J.P. Den Hartog Strength of Materials

Hi all ! Been reading this incredible little book on Strength of materials by an amazing engineer J. P. Den Hartog. He has a method of calculating beam deflection by what he calls the Myosotis method. Its absolutely an amazingly simple and quick method which Ive never come across before in any textbook including Timoshenko's work. Anyone ever heard of this method or indeed use it in their work ? I'd be very interested to hear from anyone who knows more about the method and where it derives from.

Thanks all especially eng.Tips its great !!

 

[Lion06]

I am actually going to buy the book (since it is so cheap) and check this method out. That being said, is it any quicker or easier than using the equations right out of the steel manual for the many types of loading conditions and end conditions and then using superposition as required? I can get the deflection of a simply supported beam with a point load and a uniform load in about 40 seconds using the steel manual.
I learned several methods of calculating slopes and deflections in two undergrad analysis classes. Conjugate beam method, double integration, I used stiffness matrices for something but I'll be damned if I can remember anymore, virtual work, there may be a couple more that I am forgetting, and Castigliano's method (my personal favorite).
If I had to solve a rather difficult deflection problem or indeterminate problem by hand, I would definitely use Castigliano's method.

 

[civeng80]

You may have a spreadsheet for solving redundant beams OK. Thats not the same as finding deflections.

Structural engineers have to design for strength and serviceability i.e. they have to assess deflection. In a simply supported beam I wouldn't be using a computer or a spreadsheet. I would simply do a hand calculation using a table or design aid I would have around. Some can be pretty time consuming and no spreadsheet is around to solve them, so why not use this method ? No need to use a slide rule.

One further point to write a spreadsheet for beam deflection you would need to use one of these methods anyway.

My point was mainly directed to structural engineers who have a knowledge of Mechanics of Solids and the traditional textbook methods of solving for deflections as I stated above (Another method in the list may be Castiglianos strain energy method).

This is simply another method.

At the end of the day you use whichever method you feel comfortable with.

Thats all from me !

 

[Lion06]

Can you please post an example for a 10' long beam with EI=2900000 k-in^2 and with a uniform load of 0.5 k/ft and a point load at midspan of 2 kips? Or some other example that you already have worked out.

 

[rb1957]

takes for civeng80, right ?

 

[Lion06]

yes, the request for an example was for civeng80.

 

[civeng80]

Just buy the book if you wish and look at the method.

For your example as I said I would look up solutions in standard solutions (2 of for different load cases) and then use superposition as you and I have already suggested.

I repeat myself here. Mysotis is just another method (different albeit!) from the classical methods such as those already mentioned. The standard solutions used these methods to work out deflections so indirectly your using these methods in calculations if your using design aids.

I repeat myself again

At the end of the day use whichever method you feel comfortable with. StructuralEIT if it takes you 40 seconds to calculate a deflection then continue this method and dont bother buying the book.

Cheers !

 

[civeng80]

StructuralEIT

If you like Castigliano's method for difficult problems then Myosotis is definitely worth looking at in my opinion.

My personal favourite for the difficult problems was and still is virtual work method and it can be used for varying UDL as well (with a table of integrals!)

If your getting the book you'll be glad you did for the money it cost. Even Castigliano's method is very well covered as is many other topics.

Anyway thats enough from me now !

Cheers Mate !

 

[amorrison]

Hartog - just some "average" MIT prof.

http://en.wikipedia.org/wiki/J._P._Den_Hartog

 

[Rici]

You can find here more about Biezeno's work:

http://www.gl.iit.edu/wadc/DigitalCollection/1970/AFFDLTR70-025.pdf