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A number of finite element formulations involving discontinuous weighting functions have been tested against analytic solutions for a steady scalar convection—diffusion problem at intermediate Peclet number, with a ‘hard’ downstream boundary condition. The emphasis is on extending these methods to isoparametric bilinear and biquadratic elements. In order to do this a procedure is given for the exact calculation of shape function Laplacians. Having confirmed the success of the Brooks—Hughes streamline upwind Petrov—Galerkin (SUPG) method for isoparametric bilinear elements, formulations for biquadratic elements are examined. Galerkin least squares offers little advantage over SUPG in the test problem. The generalized Galerkin method of Donea et al. gave excellent results, but because of concern over the possibility of cross‐streamline artificial diffusion in some cases, a strictly streamline formulation incorporating the optimal parameters of Donea et al. is proposed. This gave excellent results on a sufficiently refined mesh.

This paper gives a review of the finite element techniques (FE) applied in the area of material processing. The latest trends in metal forming, non‐metal forming, powder metallurgy and composite material processing are briefly discussed. The range of applications of finite elements on these subjects is extremely wide and cannot be presented in a single paper; therefore the aim of the paper is to give FE researchers/users only an encyclopaedic view of the different possibilities that exist today in the various fields mentioned above. An appendix included at the end of the paper presents a bibliography on finite element applications in material processing for 1994‐1996, where 1,370 references are listed. This bibliography is an updating of the paper written by Brannberg and Mackerle which has been published in Engineering Computations, Vol. 11 No. 5, 1994, pp. 413‐55.

A tailored graphical user interface (GUI) for finite element analysis, fully integrated into Microsoft Windows 3.1, has been developed. The current application is the simulation of flat sheet extrusion of thermoplastics, but many of the features would be common to a wide range of finite element analyses. Microsoft’s C/C++ Professional Development System 7.0, including the Software Development Kit 3.1 (SDK), has been used as the programming tool for the GUI. The interface is based on the Common User Access Advanced Interface Design Guide, which is part of the IBM Systems Application Architecture Library, and The Windows Interface: An Application Design Guide, which is part of the SDK. A memory handling technique is proposed to break the imposed 64 KB data segmentation. Connected finite element calculation routines are written in Fortran and compiled by the Salford FTN77/x86 32‐bit compiler. The protected mode interface of the Fortran compiler allows direct access by the GUI, and allows the computation to run as a 32‐bit background application, without memory limitations, in the multitasking environment. Finite element routines are supported by pre‐ and post‐processors comprising mesh generation, post‐processing for derived results, and graphical displays. A convenient contouring algorithm is proposed to generate contoured plots of nodal quantities in the form of iso‐lines or iso‐fields.

This study aims to introduce a new method for locating candidate substrates in part models and evaluating their feasibility.

Slices of an STL model along candidate directions are evaluated for the fitting of regular cylindrical and rectangular stock. Next, the part model is skeletonized and tested for collision assuming deposition growth of features from the candidate substrate.

The method is successfully able to find feasible substrates and conduct collision simulation for a variety of part models.

The algorithm is limited to cylindrical and rectangular substrates and only considers collision between the substrate and the deposition head.

This method represents a new approach to solving a portion of the hybrid manufacturing process planning problem.

The purpose of this paper is to investigate the combination of selective laser melting (SLM) and 5-axis CNC milling to produce parts from titanium powder. The aim is to achieve a more resource-efficient manufacturing process by reducing material wastage and machining time, while adhering to quality requirements.

A benchmark titanium aerospace component is manufactured with two different approaches using subtractive and additive manufacturing technologies. The first component is produced from a solid billet using only 5-axis CNC milling. The second component is grown from powder using SLM to produce a net-shaped part of which the final shape and part accuracy are achieved through 5-axis CNC milling. The potential saving of material and machining time of the process combination is evaluated by comparing it to the conventional purely CNC approach. The form accuracy, surface finish, mechanical properties and tool wear for the two processes are also compared.

The results show that the process combination can be used to produce Ti components that adhere to aerospace standards. With the process combination, a material saving of 87 per cent was achieved along with a reduction of 21 per cent in machining time. Further improvements are possible using optimized SLM build and machining strategies.

This paper presents the results of a resource efficiency assessment on the combination of SLM and 5-axis CNC milling for the titanium alloy, Ti6Al4V. It is expected that this process combination can make a significant contribution towards reducing material wastage and machining time for aerospace applications.

To remanufacture a disused part, a hybrid process needs to be taken in part production. Therefore, a reasonable machining route is necessary to be developed for the hybrid process. This paper aims to develop a novel process planning algorithm for additive and subtractive manufacturing (ASM) system to achieve this purpose.

First, a skeleton of the model is generated by using thinning algorithm. Then, the skeleton tree is constructed based on topological structure and shape feature. Further, a feature matching algorithm is developed for recognizing the different features between the initial model and the final model based on the skeleton tree. Finally, a reasonable hybrid machining route of the ASM system is generated in consideration of the machining method of each different sub-feature.

This paper proposes a hybrid process planning algorithm for the ASM system. Further, it generates new process planning insights on the hybrid process service provider market.

The proposed process planning algorithm enables engineers to obtain a proper hybrid machining route before product fabrication. And thereby, it extends the machining capability of the hybrid process to manufacture some parts accurately and efficiently.

This study addresses one gap in the hybrid process literature. It develops the first hybrid process planning strategy for remanufacturing of disused parts based on skeleton tree matching, which generates a more proper hybrid machining route than the currently available hybrid strategy studies. Also, this study provides technical support for the ASM system to repair damaged parts.

