Engineering as a tool or a product

[looksatstars]

I am curious to other engineers thoughts on a question nagging me:

Is an engineer's job to find the safest option to construct or repairing OR is it the engineer's job to find the most economical, reliable way of doing the work safely.

Explanation:
I heard the quip- "Anyone can build a house but an engineer can build a house so it just stands"
And personally I feel that is the engineer's job. To work within the regulated guidelines and not to overconstruct but to find economical ways of building without compromising safety.

I see in alot of posts the words, use a factor of X and that will suffice for any conditions, which in effect is applying a safety factor to "cover up" any overlooked details.

I am all for safety but I think the threat of lawsuits and the enormous workloads have been pulling us away from the true meaning of engineering.

 

[MintJulep]

Q: What is the safest way to cross the street?

A: Don't cross it.

 

[Ron]

You raise an interesting question; however, as engineers we have an obligation to protect the health, safety, and welfare of the public. We are bound to this both ethically and legally as licensed engineers. That premise sometimes gets in the way of "the most economical" solution for a client, simply because not all variables can be accounted, so often there is a necessity to apply "a factor" so as to mitigate a potential for failure when designing to such a limit state as you've described.

Make no mistake about it. The litigious climate has changed many engineering decisions, because engineers must ascribe to their standard of care, which is usually not a minimum nor a maximum, but somewhere in between.

 

[IRstuff]

It's not a question of "covering up" overlooked details. It is simply a fact of life that you cannot simulate nor analyze every detail and facet of a problem. If you did, you'd could, as I've done, spend months analyzing a single circuit or joint or what have you. Additionally, even the best FEA is limited by the amount of detail that you can input in a plausible amount of time and the ability of the computer to run the analysis in a plausible amount of time.

Every analysis problem is an abstraction, i.e., a simplification of the real problem. Therefore, you don't "overlook" details, you simply ignore them to get the problem solved in a reasonable amount of time. This forces you to allow for such ignored details to perturb the solution.

Additionally, not everything you can buy is actually built to specification. Many years ago, and even today, there are counterfeit bolts and other hardware that are substandard. Part of the safety factor goes into accounting for parts and components that are operating below specification.

Finally, the reality of any design problem is that the customer has finite money and time. This limits how much design and analysis you can possibly perform. Every year, however, does bring better computers and, hopefully, faster software, but all that is coupled with more complex designs. The end result is a standoff between what you can ultimately design for safety and what you can practically design for safety.


Every licensed engineer can probably design a structure for California that can withstand a magnitude 9 earthquake. However, it would be too expensive, too ugly, too short, and too untimely for any customer interested in getting a building built to house his business. Therefore, every design is a compromise of time, money, and safety.

TTFN

 

[sms]

The old saying is that you can have it cheap, fast, or good (high quality) pick any two. Cheap and fast wont be good, fast and good wont be cheap, good and cheap wont be fast.

Engineering is about striking the right balance. I agree with IRstuff, I would add that in every engineering problem we make assumptions particularly in regard to boundry conditions. Those assumptions are rarely 100% right, a little safety factor is generally wise.

-The future's so bright I gotta wear shades!

 

[KENAT]

Also a reason things are designed with larger margins is to include the capacity for 'growth' and to a limited extent allow for the way it might be used, even though it isn't designed to be used that way.

I would have thought the biggest problem though (as stated above) is that we never really know exactly what the true boundary conditions/loads etc are, we make our best estimate and then apply a factor for things not just that we've ignored, overlooked or forgotten but also for things we have no way of knowing about.

For me Safety should always be the primary concern, doesn't mean it has to be 100% safe (usually impossible), for reasons given by others and more but that Safety should always be considered and anything that may reduce safety carefully considered.

 

[Ashereng]

Engineers work in reality. The reality is, there are always competing pressures. Get it done, quick, cheap and well.

An engineer's job is to meet the minimum level of all the competing requirements, without sacraficing.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[HVACctrl]

There are many factors:

1) You can overdesign because precise, detailed engineering might cost more that the project is worth- particularly on a one-time, small project.
2) You can go into great detail and design with great intricacy on something that might be reproduced numerous times. In this case, the savings in material and construction costs will make up for the more expensive engineering.
3)...

The point is that it all depends on the scenario. I might be able to sink a whole year designing coming up with the nicest paper airplane to ever exist, but who's gonna pay my salary for that?

Ed

 

[Ashereng]

HVACctrl,

Have you tried Mattel? ;-)

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[IRstuff]

We, two engineers, just tried to put together one of those "fold and fly" paper airplanes and were completely stumped by the instructions.

Moral: Get someone to engineer the assembly instructions, while you're at it.

TTFN

 

[waskillywabbit]

Simple...

To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, it is twice as big as it needs to be.



Brian

 

[KENAT]

I just re-read the original post again.

Is an engineer's job to find the safest option to construct or repairing OR is it the engineer's job to find the most economical, reliable way of doing the work safely.

Depends on what the customer asks for.

If the customer asks for the safest widget that's what we give him.

If the customer asks for economical/reliable widget we give him that with (unless otherwise stated) what we consider acceptable safety.

This is why the requirement is so important, as my Design Prof taught!

 

[wes616]

this thread reminds me of the joke...

A mathematician, a physicist, and an engineer were asked to review this mathematical problem. In a high school gym, all the girls in the class were lined up against one wall, and all the boys against the opposite wall. Then, every ten seconds, they walked toward each other until they were half the previous distance apart. The mathematician, physicist, and engineer were asked, " When will the girls and boys meet?"
The mathematician said, " Never."
The physicist said, " In an infinite amount of time."
The engineer said, " Well... in about two minutes, they'll be close enough for all practical purposes."


Wes C.
------------------------------
When they broke open molecules, they found they were only stuffed with atoms. But when they broke open atoms, they found them stuffed with explosions...

 

[debodine]

One of my favorite jokes that includes an engineer (but not as the butt of the joke):

A doctor, an engineer and a lawyer were discussing whose profession had been around longest of the three. Appealing to the creation story in the book of Genesis in the Bible, the doctor claimed, "God created Eve from one of Adam's ribs, which is surgery. Therefore my profession predates all others."

The engineer said, "Go back even further to the first chapter and it says that from the chaos God created the heavens and the earth. That is a massive feat of engineering, therefore engineering predates medicine."

Both the doctor and the engineer turn to the lawyer and challenge, "Top that!". After pausing for dramatic effect (as is the wont of lawyers), the lawyer states, "Who do you think created the chaos?"

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