1. Dec 12, 2008

### perfectz

"Normal to the reference surface of the beam remain normal to it and undergo no change in length during deformation"

2. Dec 12, 2008

### Mapes

That's not a sentence as you've written it, so I did some searching. Do you mean "Normals [i.e., normal vectors] to the reference surface of the beam remain normal to it and undergo no change in length during deformation"? It's not a hypothesis, it's an assumption used to simplify elasticity problems. And assumptions, like models, are often strictly wrong but useful.

3. Dec 12, 2008

### perfectz

Ya ya Love's assumption. I am extremely sorry pal. I understood first 3 this one I can't....... Plz help

4. Dec 12, 2008

### perfectz

Does it mean that deformation is not significant enough to affect the normal?

5. Dec 12, 2008

### brewnog

Not sure I understand (your English is a little muddled!), but how's this:

If you apply a force in order to bend a beam, an assumption is made when you perform your calculations. You assume that the force you apply remains normal to the beam's axis (perpendicular to the length of the beam), and that the beam doesn't change in length under deformation (when it's bent).

6. Dec 12, 2008