In this paper, the structural efficiency metrics for integrated selection of layup, material, and cross-section shape in laminated composite structures are used to simplify a composite robotic structure's design. In this approach, the design chart for selecting material, shape, and layup was developed using axial, bending, torsional, and mass indices. One of advantages of these graphs is that various parameters in design of laminated composites such as the fibers’ direction, number of layers independent of lamina thickness can be examined to simplify the design. The results are generated for two different types of envelopes to analyze various cross-sections and sizes on design accuracy. Finally, for design of a robot arm with laminated composite, a design chart application was exploited. This technique could provide useful data for design of a robot structure.An aluminum-based manipulator designed by our research group can carry weights of up to 15 kg with a reach of about 2 m. The inertia mass, bending, and torsional stiffness of the manipulator contribute to motors required power and robot dynamic and displacement; this leads us to need for lightweight parts. These parts could be manufactured by CFRP materials to reduce weight.Several optimization methods, such as genetic algorithm and particle swarm optimization have been used to obtain best values for fiber directions and number of layers. These results would lead to optimal values for weight, axial or bending stiffness and strength. However, designing a composite structure for robot with advanced composite materials is challenging. The large amount of design parameters for laminated composites and complex non-linear material behavior is the main challenge. Therefore, it is necessary to propose a design strategy to integrate advanced laminated composite materials into robot design.Ashby introduced a well-known material property charts that plot material indexes on charts to ease material selection, especially at preliminary design stage. He points out that engineering material properties can be mapped, displaying ranges of mechanical behavior they offer. In each map, some spaces are filled, and some gaps exist. These gaps could investigate for developing materials with new properties.By introducing constraint indices describing combined demands from spatial limitations and other requirements (like stiffness), performance indices attain relatively simple mathematical forms, facilitating identification and ranking of possible shape-material combinations.Shape transformers methods have been used mainly to evaluate performance of beams as a first part for creating a complex structure. Mapping a beam structural performance has been developed for different loading scenarios.Formula and charts were generalized for single and multi-criteria selection of light-weight shafts subjected to combination of bending, shear, and torsional loads. This approach was to make some graphs that can show the performance of the whole range of cross-sectional shapes for each material under single and multi-criteria.Selection graphs developed for laminated composite beam under bending and torsional loading. The equations for calculating equivalent bending and torsional stiffness for different cross-sections such as circular, square, Z-beam and I-beam were carried out based on Kollar’s works.In this paper, we extended previous research work for two different envelopes: the first envelope has a square shape, and the second envelope has a rectangular shape. Secondly, axial efficiency graphs and bending and torsional efficiency graphs developed; they were compared to previously reported works; the bending efficiency design chart for both cross-section axes in envelope two mapped. Thirdly, a full detailed finite element analysis is presented to evaluate analytical results. Finally, selection graphs are used to design a robot structure using composite materials, which may help decrease complexity of designing a composite structure.

Optimum Selection of Thin-Walled Laminated Composite Structures in Robot Design

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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