The aim of this position paper is to identify a specific focus and the major challenges related to the human-centered artificial intelligence (HCAI) approach in the field of Industry 5.0 and the circular economy. A first step towards the opening of a line of research is necessary to aggregate multidisciplinary and interdisciplinary skills to promote and take into consideration the different aspects related to this topic, from the more technical and engineering aspects to the social ones and the repercussions in terms of sustainability. The proposal and vision of this preliminary work is to identify and discuss a suitable field for such interaction. This field has been identified, specifically, within additive manufacturing (AM) in the context of Industry 5.0. Additive manufacturing (AM), is a disruptive opportunity for more sustainable production systems that can be better optimized with AI, becoming an ideal platform for interconnection between different levels of application and integration of HCAI concepts, and at the same time able to prove them. In this context, two prospective areas with a high application impact of HCAI are those of AM-oriented supply chain and product customization in the AM field, enabled by a plethora of recently emerging technologies such as the internet of things, cloud and edge computing, and next-generation networks (5G). The paper concludes with the challenges HCAI poses to public policymakers, who face significant policy challenges in regulating artificial intelligence, and addressing the socioeconomic and technological impacts. Decision-makers are required to address these challenges by adopting some tentative policy recommendations.

Even though clinical observations were not within the aim of this study, our findings indicate that a better understanding of the correlation between mechanical properties and thickness could lead to a more rational design and use of these membranes in the face of specific clinical cases.

Shape memory properties of PET (polyethylene-terephthalate) foams have been evaluated for two different foam densities. Samples were subjected to multiple memory-recovery cycles along three different directions to measure the effect of foam anisotropy on static mechanical and shape memory properties. The memory cycle was performed by uniaxial compression tests at room temperature. Despite these severe conditions, PET foams demonstrated very good shape memory behavior with shape recovery always higher than 90%. Due to cycling, the mechanical performance of foam samples is partially reduced, mainly along the extrusion direction of the foam panels. Despite this loss of static performance, shape memory properties are only partially affected by thermo-mechanical cycles. The maximum reduction is 10% for shape fixity and 3% for shape recovery. The experimental results are particularly interesting considering that compression tests were undertaken at room temperature. Indeed, PET foams seem to be optimal candidates for self-repairing structures.

A shape memory polymer composite (SMPC) unit has been manufactured with embedded heater. The structure of the SMPC unit has been designed to allow reaching high recovery loads with a reduced size of the functional device. The unit is a composite sandwich with four carbon fibre reinforced (CFR) plies, two SMP foam cores, and one SMP interlayer. In the mid-plane of the sandwich the heater is integrated, being immersed in the SMP interlayer. The adopted manufacturing procedure was able to provide the necessary consolidation in one step moulding thanks to the use, during lamination, of pre-formed SMP cores, and uncured SMP powder for the interlayer. The SMP cores were manufactured by solid state foaming of the same SM epoxy powder. SMPC laminates, without the embedded heater, were also manufactured for testing as well as traditional four-ply CFR laminates. Several tests were carried out for temperature calibration and for investigating SM properties of the SMPC laminates and unit. Dynamic mechanical analyses, hot bending tests, and microscopic observations were performed on CFR and SMPC laminates. It was found that the SMP layers reduce the glass transition temperature of the laminates as well as the transition onset temperature and, above all, the extension of the transition range thus providing the trigger effect to the SMPC transition. Double-cycle SM tests were carried on the SMPC unit at different temperatures from 160 °C to 190 °C. The unit (20 × 45 mm²) was able to exert recovery loads over 7.4 N almost independently from the temperature and without any evidence of failure after several repeated tests. High values were measured also for the shape fixity and shape recovery which were, on average, higher than 96% and 95%, respectively.

Foams of polycaprolactone (PCL) and microbial polyester (poly-hydroxybutyrate-hydroxyvalerate, PHBV with 10% mol PHV) were produced by particulate leaching in an urea preform and subsequent preform dissolution in distilled water. Films were also cast to compare mechanical and shape memory performances. SEM observations of foam sections showed that a homogenous microstructure was obtained with good replication of urea particles. Cylindrical PHBV samples (porosity about 90%) were used for shape memory tests in compression mode and a good behavior was observed. After training, 100% shape recovery can be achieved if a maximum 30% compression is applied.