3D printing of multi-material gripper for tunable rigidity and shape conformance

• Main Author: Cheng, Shi Hui
• Other Authors: Yeong Wai Yee
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/167941
• Institution: Nanyang Technological University

Recent advancements in soft robotics have showcased an increasing importance of gripper design. Although there have been studies and research conducted on the topic of tunable rigidity utilizing lattice structures to overcome current limitations, there is still a gap in exploring and investigating the potential of multi-material lattice structures. This paper aims to address this gap and develop a tunable rigidity gripper that can be easily adapted for various soft robotic applications. This report describes the design considerations, printing, and testing of a lattice structure with a high degree of freedom (DOF). By integrating jamming technology, a gripping effect was accomplished utilizing a multi-material lattice structure. Furthermore, the gripper’s rigidity can be controlled by adjusting the vacuum pressure. Through the additional benefit of using additive manufacturing technology to incorporate multi material structures, a 3D printed chainmail of both single- and multi-materials revealed a range of possible structures with considerably high DOF. Moreover, by utilizing additive manufacturing, it became possible to assess several design iterations through rapid prototyping, creating various samples with different designs. Physical prototypes also assisted in identifying viable designs. In addition, the data collected from the three-point bending tests on the multi-material lattice structure revealed two notable characteristics. Firstly, an increase in the PLA content in the PLA-TPU composite layering ratio resulted in a higher rigidity of the lattice structure. Secondly, the stacking arrangements in the double-layer structure were found to significantly affect the curvature of the structure when subjected to vacuum pressure. In conclusion, the suggested lattice structure design utilizing multiple materials has the potential to achieve novel actuation mechanisms, particularly in the realm of 4D printing. This emerging field involves creating 3D printed structures that can adapt and respond to external stimuli over time, presenting a range of exciting possibilities for future applications. Keywords: Additive Manufacturing, 3D Printing, tunable rigidity, shape conformance, jamming technologies, granular jamming, lattice structure, chainmail, 3-point bending testing.