Procedia CIRP最新文献

For decades, fossil-based materials have formed the basis of an almost endless range of technical products. Through variable chemical composition and several additives, especially plastics can have a wide range of properties, which form the basis for the diversity of plastic-based products. While this variability enables many sustainability strategies, such as lightweighting, it is also impeding a fully circular economy. Therefore, in recent years, a number of new raw materials have been developed, but they can only cover a very limited part of the wide range of properties of fossil-based plastics. Another promising class of materials are composites based on fungal mycelium.

However, these are mainly limited to the consumer sector, e.g. vegan leather, where there is smaller demand for durability, functionality etc. The step from consumer to engineering materials require the production (or growth) process to be reproducible within the necessary quality requirements. Cyber-physical production systems have the potential to realise necessary technical qualities despite e.g. quality fluctuations of the raw material and production processes that are susceptible to interference. For this reason, this paper analyses the state of the art in production of mycelium based composites, shows the existing gaps and draws a vision to close these gaps.

This paper presents a flexible digital twin framework tailored for the biomanufacturing of advanced therapeutic medicinal products (ATMPs), particularly focusing on chimeric antigen receptor T cell (CAR T cell) therapy. CAR T cell therapies face significant challenges in the management of their personalized and complex biomanufacturing processes. To tackle these issues, we propose a novel software framework for a digital twin system aimed at digitalizing, monitoring, and managing the physical production processes. The framework has a hierarchical architecture that methodically organizes production into distinct abstraction levels: processes, tasks and skills, and microservices. This layered architecture simplifies the modeling of complex biomanufacturing production and ensures that each component can be individually updated without disrupting the overall system. Furthermore, the digital twin framework integrates both manual and automated operations within a unified system, accommodating varied requirements of diverse tasks in production. The framework’s flexibility enables easier adaptation to dynamic technological advancements and allows for swift modifications in production processes, making it a sustainable and resilient digitalization infrastructure for ATMP manufacturing.

The interest in Nitinol (NiTi) as biomedical material is growing thanks to its unique properties, particularly shape memory and superelasticity. Recently, additive manufacturing (AM) has emerged as an alternative to fabricate superelastic NiTi biomedical parts. However, when using AM to fabricate NiTi parts, a proper heat treatment must follow, recommended not only to alleviate the AM-induced residual stresses, but also to develop a suitable microstructure to enhance the material superelasticity. This heat treatment is expected to modify also the NiTi corrosion behavior, which must be evaluated since corrosion may lead to the possible harmful release of nickel ions in the human environment.

In this framework, the objective of the paper is to assess the mechanical and corrosion properties of a Ni-rich NiTi fabricated by laser powder bed fusion before and after heat treatment. To this aim, nano-indentation was used to evaluate superelasticity, whereas electro-chemical tests provided the corrosion potential and current density. The results of the analyses show that both the mechanical and corrosion characteristics were related to the peculiar microstructural features induced by the AM and heat treatment steps, nevertheless ageing at 600°C was the best in terms of superelasticity, while aging at 300°C assured the highest corrosion resistance.

Biointelligent manufacturing represents one of the most promising innovation paths towards a sustainable restructuring of industrial production. In doing so, it assumes significantly changing framework conditions for the production of a wide variety of goods. A recurring element is the decentralization of value chain design, i.e. an increasing shift of the focus of value creation to the customer. While the concept of decentralization has been discussed in the context of systems and organization theory, green supply chain and life cycle management for quite some time, recent studies suggest that especially biointelligent manufacturing systems might represent a promising technological opportunity to truly realize this goal. However, up to now the concept appears somewhat vague, as neither the validity of the assumption of increasing decentralization nor the extent to which a reduction of supply chain length results in an improvement of environmental impact is resolved. This paper is intended to provide a foundation for the advancement of the research area by analyzing the state of knowledge and uncovering logical misconceptions. Although the findings indicate a clear technical decentralization potential of biointelligent manufacturing by various examples, a comprehensive dissemination as small-scale production units in industrial practice remains unlikely due to prevailing organizational and socio-political barriers.

Bone drilling poses intricate challenges due to its high hardness, strength, and anisotropic composite structure. In the dynamic field of orthopedics, advancing surgical drilling techniques is imperative for optimizing precision and implant stability. As drilling methods have progressed from conventional to robot-assisted machining, some new possibilities are now appearing. While orbital drilling has been pivotal in aerospace for reduced forces and superior hole quality, its application in bone drilling remains unexplored. This study pioneers the introduction of orbital drilling for bone machining, aiming to unveil its potential to improve processing quality. Experimental investigations were conducted on cortical femur bone to evaluate its mechanical behavior and the geometry of the holes, encompassing parameters such as hole aperture, roundness, cylindricity and delamination. Employing full factorial statistical analysis, the study systematically elucidates the influence of cutting speed and feed rate on hole quality. Results reveal the potential of orbital drilling in mitigating its defaults and could significantly contribute to improving surgical outcomes in orthopedic procedures.

