Morphing aircraft and morphing structure concepts have always interested many researchers and aircraft designers because of its ability to improve the overall performance of an aircraft. One of the most beneficial morphing concept being an improvement in range and endurance by increasing the span of a morphing aircraft wing during cruise and improving the manoeuvrability performance by decreasing the span of a wing.
A common mechanism which can be used to achieve span morphing is cantilever beam type telescopic mechanism. This mechanism consists of multiple beams with one being a main or primary support beam (cantilever type) and the other secondary beams being extending out or retracting inside the primary host beam. Thus by moving the secondary beams over the primary supporting beam, the span of the beam can be increased or decreased.
When the secondary beam traverse along the primary beam, the overall load pattern acting on the primary beam changes. Such a movement of secondary beams can be modelled as an equivalent moving-loads (.ie moving forces, moving bending moments, and moving torque) acting on the supporting beam. These movement of equivalent load, with a definite velocity, induces vibration in the primary beam. This results in a necessity to study the dynamic effects of moving loads and limit the vibrations induced on the beam.
The beam is modelled using the Rayleigh beam theory, for the transverse bending, to incorporate the rotary inertia effects. The bending and torsional response are decoupled and studied separately. The moving loads aremodelled as three types: (i) Non-Inertial, Time Unvarying Load, (ii) Non-Inertial, Time (ii)Varying Load and (iii) Inertial load. The response of the beam is studied primarily in terms of Dynamic Amplification factor (DAF) and velocity of travel.