The top and bottom platform of every level is triangular, made up of three
rectangular plates of equal length, fixed to one another. Every level consists of six struts
and six rectangular plates, where in the struts are always at angle with respect to the
plates. The struts are connected to the plates with hinges permitting only a single degree
of freedom. In every level the struts link two different ends of corresponding rectangular
plates in the top and bottom platform.
4.2 Determination of Stiffness
The stiffness of the mast is determined by the application of forces on the three
inner vertices of the topmost platform of the mast and the resulting displacement of the
vertices. The forces are applied along the x, y and z axis and a torque is generated by
applying forces on the inner vertices of the topmost triangular platform in a direction
perpendicular to the central axis. For every mast, forces are applied on three points in the
topmost platform and stiffness is measured as the ratio of the sum of total forces applied
to the average of displacements at these three points.
Kx =- f (4.1)
3 a
Where, Kx is the stiffness along the x-axis, fx is the force applied along the x-axis
and 8 x is the displacement along the x-axis. Similarly the stiffness along the other axes
is determined. The torsional stiffness KTZ is determined as the ratio of the sum of all
torque to the average rotation.
4.3 ANSYS Modeling of the Masts
Every strut in all three masts is a cylindrical tubular member with an outer radius of
0.35 m and an inner radius of 0.30 m. The height of every level in all the masts is 4.9 m