3D Printed Hydraulic Actuation

3D Printed Hydraulic Actuation: Design and Evaluation of a 3D Printed Hydraulic Actuation System

Tiel Groenestege, Jurjen (TU Delft Mechanical, Maritime and Materials Engineering)

Smit, G. (mentor)

Delft University of Technology

Mechanical Engineering | BioMechanical Design

2021-01-14

Objective: The objective of this study was to develop and evaluate a 3D printed hydraulic actuation system, applied in a multi-articulate upper limp prosthesis. The prosthesis was designed to produce sufficient pinch force to be competitive with comparable devices (30 N), and weigh less than a human hand (<0.43 kg). The actuator should function at a high operating pressure (>1.4 MPa) and be compact, such that it fits within the mechanism of the hand. Method: The prosthesis was designed according to a modified V-model design methodology. A prototype was made that embodies the index finger, thumb, and part of the palm. The structural parts were printed using FDM. The actuators were printed in a single step using SLA, requiring only cleaning and curing. To evaluate the performance of the actuators, a set of measurements was carried out, measuring geometrical accuracy, static pressure, and friction in the cylinder. The prototype was tested on pinch force, closing time and weight. Results: Cylinders that are printed at an angle of 90 degrees with respect to the build plate, have a higher roundness that cylinders that are printed at 45 degrees. The actuators were tested at pressures of up to 4.5 MPa, showing no signs of plastic deformation, and have a theoretical maximum pressure of up to 5.9 MPa. While lifting a mass of 6.49 kg, a cylinder friction force of 25.7 N was measured, which is higher than expected. The prototype could reliably deliver a pinch force of 30 N, with a maximum measured value of 41 N. When operating at high pressures, leakage through the piston O-ring seal was not prevented. Conclusion: This study presents the first hydraulic actuation system that is fabricated entirely with 3D printing. A prototype was built to demonstrate that the prosthetic hand that is designed, is able to produce a pinch force of >40 N, showing that it can compete with similar devices. Its mass (0.35 kg without pump and battery) is less than that of a human hand. Controlling friction and leakage remains a serious concern due to the geometrical accuracy of 3D printing. Future possibilities are increased customization and reduced fabrication cost of hydraulically actuated mechanical systems.

3D Printing
Additive Manufacturing
Hydraulic Actuation
Upper limb
Prosthesis

http://resolver.tudelft.nl/uuid:3eeaf15b-d516-4bde-8eb1-e8e6d3f753c5

2023-01-14

Student theses

master thesis

© 2021 Jurjen Tiel Groenestege