Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Why study 'Theory of Elasticity'

  1. Aug 15, 2012 #1
    Hi.
    What is the point of studying Advanced Elasticity course apart from strength of materials/solid mechanics?? One of my friend says that there's no need to study this as the content of this course is rarely used in industrial practice. He says that the (Stress Analysis) Engineers merely use software to do the analysis...so why study Theory of Elasticity??
     
  2. jcsd
  3. Aug 15, 2012 #2
    I have no idea what is contained in your advanced elasticity course, since you haven't told me.

    But if you find it uninteresting why are you studying it?

    What branch of engineering are you actually studying, you have posted in the mech engineering forum so I will assume this for an answer?

    Of course stress analysis engineers use software, as do most engineers these days.

    How do you think they go about analysing the stress within a complicated shape or the contact stresses of two gears or whatever?

    What do they do when they have to leave the tables provided by Roark and the like?

    They have to work it out from first principles. Very often these days that means establishing a finite element mesh but they still have to use good engineering judgement first to establish a suitable mesh and then to apply suitable functions to it. Finally they have to understand the output and be able to tell when it is right and when it is wrong.
     
    Last edited: Aug 15, 2012
  4. Aug 15, 2012 #3

    AlephZero

    User Avatar
    Science Advisor
    Homework Helper

    Nope. Bad engineers merely use software.

    Good engineers understand what they are doing, and know when the pretty pictures from the software are useful and when they are nonsense.
     
  5. Aug 15, 2012 #4
    While it may seem like we've got these magic boxes that spit out all the answers to our problems, this is not quite true. Numerical software has the tendency to create problems nearly all the time. Instabilities, wrong answers, etc etc etc. You have to know the theory, and you have to know it pretty well to be able to realize what's going wrong and how to solve it. What are you going to do when you get hourglassing effects or shear locking if you don't know the theory of how FEA works? Ok, this example is not directly related to elasticity, but the same goes for advanced elasticity. FE codes are based on continuum mechanics, that is advanced elasticity (which I assume may be what you're studying?). To solve problems, you need to know how they could come about, and for this you need to know the theory.
     
  6. Aug 15, 2012 #5
    Finite Element analysis is not the only form of mesh analysis.
    Finite Difference analysis is another.

    The difference is that FD analysis is a direct method where numerical substitutions are made directly into the actual (differential) equations.
    However FE analysis is an indirect method in that it is also based on variational calculus and substituting (simpler) functions for the actual equations.

    Of course there are yet other methods for the mesh, such as boundary element methods, based on Greens theorems (or Gauss's theorem).

    Go well
     
  7. Aug 15, 2012 #6
    Is your friend a professional engineer with practical solid experience in the field you describe? Or not?
    It is wise to discern where advice comes from at times. For some industries the software package is enough. For others testing and re-analysis is necessary.

    By the way, do you think software programs just write themselves by magic?
     
  8. Aug 16, 2012 #7
    Thanks all.
    I now have some very good points to defend against him.
     
  9. Aug 16, 2012 #8
    If I were to give a small analogy, Can you read a foreign language without knowing the language?
    Its so similar to that. You will never be able to understand why you have got the output using a software without knowing the basics.
    Infact any software for that matter to uses these laws. They are based on it.
    The GUI is created by software engineers, But the way it works uses mechanical Engg.
    So I advise you to study the subject as it is necessary.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook