Article contents
Some General Considerations on the Natural Mode Technique
Part II. Large Displacements*
Published online by Cambridge University Press: 04 July 2016
Extract
We continue our fundamental discourse on the natural modes in an element and extend our considerations to large displacements. First, we present a general procedure for establishing the so-called geometrical stiffness kG, when the natural modes of the complete element are given. The theory is a substantial generalisation and clarification of the method initially given in refs. 2 and 3 and shows that in establishing the modification to the transformation matrix aN it is necessary to ignore the contribution of the natural modes, which cause rotation at the nodal points but no displacement there. The point is subtle and was not made in ref. 2, although the applications given there are correct. As an example, the geometrical stiffness of a straight beam in space with all degrees of freedom is established. There follows the extension of the geometrical stiffness concept to a sub-element. This is of great practical significance for two reasons. First, it allows to derive the geometrical stiffness of elements of complex shape and behaviour, e.g. curved beams in space subjected to normal forces, bending moments and torque.
- Type
- Supplementary Papers
- Information
- Copyright
- Copyright © Royal Aeronautical Society 1969
Footnotes
Part I was published in the March JOURNAL pp 218 as Technical Note 19.
References
- 7
- Cited by