Theoretical and Experimental Evaluation on Specific Stiffness of a Integrally-Shaped Lightweight Honeycomb Robotic Arm

抄録

Space robotic arms should possess lightweight, high rigidity, and compact. To achieve this, we focused on honeycomb sandwich structure. The honeycomb sandwich structure is already put into practical use as plate, while its strength properties in rod shape have not been investigated precisely. In our project, the strength properties of honeycomb sandwich structure in rod shape have been explored. In the previous research, the experimental piece was made by glued FRP plates and aluminum honeycomb core and exfoliation persisted throughout experiment. To overcome this problem, we introduced a 3D printer and shaped the experimental piece integrally. A test piece model is created on 3d CAD software “Creo” to apply theoretical calculation by using finite element analysis (FEM) software “Creo simulate” and to form experimental piece by using a 3D printer “MakerBot Replicator +.” Bending stiffness and torsional rigidity are evaluated through theoretical and experimental analysis. For comparison, the benchmark is SRMS (round pipe shape), and the comparison is made based on the stiffness per unit weight (specific stiffness). A finite element analysis was performed and the honeycomb structure and SRMS were compared. The torsion test and the bending test were performed three times and averaged. The results of the bending test and the torsion test of the honeycomb structure were compared with the analysis results. Theoretical analysis shows that the robot arm using the honeycomb sandwich structure has some advantages over the conventional round pipe type arm. Moreover, the ratio of the experimental value to the analytical value is stable by the integral shaping, although it is about 0.5, and it is thought that the actual rigidity can be predicted to some extent from the analytical value in the future. According to these results, validity of honeycomb sandwich structure for robotic arm is confirmed.