Spring class

A simple 1d spring element for teaching the finite element concepts of element stiffness and assembly.

Parent class

The spring is defined as the horizontal connection between two nodes ndi and ndj.

The mechanics of the element is described by length change

\[\delta = U_{j} - U_{i}\]

and internal force

\[f = c\:\delta\]

where \(c\) is the spring stiffness in force per length change.

class femedu.elements.linear.Spring.Spring(ndi, ndj, c=1, label=None)

A 1d linear elastic spring element.

This element only uses the x-coordinate and the displacement in x-direction (‘ux’).

getInternalForce(variable='')

Helper function used by the plotting functions.

Returns:: (s,f) , two lists containing start and end values of normalized position and internal force, respectively, at both the start and the end point of the line of action.

updateState()

called to compute internal force and current nodal reactions for equilibrium test