The spring element is connected to the object applying
the force. When an external tension is applied, the spring
element shape deforms/bends. Each type of spring element
has a longitudinal (along the x-axis) and a transversal
(along the y-axis) Poisson effect according to its material
composition. A spring element is usually made of aluminum
or steel and the force applied to it must be within the elastic
range of the material where it responds linearly. If it is
overloaded beyond the elastic limit, it can suffer permanent
damage. Figure 2 shows a metal beam with length x, width
y, that is submitted to a strain ε when a traction force is
applied.