Applicability testing of constructive computational mechanisms (CCMs) is a new challenge for both the academia and the industry. The overwhelming majority of the existing validation approaches focuses on the internal validity of CCMs (e.g. consistency, bias), while there is a shortage of efficient approaches for assessing the external validity (e.g. applicability, reusability). The objective of this paper is to clarify the concepts and criteria, and to develop an approach for a systematic evaluation of the applicability of a given CCM to cases that were not considered at design time. The approach is adapted from the validation square approach (VSA). The adapted methodology (A-VSA) makes it possible to evaluate CCMs from (a) theoretical structural, (b) empirical structural, (c) theoretical performance, and (d) empirical performance dimensions. Altogether eight indicators are introduced that support the evaluation process. The effectiveness of the A-VSA was confirmed through a case study, in which a specific CCM is considered and the strategy of the A-VSA was operationalized with three completely different application cases. As evidenced by the results, the proposed A-VSA establishes a tight coupling among the enablers embraced by a CCM and the aspects of theoretical and empirical validation, which approves the approach to be an efficient tool for defining the range and/or the extent of applicability. The advantage of the A-VSA is that it offers a way to transfer qualitative applicability evaluation into quantitative applicability assessment, which allows the use of both subjective statements and mathematical modeling in applicability testing. The results of the assessment can guide the adaptation work of a CCM when applied to an out-of-domain application.@en

The deposition process of wire and arc additive manufacturing (WAAM) is usually planned based on a bead geometry model (BGM), which represents the relationship between bead geometries (e.g. width, height) and required deposition parameters. However, the actual deposition situation may deviate from the one in which the BGM is built, such as varied heat dissipation conditions, resulting in morphological changes of deposited beads and geometrical errors in the formed parts. In this paper, a novel control mechanism for enhancing the fabrication accuracy of WAAM based on fuzzy-logic inference is proposed. It considers the geometrical errors measured on already deposited layers and deposition context to adjust deposition parameters of beads in the subsequent layer, forming an interlayer closed-loop control (ICLC) mechanism. This paper not only presents the theoretical fundamentals of the ICLC mechanism but also reports the technical details about utilizing this mechanism to control the forming height of multi-layer multi-bead (MLMB) components. A fuzzy-logic inference machine was applied as the core component for calculating speed change of bead deposition based on height error and previously applied change. In terms of validation, the effectiveness of the proposed control mechanism and the implemented controller was investigated through both simulative studies and real-life experiments. The fabricated cuboid blocks showed good accuracy in height with a maximum error of 0.20 mm. The experimental results implied that the proposed ICLC approach facilitates deposition continuity of WAAM, and thus enables process automation for robotic manufacturing.

A greedy heuristic-based algorithm was put forward to obtain the approximate optimal solution for the DUDC(discrete unit disk cover) problem within polynomial time. Firstly, discrete cells were generated to represent the 2D plane. Then, alternative sets which can cover certain amount of target points were built. A greedy algorithm was articulated to find a minimal combination of the alternative sets, and full coverage of all target points was realized. The minimal covering circles were calculated considering the position of each point in the sets. The center of the minimal covering circles was selected as the location. Based on a case study, the effectiveness of the proposed algorithm was validated. The factors of influence the performance of the algorithm were also discussed and ratio of time complexity and approximation was analyzed.@en

The deposition process of wire and arc additive manufacturing (WAAM) is usually planned based on a bead geometry model (BGM), which represents the relationship between bead geometries (e.g. width, height) and required deposition parameters. However, the actual deposition situation may deviate from the one in which the BGM is built, such as varied heat dissipation conditions, resulting in morphological changes of deposited beads and geometrical errors in the formed parts. In this paper, a novel control mechanism for enhancing the fabrication accuracy of WAAM based on fuzzy-logic inference is proposed. It considers the geometrical errors measured on already deposited layers and deposition context to adjust deposition parameters of beads in the subsequent layer, forming an interlayer closed-loop control (ICLC) mechanism. This paper not only presents the theoretical fundamentals of the ICLC mechanism but also reports the technical details about utilizing this mechanism to control the forming height of multi-layer multi-bead (MLMB) components. A fuzzy-logic inference machine was applied as the core component for calculating speed change of bead deposition based on height error and previously applied change. In terms of validation, the effectiveness of the proposed control mechanism and the implemented controller was investigated through both simulative studies and real-life experiments. The fabricated cuboid blocks showed good accuracy in height with a maximum error of 0.20 mm. The experimental results implied that the proposed ICLC approach facilitates deposition continuity of WAAM, and thus enables process automation for robotic manufacturing.@en

The deposition process of wire and arc additive manufacturing (WAAM) is usually planned based on a bead geometry model (BGM), which represents the relationship between bead geometries (e.g. width, height) and required deposition parameters. However, the actual deposition situation may deviate from the one in which the BGM is built, such as varied heat dissipation conditions, resulting in morphological changes of deposited beads and geometrical errors in the formed parts. In this paper, a novel control mechanism for enhancing the fabrication accuracy of WAAM based on fuzzy-logic inference is proposed. It considers the geometrical errors measured on already deposited layers and deposition context to adjust deposition parameters of beads in the subsequent layer, forming an interlayer closed-loop control (ICLC) mechanism. This paper not only presents the theoretical fundamentals of the ICLC mechanism but also reports the technical details about utilizing this mechanism to control the forming height of multi-layer multi-bead (MLMB) components. A fuzzy-logic inference machine was applied as the core component for calculating speed change of bead deposition based on height error and previously applied change. In terms of validation, the effectiveness of the proposed control mechanism and the implemented controller was investigated through both simulative studies and real-life experiments. The fabricated cuboid blocks showed good accuracy in height with a maximum error of 0.20 mm. The experimental results implied that the proposed ICLC approach facilitates deposition continuity of WAAM, and thus enables process automation for robotic manufacturing.@en