4D Printing: Post-processing for the masses

Abstract

This research investigates the challenges a
user faces in the activation step in shape-changing products. First, previous
research on the topic of 4DP is reviewed and important factors are described.
Namely, activation temperature, print temperature, print speed, and layer
height have a signifi cant impact on the shrinkage of SMPs, during the
activation step in 4DP. These shrinkages can be applied to an object through
the use of varying strategies. These strategies show there are two ways of
applying SMPs to a design, either calculate the shrinkage or create limits with
the use of geometry-based end stops. Lastly, a further review is conducted into
the type of products made with 4DP. These products turn out to be made out of
three categories; fl at-packed, custom fi tment, and energy-absorbing structures.  The second chapter, Material Tinkering &
Exploration, delves into the material characteristics of LW-PLA, showcasing its
utility for shapechanging. LW-PLA can be used both as a passive and active
element, reducing environmental impact by enabling or disabling shape memory through
micro-scale structural changes. This material is then used to fi nd a correlation
in curvature and ratio of active versus passive elements within a design.
Furthermore, the material is used to fi nd the best type of heat source, trying
to create the most consistent outcomes. The oven without convection is then
chosen as it creates the most consistent outcomes by limiting user interaction
and making use of slower response times. 
The following chapter brainstorms ideas that can make use of shape change.
Through the use of criteria and Edison profi les a direction is chosen. This is
the direction of the temples of glasses. Shape change can add to this product
as the temples vary in length to fi t different users. This chapter also
creates two prototypes to be tested, differing in the type of measurement
method.  Lastly, the design is evaluated
through the use of two user studies. In the fi rst study, the focus is laid on
the type of measuring method. The external measurement method comes out as the
most promising as it creates the most consistent outcome with the users. The
second test tries to minimize the error between the targetted length of the
temple and the actual length after the activation process has ended. The result
is an addition of two test samples that educate the user. Through the education
of the user, a consistent result with minimal error can be achieved. The
activation step also requires a homogeneous method of heating the temple, small
deviations in this heating lead to unwanted curvature. This is combatted by creating
a tray, that is delivered together with the temple.