PSI - Issue 42

F. Cesarano et al. / Procedia Structural Integrity 42 (2022) 1282–1290 F. Cesarano, M. Maurizi, C. Gao, F. Berto, F. Penta, C. Bertolin / Structural Integrity Procedia 00 (2019) 000 – 000

1285

4

Table 2: Slicer main parameters

Extrusion width

Nozzle diameter

Eleph. foot

Infill speed

Layer thickness

0.4 mm

0.4 mm

0 mm

85 mm/s

0.2 mm

Perimeters

Solid Layers

Bed temperature

Printing temp.

Fill pattern Rectilinear

0

0

60 °C

215 °C

Figure 1 outlines the complete study process proposed in this paper. In detail, (a) starting from the chosen material (PLA), using the 3D printer (FDM) associated with the slicer, the specimens are produced, thus realizing the transition from permanent to temporary shape; (b) subsequently, the homogeneous thermal load is applied using the gravitational convection oven, triggering the activation of the shape memory effect and the consequent return to the permanent shape, which consists of the programmed shape. (c) The last step uses the obtained results to process the data and compare them with the FEA

3. Results and Validation This section concerns the validation of the chosen experimental pathway and the analysis of the obtained results. The section is divided into two subsections reporting the experimental phases; the first phase concerns the understanding and the validation of the chosen experimental approach. It is constituted by two different comparisons: a first comparison between the bi-material strip model and FEA and a second comparison between FEA (based on classical laminate theory) and experiments. In the second phase, more experiments are carried out to analyze the phenomenon in detail by obtaining support from numerical analysis. Then, a preliminary understanding of suitable approaches for studying the SME is achieved through time and temperature combinations. 3.1 Validation and development of the experimental Methodology The first comparison (Bi-material strip vs FEA) allows us to understand and exploit the theory behind the bending of a bi-material component (analogue to bi-layer) under the effect of a homogenous thermal load. Due to the SME, it is reported in the literature that a PLA bi-layer plate with fibres at 0° and 90° can deform qualitatively like a bi-material strip [2, 5]. Therefore, this first comparison helps to confirm the validity of using the geometrical equation (1). By considering random elastic-thermal properties and generating a bi-material composite component via the Abaqus Fig. 1: Outline of the experimental and analysis process (One-way SME) - (a) PLA specimen production stage with FDM; (b) trigger and activation of shape memory effect in a gravitational convection oven. (c) experimental data processing and comparison