טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentDmitry Vladimirsky
SubjectAnalysis and Design of Microstructures in 3D-Printed Soft
Composites and its Implementation in Morphing Wing
Structures
DepartmentDepartment of Aerospace Engineering
Supervisor Dr. Rudykh Stephan


Abstract

Modern rapid development of additive technologies expands new horizons in the field of soft robotic (subfield of robotics dealing with constructing robots from highly compliant materials) design. These technologies are new, which implementations, in the field of aerospace, are incompletely described.

The research focuses on 3D-printed samples that was produced on the new printer at the aerospace structure lab. This printer can print a variety of plastic types (soft Tango Plus rubber like material and Vero White hard plastic, for example) separately or as a single body. During the printing process the material injected in a liquid state with a layer thickness of 16 microns. After each layer injection is made, the material solidifies using a UV curing. Such process makes perfect adhesion of different materials, thus enabling the user to create a variety of materials named Digital Materials (DM) by mixing hard and soft materials constantly.

The research consists of three main parts. The initial part consists of a set of experiments that were conducted to find the various characteristics of said materials. The results of the experiments showed that the DM responses fit the Quasi-Linear Viscoelastic (QLV) model. Hence, it was used for the numerical model of the sample’s response to local actuation. In the second part, a research was conducted on the global response of the composites, which consists of stiff thick (0.35 mm) layers embedded in a soft matrix. The composites that were produced were made with different angle of layers to the local actuation (by indention), while the composites without stiff layers were used as a control group. The comparison showed that there is a possibility of basic programming of the geometrical configurations, for which amplified global displacement of the structure can be achieved. The results, that were achieved by using numerical simulations, fit experimental study, made using 3D-printed samples. The provided research claimed that the greatest global reaction is in the composite with layers that are parallel to the actuation direction. It was provided using computation of homogenization method, but because of relatively big indention of actuator it did not fit the premise of the method. The research included designing several actuators, which would be beneficial for this type of shape-changing soft structures. Both external and build-in (printed with the composite) actuators, that are based on bi-material memory alloy nitinol, were designed and produced. Unfortunately, because of lack of controllability and the required parts’ dimensions, the presented actuators can only be used for ability demonstration purposes.

The last part of the presented research deals with additional methods of actuating, that was considered and developed. This method includes a single wire actuator (goes through the entire structure) that compresses the structure with inner programmed configuration of stiff inserts in soft matrix. Such method has an array of potential applications, due to the structure’s ability to play the role of a counter-body, by storing elastic energy. Some of the applications are presented in this work.