You have probably heard of Engineering Econ, Engineering Management, etc., but what about Engineering Philosophy?
Most of the time, in engineering discussions we talk about “hard information,” that is, facts, ideas, and methods for doing various engineering activities. But behind all that, guiding it, there needs to be a correct philosophy, an approach to life. Late at night, when you are alone in your bed, do you ever think about, “What does it mean that I am an engineer? What does this mean about the way I approach my daily work? What does it mean about the way I think about politics? What does it mean about the way I live my life?”
A recent comment on one of my previous articles points indirectly toward these questions. I do not wish to criticize the person making the comment in the least, but rather to use his comment as a spring-board to get into my reflection on philosophy. The comment read, in part, as follows:
...but we learn in in india from our regular course, book contents are diferent from differnet author, so we have problem which one is correct. for example my project is analysisi of drum brake, the book I preferred for making the project and for formulation is wrong according to some people.
This person is pointing to a misunderstanding of engineering education. He wants an authority that is always correct, so there will be no conflict between one authority and the next. He wants to be able to say that a particular approach is correct because this author said so. What is he missing?
To try to get to that question, let us first look a bit deeper at his complaint. We have engineer W complaining that he wants to execute his project following the methods described by author X, but various others are saying that he should follow the approach given by author Y or the one set forth by author Z. What is engineer W supposed to do?
Assuming that authors X, Y, and Z each describe a different approach to his problem, how should he know which one to follow? Is it possible that each of the authors, X, Y, and Z are correct even though they are different? Well, maybe.
1. It may be the case that each of the authors describes an approach of different accuracy. Perhaps X is describing a simple, “back of the envelope” hand calculation that is only a rough approximation but requires very little effort. At the same time, Y is describing an approach incorporated into a widely accepted standard, and Z is describing a very thorough, detailed analysis (FEA, CFD, elaborate simulation, etc.). Which one is correct? Well, they all are “correct” in their own context. Then the question becomes, what does the project justify? Is it worth spending the resources (time, manpower, etc) for the very detailed approach given by Z, or is a very rough approximation sufficient for the present purposes, something like the hand calculation described by X? In this situation, the “correct choice” is the one that is appropriate to the purposes of the project.
2. Another possibility may be related to the technology involved. For example, imagine that author X is describing a graphical solution while author Y is describing a simple but effective computer solution and Z is again proposing a very involved computer solution requiring massive computing power and software resources. The graphical solution may offer a good bit of insight, but it is necessarily relatively slow and has only limited accuracy. Repeated applications of the graphical methods mean many clean sheets of paper to start again and again. The simple computer solution is likely to be much more accurate and lends itself to repeated application as needed to iterate toward a final solution. The very detailed computer solution can also be used to iterate, but often at very high costs in terms of time and resources. In this case, the simple computer solution described by author Y is likely the optimum approach.
3. There is also the unhappy possibility that the method recommended by author X may simply be in error. We may assume that he would not have published it if he thought it was incorrect, but the fact that it is in a book is no guarantee that it is correct. If this is the situation, then it is clear that the method of author X is to be avoided.
So where does this leave engineer W? The answer is really pretty simple: He should not use any tool that he does not fully understand, both in terms of how it works and what it costs. And this brings us back toward the original question, “What does it mean that I am an engineer?” An engineer is one who applies knowledge. He does not simply use tools without understanding what they do.
This last statement leads into another discussion, that regarding just how fully do you need to understand your tools. We have to recognize that no one can know everything that is known; it is simply too much. That said, it is clear also that the person who tries to drive a screw with a hammer does not understand his tool. One place where we can easily get into difficulties is with the application of commercial computer programs for FEA, CFD, etc. These are highly sophisticated programs, and the internal technical details of their workings is clearly the realm of the specialist. On the other side, the misapplication of these programs have produced some stunningly bad results, leading to catastrophic failures and false alarms. How is an engineer supposed to deal with these?
The first guiding principal is “Do Not Accept Anything Blindly Just Because the Computer Said So.” We must remember that the computer has no brain at all. It is simply a very fast way to make calculations, calculations which can be made correctly or in error. The computer is able to generate errors far faster than anything you could possibly do by hand! You must always, without exception, check computer results for reasonableness. You should also run test cases, cases for which solutions are known by other means, that incorporate as many of the features of you actual problem as possible.
Let us look at a specific case to expand upon this. Suppose that our engineer needs to design a shaft. The shaft is required to transmit certain amounts of power, it has various lateral loads, and in all likelihood has numerous steps along the length (steps are useful for locating items such as wheels, bearings, disks, blades, etc., mounted on the shaft). Our engineer may very well choose to use a finite element program or a specialty shaft design program to assist him in his design work. How will he be able to judge the correctness of the computer results?
In college, he took a course in Mechanics of Materials (sometimes called Strength of Materials) in which he studied shaft and beam deflections and stresses. The problems in that course were, without exception, based on simple geometries. The beam/shaft is usually uniform along the length, and the supports are either simple supports (knife edges) at the ends or built-in ends. The course will usually consider a variety of discrete and distributed loads. How does this relate to the design problem he faces on the job?
1. He should have learned that the boundary conditions are critical to a correct model. Changing from a simple support to a fixed (built-in) support can make a great difference.
2. He should have learned that the corners near a step along the length are essentially dead material; they do not carry much stress or strain at all because of having a free surface on two sides.
3. He should have learned how to combine the effects of different load types by superposition. This will allow him to consider one load, or one group of loads, at a time if that is useful.
4. He should have learned how to combine stresses in order to compute principal stresses and the von Mises stress at a point for failure evaluation.
5. He should have learned about stress concentration at corners, such as a step, and the means to mitigate this problem.
The list above is only a beginning, but the point is, the information from the Mechanics of Materials course is going to be fundamental in his shaft design problem on the job. He may also need to draw on information from Dynamics, Vibrations, and Material Science courses to deal with the whole problem. For this reason, it is absolutely essential that he actually learned the content of these courses. They are not there simply as hurdles to be jumped on the way to a degree; they are the basis for professional engineering work.
When I say “learn the content of these courses,” I mean just that. Really learn, understand, and make the content of these courses your own. This means learn all of the mathematics required to work through and fully understand all of the derivations. Again these are not simply hurdles to be passed; they are the foundations for your career.
Sadly, I have to admit that there are a great many people in engineering positions who have not done this. While I was still an undergraduate myself, I had an opportunity to visit with the director of the state highway department, the man ultimately responsible for the design of all the roads and bridges in the State of Texas. I asked him how much he used calculus on a day-to-day basis. He laughed at me, and told me that he never used calculus. He could not remember any of it. That puzzled me at the time, but I understand it now. This man was no longer really an engineer; he was not competent to design anything at all. He was a paper-pusher, and executive, but he was not an engineer. You can only be an engineer if you know what you are doing!
That brings me back to the comment that appeared on this blog, the complaint about different authorities in conflict. The final answer to that question is simply this: You, the engineer, must be able to correctly identify the proper approach and justify your decision. You can do this if you really know what you are doing, but you will never be able to do it if you don’t know what you are about. You, the engineer, must ultimately be your own authority!