Design and evaluation of 3D-printed fluid-controlled actuators with integrated valves

Master thesis (2022)

Authors

B. van der Windt Mechanical Engineering

Contributors

H. Vallery Biomechatronics & Human-Machine Control - Mechanical, Maritime and Materials Engineering (supervisor 1)
G. Smit Medical Instruments & Bio-Inspired Technology - Mechanical, Maritime and Materials Engineering (supervisor 2)
Sven Müller (coach)
Faculty
Mechanical Engineering
Copyright: © 2022 Bob van der Windt
3D-printing Additive manufacturing Pneumatic actuators Hydraulic actuators Fluid-controlled actuators Lower extremity prostheses Fluid-controlled prostheses Integrated valves
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Published Date

02-11-2022

Language

English

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Faculty

Mechanical Engineering

Abstract

Fluid-controlled actuators are widely used in lower limb prostheses. Most fluid-controlled actuators have valves integrated into the cylinder systems and require complex manufacturing steps, making these systems expensive. A cost-effective production method for these complex actuator valve systems is 3D-printing. The goal of this research is to study the possibility of creating a pneumatic and hydraulic cylinder with integrated valves using 3D-printing and evaluate their performance. A 3D-printed pneumatic cylinder with integrated valves was designed, manufactured and tested on static and dynamic leakage for different pressure levels on a designed test rig. To evaluate the performance, the leakage data was compared with the performance of a commercial pneumatic cylinder. A 3D-printed hydraulic cylinder was designed and built according to the earlier design insights. The 3D-printed hydraulic cylinder was tested on hysteresis and internal and external leakage in open and closed valve mode. Overall the commercial pneumatic cylinder performs better on static and dynamic leakage. In static leakage, a maximum pressure loss of 0.0095 MPa was measured at 0.6 MPa starting pressure after 20 minutes in the 3D-printed pneumatic cylinder. In dynamic leakage tests, a larger pressure difference of 0.035 MPa is measured at 0.5 MPa after 20 minutes in the 3Dprinted cylinder. The higher leakage profiles of the 3D-printed cylinder are caused by a difference in roughness and clearance of the sealing seatings causing movement of the seals. The 3D-printed hydraulic cylinder did not work as expected with 20 N force for moving the cylinder over its stroke, internal leakage of 0.007 MPa at a 0.01 MPa dynamic test and an average external leakage of 8.7 mL after 20 minutes. The tests gave important insights into sealing selection, which was not optimal for the hydraulic application. All in all, this study shows that it is possible to create functional 3D-printed pneumatic cylinders for static applications. Thereby it gives important design insights into improving the performance of 3D-printed pneumatic cylinders for dynamic applications and 3D-printed hydraulic cylinders.