This paper aims to present a survey concerning the accuracy of thermoplastic polymeric parts fabricated by additive manufacturing (AM). Based on the scientific literature, the aim is to provide an updated map of trends and gaps in this relevant research field. Several technologies and investigation methods are examined, thus giving an overview and analysis of the growing body of research.

Permutations of keywords, which concern materials, technologies and the accuracy of thermoplastic polymeric parts fabricated by AM, are used for a systematic search in peer-review databases. The selected articles are screened and ranked to identify those that are more relevant. A bibliometric analysis is performed based on investigated materials and applied technologies of published papers. Finally, each paper is categorised and discussed by considering the implemented research methods.

The interest in the accuracy of additively manufactured thermoplastics is increasing. The principal sources of inaccuracies are those shrinkages occurring during part solidification. The analysis of the research methods shows a predominance of empirical approaches. Due to the experimental context, those achievements have consequently limited applicability. Analytical and numerical models, which generally require huge computational costs when applied to complex products, are also numerous and are investigated in detail. Several articles deal with artificial intelligence tools and are gaining more and more attention.

The cross-technology survey on the accuracy issue highlights the common critical aspects of thermoplastics transformed by AM. An updated map of the recent research literature is achieved. The analysis shows the advantages and limitations of different research methods in this field, providing an overview of research trends and gaps.

Two-photon polymerization (TPP) has become one of the most popular techniques for stereolithography at very high resolutions. When printing relatively large structures at high resolutions, one of the main limiting factors is the printing time. The purpose of this paper is to present a new slicing algorithm to minimize printing times.

Typically, slicing algorithms used for TPP do not take into account the fact that TPP can print at a range of resolutions (i.e. with different heights and diameters) by varying parameters such as exposure time, laser power, photoresist properties and optical arrangements. This work presents multiresolution layered manufacturing (MLM), a novel slicing algorithm that processes 3D structures to separate parts manufacturable at low resolution from those that require a higher resolution.

MLM can significantly reduce the printing time of 3D structures at high resolutions. The maximum theoretical speed-up depends on the range of printing resolutions, but the effective speed-up also depends on the geometry of each 3D structure.

MLM opens the possibility to significantly decrease printing times, potentially opening the use of TPP to new applications in many disciplines such as microfluidics, metamaterial research or wettability.

There are many instances of previous research on printing at several resolutions. However, in most cases, the toolpaths have to be manually arranged. In some cases, previous research also automates the generation of toolpaths, but they are limited in various ways. MLM is the first algorithm to comprehensively solve this problem for a wide range of true 3D structures.

This study aims to discuss the state-of-the-art digital factory (DF) development combining digital twins (DTs), sensing devices, laser additive manufacturing (LAM) and subtractive manufacturing (SM) processes. The current shortcomings and outlook of the DF also have been highlighted. A DF is a state-of-the-art manufacturing facility that uses innovative technologies, including automation, artificial intelligence (AI), the Internet of Things, additive manufacturing (AM), SM, hybrid manufacturing (HM), sensors for real-time feedback and control, and a DT, to streamline and improve manufacturing operations.

This study presents a novel perspective on DF development using laser-based AM, SM, sensors and DTs. Recent developments in laser-based AM, SM, sensors and DTs have been compiled. This study has been developed using systematic reviews and meta-analyses (PRISMA) guidelines, discussing literature on the DTs for laser-based AM, particularly laser powder bed fusion and direct energy deposition, in-situ monitoring and control equipment, SM and HM. The principal goal of this study is to highlight the aspects of DF and its development using existing techniques.

A comprehensive literature review finds a substantial lack of complete techniques that incorporate cyber-physical systems, advanced data analytics, AI, standardized interoperability, human–machine cooperation and scalable adaptability. The suggested DF effectively fills this void by integrating cyber-physical system components, including DT, AM, SM and sensors into the manufacturing process. Using sophisticated data analytics and AI algorithms, the DF facilitates real-time data analysis, predictive maintenance, quality control and optimal resource allocation. In addition, the suggested DF ensures interoperability between diverse devices and systems by emphasizing standardized communication protocols and interfaces. The modular and adaptable architecture of the DF enables scalability and adaptation, allowing for rapid reaction to market conditions.

Based on the need of DF, this review presents a comprehensive approach to DF development using DTs, sensing devices, LAM and SM processes and provides current progress in this domain.

This study aims to review Luhmann's theory of moral communication while focusing on symmetry conditions, in light of Armin Nassehi's criticism, to clarify issues regarding this concept. Then, Luhmann's symmetry condition is reconstructed as a concept containing double meaning via a case study in Japan. Correspondingly, interesting situations and characteristics of moral communication, such as “inflation,” the “polemogene” and ubiquity of moral communication, are interpreted more consistently.

In today's society, moral communication may spiral out of control and even be fatal. By examining Niklas Luhmann's theory, in this paper, the author elaborates on why and how this mechanism occurs.

The author emphasizes that the suspicion pertaining to the asymmetry of communication is stressed in the case of anonymity. When an individual communicates using a moral code, it is impossible to discern whether the implications of self-bindingness are undermined or not through observations or consequences of communication and can only be questioned or confirmed through communication. However, criticizing the outburst of the masses and exchanging blame by isolating only one aspect of such a phenomenon will only be superficial.

This study reveals that the very condition that makes moral communication possible enables people to communicate respectfully or contemptuously with others without any special qualification. Such an analysis can serve as a theoretical underpinning for the analysis of today's phenomena.