Efficient design of piezoresitive sensors based on carbon black conductive composites

Flexible and stretchable sensors are widely investigated taking into account their potential for wearable electronics, such as electronic skin, healthcare monitoring, human-machine interfaces, and soft robotics. In this contribution, highly sensitive conductive polymer composites (CPCs) for piezoresistive sensing are summarized, considering a straightforward manufacturing process based on extrusion of thermoplastic polyurethane (TPU) and/or olefin block copolymer (OBC), carbon black (CB), and additionally polyethylene-octene elastomer (POE) grafted with maleic anhydride (POE-g-MA). The design of the formulation variables is successfully performed to enable both low and high strain sensing, as highlighted by both static and dynamic testing

3D printing conditions determination for feedstock used in fused filament fabrication (FFF) of 17-4PH stainless steel parts

Fused filament fabrication combined with debinding and sintering could be an economical process for 3D printing of metal parts. In this study, compounding, filament making and FFF processing of a feedstock material containing 55 vol. % of 17-4PH stainless steel powder and a multicomponent binder system are presented. For the FFF process, processing windows of the most significant parameters, such as range of extrusion temperatures (210 to 260 °C), flow rate multipliers (150 to 200 %), and 3D printing speed multipliers (60 to 100 %) were determined for a constant printing bed temperature of 60 °C

Advances in modeling transport phenomena in material-extrusion additivemanufacturing: Coupling momentum, heat, and mass transfer

Material-extrusion (MatEx) additive manufacturing involves layer-by-layer assembly ofextruded material onto a printer bed and has found applications in rapid prototyping.Both material and machining limitations lead to poor mechanical properties of printedparts. Such problems may be addressed via an improved understanding of thecomplex transport processes and multiphysics associated with the MatEx process.Thereby, this review paper describes the current (last 5 years) state of the art modelingapproaches based on momentum, heat and mass transfer that are employed in aneffort to achieve this understanding. We describe how specific details regardingpolymer chain orientation, viscoelastic behavior and crystallization are often neglectedand demonstrate that there is a key need to couple the transport phenomena. Such acombined modeling approach can expand MatEx applicability to broader applicationspace, thus we present prospective avenues to provide more comprehensive modelingand therefore new insights into enhancing MatEx performanc

Fatigue crack propagation in a component produced by additive manufacturing of polymer materials

project m- IPMinfra (CZ.02.1.01/0.0/0.0/16_013/0001823

Experimental testing and process parametrization

In this chapter, a characterization to the resulting FDM-printed parts and hybrid manufactured, essentially in terms of mechanical properties, is exposed and discussed. Once evaluated the polymeric thermal and/or mechanical response of the neat filaments, we were able to move forward with the mechanical characterization of the different printed parts developed under different methodologies and distinct purposes. After all this, the performance of hybrid trials in order to evaluate system functionalities, as well as hybridization strategies associated with the presence of AM supports during milling and layer adhesion on the top of a completely cured and machined surface was pursued. Additionally, it was also studied advanced preprocessing methods such as adaptive or curved slicing assessed in the experimental hybrid system with a special attention to the constraints of using long or continuous carbon fibres. All the experimental methodologies carried out and obtained results are described in detail herein.The authors acknowledge the funding received by Project POCI-01-0145- FEDER-016414—FIBR3D, co-financed by COMPETE 2020 and LISBOA 2020, through Fundo Europeu de Desenvolvimento Regional (FEDER) and by National Funds through Fundação para a Ciência e Tecnologia (FCT)