International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

In this paper, the inherent strain method is employed for the purpose of predicting welding residual stresses in large shell structures. Such structures include roof structures in the construction industry and deck sections in the shipbuilding industry. The study focuses on the numerical aspect of the inherent strain method, with the objective of investigating the most appropriate technique for transferring analytically calculated inherent strains into the elastic finite element model of the structure. The approach under consideration takes into account the thermally induced stresses, to the extent that they are considered to be significant for the structures and their behaviour in question, with the objective of determining the field of welding residual stresses over the entire structure (macro-scaled). The work proposes theoretical parameters for the alignment of finite element meshes within the weld seam domain. The discussion in the conclusion encompasses the general application capabilities, limitations, and challenges for further development

The Cyber-Physical System (CPS) is one of the main concepts associated to the Industry 4.0 framework. The paper aims at analyzing the futures and architecture and technologies of CPS, retracting it in form its general conceptualization, to the interpretation in high relevant problem of welding manufacturing in context of Industry 4.0. The most recent approaches are based on empirical models or AI and rely on experimental data collection. On the other hand, the actuator shell control a certain parameter or parameter set. Under close consideration of the state of the knowledge to the problem of out-of-plane welding distortions, the aspects related to data sensing and actuating process parameters are analysed. However, due to the intensive development of the welding techniques und machines as well as the increasing focus on lightweight design pose a challenge that enters an unstudied parameter domain. To address this problem, a study was carried out using a combination of experimental and numerical methods. Based on the obtained results, the existing analytical expressions are supplemented and put into discussion. Essential findings, as well as the correlations between the occurring out-of-plane distortions and the welding process conditions and parameters are emphasized. Thus, the level of knowledge and the range of application of the existing analytical models are extended. On this basis, the development of highly effective deterministic-driven CPS in the context of Industry 4.0 is advanced.

The article presents a comparison of different computational approaches used to study the surface treatment of a NiCrMoV steel with 0.55% Carbon content by a plasma jet. Metallographic observations show formation of martensite layer due to high cooling rate by heat transfer into the bulk steel. Heat affected zone (HAZ) was 1 mm deep and 10-12 mm wide. The treated surface maximum hardness was measured at 763 HV0.1 whereas untreated steel was at 210 HV 0.1. The computation indicates a hardening sink near the surface that went undetected in the experimental observations. The ability of the different computational approaches to explore the process related phenomena and to give reliable results is put into discussion.

An coupled analytic-numerical model for calculation of distortions arising by welding fabrication is introduced. Target of the analytical model is the calculation of the inherent strains after the local thermal-mechanical influence of the welding or thermal straightening process. Following the fabrication processing chart the strains are loaded on an elastic FE-model of the structure and the residual stresses and distortions of the whole structure are calculated. The consideration of welding and thermal straightening scenarios, inclusively the assembling stages, is done by taking into consideration the intermediate variation of the strain state in the FE-model of the structure at every processing step. The important physical relations are demonstrated. The model is intended to be used for solving industrial tasks, i.e. intending acceptable precision and calculation time as well as low simulation costs.

An coupled analytic-numerical model for calculation of distortions arising by welding fabrication is introduced. Target of the analytical model is the calculation of the inherent strains after the local thermal-mechanical influence of the welding or thermal straightening process. Following the fabrication processing chart the strains are loaded on an elastic FE-model of the structure and the residual stresses and distortions of the whole structure are calculated. The consideration of welding and thermal straightening scenarios, inclusively the assembling stages, is done by taking into consideration the intermediate variation of the strain state in the FE-model of the structure at every processing step. The important physical relations are demonstrated. The model is intended to be used for solving industrial tasks, i.e. intending acceptable precision and calculation time as well as low simulation costs.