Recent innovations in Drug-Eluting Stents (DES) technology have led to the development of new stents with further reduction in strut width, the ultrathin DES, with struts thinner than 70 µm. Ultrathin DES may further improve the efficacy and safety profile of Percutaneous Coronary Intervention (PCI) by reducing the risk of target-lesion and target-vessel failures compared to the current-generation DES. However, the ultrathin DES metallic platform still presents some associated problems, such as biofilm formation, infection, and migration, all related to the cellular response.

The present work aims to produce an ultrathin permanent polymeric platform for a new generation of polymeric drug-eluting stents (PDES). In this work, the cellular response was compared with the traditional stainless steel (SS316L) and polycaprolactone (PCL) to determine whether these polymers could address this challenge. An innovative method of tubular 3D micro stereolithography tubular (ST3DT) was used. Different PDES platforms were fabricated with different polymeric materials (based on polyurethane and urethane dimethacrylate). Subsequently, HFL1 fibroblasts were seeded on the PDES, PCL and SS316L for 3 days. The findings from the assays of cell biocompatibility and proliferation (75%PCL), coupled with the successful fabrication of stent struts below 70 µm using the Surgical Guide resin and the ST3DT method, suggest that resin is a promising candidate for a PDES.

In automated material flow, in a wide variety of areas, the primary goal is usually to handle a wide spectrum of components as time- and cost-efficiently as possible. In view of the current and future challenges in industrial production, it is becoming apparent that ecological requirements are becoming increasingly important in automation solutions. For example, in form of resource efficiency, transformability and material efficiency. In this context, especially materials handling technology is subject of various optimization approaches, as no value is added to the part handled. The question: "How does material flow occur in nature?" thus offers biologically inspired approaches to thinking about transport in the industrial sector. This paper first presents a selection of concepts or existing mechanisms that are adaptable in materials- handling technology and have been developed based on a biological model. In the second part of this paper, a new concept is presented that is modeled on peristalsis as a transport mechanism. The approach presented here uses tensegrity-structures for assembly, which are characterized by their high material efficiency and flexibility. The transport movement is achieved by peristaltic typical contraction or relaxation of the respective structure parts.

In rail vehicle construction, austenitic stainless steels are used to achieve lightweight design concepts, as the higher specific strength of the material allows the thickness of parts to be reduced. However, when these are welded to create complex structures, increased welding distortion occurs even with low-heat joining processes such as laser beam welding.

In order to reduce distortion, an in situ low transformation temperature (LTT) effect has been achieved using commercially available materials rather than specially manufactured LTT alloys. The LTT effect introduces compressive stresses into the weld seam, which counteract the formation of welding distortion due to tensile stresses. However, in the case of complex structures, several other factors influence the formation of distortion. The influence of the LTT effect and other factors such as tack welding, clamping and cooling conditions were analysed by distortion measurements and a maximum distortion reduction was determined.

Laser Metal Deposition (LMD) uses laser energy and powder material to create structures on existing components. It is capable of producing cost-effective multi-material compositions, such as reinforcing metals with ceramic particles for improved wear resistance. However, the use of dissimilar materials often leads to defects, particularly delamination. Previous studies have found a connection between these defects and specific airborne acoustic emissions (AE).

To mitigate the impact of defects, extensive optimization of process parameters and real-time process monitoring are recommended. For AE, precise localization of defects is crucial besides to time- and frequency-resolved information, especially while producing multiple components on a substrate material.

This study evaluates multi-sensor arrays for the localization of delamination defects. The research investigates the influence of localization algorithms and array patterns on the accuracy and reliability of defect localization. Experiments were conducted on a test platform with simulated acoustical events to determine the most suitable localization setup.

In the realm of laser-based powder bed fusion processes with metals (PBF-LB/M), spatter formation serves as a crucial stability criterion. However, existing analyses often adopt a qualitative approach, hindering meaningful comparisons between processes. The quantitative investigation of the advantages of beams with non-Gaussian intensity distribution as well as multi-beam processing strategies with regard to spatter formation is still largely unexplored. To address this gap, we present an experimental setup utilizing high-speed videography and individual particle tracking to measure spatter characteristics, count size, ejection angle, and velocity, within the PBF-LB/M process conditions. The investigation deals with focused and defocused Gaussian beams, a beam with ring-shaped intensity as well as processing with two coupled Gaussian beams for the PBF-LB/M of nickel-base alloy 625.