Modelling and optimisation of the design and topology of flexible frames with rigid joints

Structural optimisation currently relies heavily on methods based on discretisation. In simpler cases like the simulation of frames and trusses, where discretisation is not necessary, only the elongation or compression is considered and the joints are free, like ball and socket joints, in order to avoid bending the trusses. In this dissertation a discretisation free method for the modelling and optimisation of frames is developed which considers bending of the beams along with compression or elongation with joints between the beams being rigid. Rigid joints are commonly the result of welding two beams together or connecting them using mutiple rivets. The optimisation problems, both state and design optimisation, are formulated via the total elastic energy and the work done by external forces. Moreover, for the optimal sizing problem a topological sensitivity for introduction of new beams between any two arbitrary positions in the frame is discussed.