UC Irvine

This thesis presents an exploration and analysis of the feasibility of two tensegrity systems through a series of optimization studies. First, double-helix tensegrity systems are defined for their application in a package delivery processes as payload carriers that provide impact attenuation for their payload. The architecture of the established double-helix tensegrity payload carrier is defined and modified to enhance flexibility in optimization studies. A dynamic model to simulate ground impact for the payload carriers is derived such that the physical and material characteristics of the carriers are simulated. The dynamic simulation calculates stress and strain in all members of the payload carriers and outputs all member failures. The simulation also performs checks on the carrier to ensure that it has not deformed to flip inwards on itself. Finally, the simulation ensures that the payload within the carrier does not experience forces greater than 10gEto ensure that no damage occurs to the payload from carrier impact. The dynamic simulation is then used to perform a full optimization analysis to optimize the mass and impact attenuation of the payload carrier by varying topological parameters and applying penalties to configurations that experience physical or material failures during the simulation. The MATLAB genetic algorithm is used to conduct the optimization using a fitness score to penalize any configurations that contain material or physical failures as well as any configurations that have a maximum payload deceleration greater than 10gE. An optimization study is conducted using three shapes, cylinder, ellipsoid, and parabola, each carrying a 5 kg payload dropped at a height of 2 m, to find the optimal geometry and topology for a payload delivery application. The parabolic double-helix tensegrity payload carrier obtained the lowest mass of the three carrier types with a structure mass of 2.33 kg while its payload experienced a maximum deceleration during impact of 8.99gE. The ellipsoidal carrier provided the second lightest structure mass at 3.88 kg with a maximum payload deceleration of 6.15gE. Finally, the cylindrical carrier converged to a mass of 5.44 kg with a maximum payload deceleration of 8.71gE. A similar optimization technique is applied to a tensegrity morphing wing that actuates using a twisting tensegrity column design. The tensegrity morphing wing has a greater lift-to-drag ratio than a conventional wing that uses flaps to actuate due to the reduction of induced drag from the elimination of control surfaces. The tensegrity morphing wing replaces control flaps with a tensegrity torsional mechanism to twist the entire wing and create a change in angle of attack. A finite element model of the wing is developed in ABAQUS to simulate a Carl Goldberg Falcon 56 Mk II R/C unmanned aerial vehicle with a wingspan of 142.24 cm and a chord length of 25.31 cm. The finite element model evaluates the maximum twist achievable at an air speed of 20 m/s given that no components of the wing fail from material or structural failure, as determined by ABAQUS. A multi-objective optimization study is conducted to maximize twist angle and minimize wing mass. The multi-objective optimization provided a range of solutions in the form of a Pareto front. Three designs are chosen from the Pareto front to determine the effectiveness of the optimization. Compared to previous design of experiment studies, the optimization was able to provide wing configurations with higher twist angles and lower masses. The highest twist wing design obtained a maximum wing twist of 18.68◦while obtaining a low mass of 1.88 kg.