4% Great engineers - These are the true problem solvers of the engineering world. They have lots of real world experience.  These people usually have many patents and they tell the okay engineers and the crappy engineers what to do.  These are the guys who use there brains instead of their computers.  These guys will never be out of a job for long periods of time.

0.75% Professional engineers - These guys are insured and bonded. They put their life and livelihood on the line every time they put their wet stamp on an engineering drawing. (These guys are also known as Crazy engineers)

0.25% Smart engineers - These engineers really are brilliant.  They take some great engineers concept and modify it just enough as to not get into copy right infringement lawsuits and make millions.


 

[sanddan52]

New guy here. First some background information.

I have been an engineer for 20 years and got my PE license 15 years ago. I designed underground mining equiptment for 13 years, primarly front end loaders. We did many calculations, FEA and strain gage testing. Here's my take for what it's worth.

Designing a part is the process of deveeloping a concept and taking it through to final drawings. In my case this is all done on a computer using Solidworks.

Engineering is the analysis part of the process. This can be calculations, FEA or testing. You can be a designer without the education but not an engineer. The product I currently work on is pure design, no engineering required.

If you took a existing a-arm and reconfigured it in some way, (hopefully improving it), that would be "redesigned". If you modeled the original design in cad and then did some stress analysis to help determine the weak points and then came up with an improved desgn, that's "engineered".

Just because it's engineered doesn't mean it won't still break under some load condition. The art in the engineering is determining the load inputs when working with such a complicated system as an off road vehicle. That's where experience and testing come in.

[chuckorlando]

I think it's the diff between design and engineer. People were doing design work long before math. Someone designed the spear. Then redesigned over and over. Then someone got smart and enginered one. The engenered ones are found in the olympics. The designed ones are leaned against a hut door somewhere waiting on the hunting party. In my openion if you got some sence and are a thinker you can design things all day. That design may take years to work right. Thats where the enginering comes into play.

[standfast]

It is pretty naive to think that you need to FEA a buggy for it to be called designing.  It's very naive to think that you
can replicate all the conditions that an off road car will experience.  IMO, if you can't design a simple space frame 
without FEA and only using all the info that is already available on this subject that is out there than you are not that
good of a engineer in the first place or you are seriously lacking in hands on experience.   The design aspect in our cars
comes into play with the suspension for the most part.  Making it perform and handle exactly as desired and
understanding how you want it to perform.   Not in running FEA on stuff which inevitably you will be using estimated
values for.  NO ONE person or manufacturer will ever FEA an entire car to the point of it not needing testing.  If
running FEA on a couple load paths with some BS numbers that you guessed on helps you justify an engineering degree,
than more power to ya I suppose. 

I'll take real world testing anyday of the week in THIS application. 

[fabr]

It's still all based on a WAG ultimately. The WAG(wild ass guess) is what everything comes from. IMO,not worth much I know, FEA and all the other stuff can be used most effectively by showing that something CANNOT do whatever more so than showing that it WILL do anything. Am I wrong and how so if I am?

[LiveWire]

The Wright brother's built a small wind tunnel to test models of wing and propeller designs. I believe modern aircraft propellers have an efficiency level only 5% better than theirs. It was primarily trial and error. I would consider them engineers though which I'll get into later. They would have started with WAG. The first propeller was probably slanted boards. Their drag testing on wings revealed that the the air foil shape caused less drag. They applied experience from one thing to another and made the prop air foil shaped as well. Still trial and error though. In determining which angle of attack provided the best thrust for the power input, I would guess that they did not just keep tweaking it 1 degree at a time and tested every possible permutation of length, angle, etc. I would imagine they went about it in a methodical approach such as a 10 degree change until they pasted the optimal point then either did made or made an educated guess as to a good starting point halfway between the previous two best points. Making calculations to determine the next step based on previous real world results is where I would call them engineers. Next they probably kept a table of optimal prop angle for various RPMs. Since the outer end of the prop has a higher speed than the inside, they made the inside of the prop have a steeper angle than the outside. There is no way they simply fell into the rate of increase of angle. They had to have determined optimal angle for a given speed then calculated the angle over the length of the blade.

Using computer software to model how a part performs is still trial and error. An educated guess was made at what is needed. It does not matter if tensile strengths were looked up, etc. That just adds to the educated part of the educated guess. If it were possible to build a part solely off calculations then there would be no need even for modeling how a part performs. You would know the results before the models were even run. If the part fails in the model, the weak points get beefed up and the model run again. It is just to save time over building a prototype for destructive testing. Either way, someone could simply build it beefier and try again. They could also measure what it took to break then calculate how much thicker the material needs to be to prevent the failure. I think it is more about the methodology and thought process than the tools used. Either test may still not represent how it is stressed in real use.

[chrishallett83]

Propellors? A genuinely fascinating subject: http://en.wikipedia.org/wiki/Propeller for starters...

[trojan]

Fab, I'm honestly trying to rationalise where you're coming from, do you equate WAG with estimate?

[fabr]

yup

[trojan]

OK

I'm not going to pick about defintions of words....
I get you now, see I do try

[fabr]

That's fine. I TRY to understand Strine! To me an estimate is a WAG. A good one perhaps but still a WAG.

[trojan]

That's fine. I TRY to understand Strine!

Ok now let's move on to politics

[fabr]

Only this time we'll bash on all Oz has wrong with it instead.

[chrishallett83]

Whats wrong with Australia?

Other than that wanker Trojan living here, I mean!

 

[Yummi]

Toilets flush backwards.