Additive manufacturing (AM) or, more commonly, 3D printing is one of the fundamental elements of Industry 4.0. and the fourth industrial revolution. It has shown its potential example in the medical, ...automotive, aerospace, and spare part sectors. Personal manufacturing, complex and optimized parts, short series manufacturing and local on-demand manufacturing are some of the current benefits. Businesses based on AM have experienced double-digit growth in recent years. Accordingly, we have witnessed considerable efforts in developing processes and materials in terms of speed, costs, and availability. These open up new applications and business case possibilities all the time, which were not previously in existence. Most research has focused on material and AM process development or effort to utilize existing materials and processes for industrial applications. However, improving the understanding and simulation of materials and AM process and understanding the effect of different steps in the AM workflow can increase the performance even more. The best way of benefit of AM is to understand all the steps related to that—from the design and simulation to additive manufacturing and post-processing ending the actual application.The objective of this Special Issue was to provide a forum for researchers and practitioners to exchange their latest achievements and identify critical issues and challenges for future investigations on “Modeling, Simulation and Data Processing for Additive Manufacturing”. The Special Issue consists of 10 original full-length articles on the topic.
Despite much research and applications, glass material and its use in buildings is still challenging for engineers due to its inherent brittleness and characteristic features such as sensitivity to ...stress concentrations, reduction in strength over time and from temperature, and breakage due to the stresses that may build up because of thermal gradients. This paper presents the results of an original test series carried out on monolithic glass panes with the dimensions of 500 × 500 mm2 and different thicknesses, under the exposure to radiant heating. The research study also includes a one-dimensional (1D) heat transfer model and a numerical, three-dimensional (3D) thermo-mechanical model that are used to investigate in greater detail the phenomena observed during the experiments. As shown, the behaviour of glass under radiant heating is rather complex and confirms the high vulnerability of this material for building applications. The usability and potential of thermo-mechanical numerical models is discussed towards experimental feedback.
In the present study a finite element model of the FSW process is built and a FSW butt weld of two aluminium alloy 2024-T3 plates is simulated using a fully coupled thermo-mechanical analysis. ...Besides the welded panels, the model includes the backing plate and the welding tool as physical bodies, which makes the simulations more realistic. The model also includes conductive heat transfer between the contact surfaces of the FSW tool, the aluminium plates and the backing plates, heat generation due to friction between the tool and the welded plates and heat loss to the ambient air due to convection.The simulated model makes it possible to analyse and check several aspects of this welding technique. It is proved that tool geometry has a vital importance in the FSW process. The influence of using instantaneous or ramped velocity at the beginning of the simulations is also studied. Moreover, it is seen that the mesh used in the finite element analysis and the adjustment of the inelastic heat fraction have a great influence on the obtained results.
As an introduction to this thematic issue on “Modelling approaches in sedimentology”, this paper gives an overview of the workshop held in Paris on 7 November 2013 during the 14th Congress of the ...French Association of Sedimentologists. A synthesis of the workshop in terms of concepts, spatial and temporal scales, constraining data, and scientific challenges is first presented, then a discussion on the possibility of coupling different models, the industrial needs, and the new potential domains of research is exposed.
The Carpathians orogenic system, with its along-arc variations in topography developed in the aftermath of continental collision, is associated with unusual foredeep basins, large-scale strain and ...seismicity concentration and high-velocity mantle bodies. The East Carpathians continental collision was non-cylindrical, leading to large-scale variations in thrust nappe kinematics, orogenic uplift patterns and foredeep subsidence, controlled by the mechanics and geometry of the lower plate. Thermo-mechanical modelling demonstrates that in this low-rate convergence regime, the subducted lithosphere had enough time to interact with the mantle to advance towards a thermal resettlement. This is favored by the low degree of metamorphism, mechanical weakness of the lower plate and the lack of active surface processes at the contact with and in the upper plate. In contrast, low-buoyant, thick lower crust and active surface processes keep the continuity of the slab intact and promote the development of typical foredeep basins. The model explains in a self-consistent manner the unusual geometry of the Vrancea seismogenic slab in the bend zone of the Romanian Carpathians. The model is also consistent with the presence of two high-velocity bodies inferred from seismic tomography studies and explains the depth zonation of seismicity in the Vrancea area. Differences between the northern part of East Carpathians and the southeastern bend of the Carpathians arc are largely controlled by lateral variations in crustal structure, topography emplacement and surface processes along the arc. Mechanical heterogeneity of the Carpathians subduction leads to the development of two end member modes of collision, allowing a study of these states and their transition. Lithospheric configuration and tectonic topography appear to be prime factors controlling variations in slab behavior. In the SE Carpathians, at the terminal phase of continental convergence, slab delamination, roll-back and depocenter migration appear to play a more limited role at shallow and lithospheric levels.
Tensile tests on three high-strength steels exhibiting Lüders band propagation are carried out at room temperature and under quasi-static loading conditions. Displacement and temperature fields on ...the surface of the flat samples are measured by digital image correlation and digital infrared thermography, respectively. The true stress versus true strain curves were calculated from the displacement data, while the thermal data were used to estimate the heat sources using the local heat diffusion equation. Based on these measurements the stored and dissipated energies were estimated up to diffuse necking. A thermodynamically consistent elastic-plastic constitutive model including the von Mises yield criterion, the associated flow rule and two non-linear isotropic hardening variables is applied to describe the behaviour of the high-strength steels. It is shown that this simple model is able to reproduce both the local behaviour, such as the power associated to heat sources, and the global behaviour, such as Lüders band propagation and stored and dissipated energies. It is further shown that the ratio of dissipated power to plastic power varies during plastic straining and that this variation is captured reasonably well in the numerical simulations.
Irreversible solid–solid phase transformations can be observed on samples of some metallic materials subjected to repeated compression loads. These phenomena, which are also known as “Tribological ...Surface Transformations” (TSTs), have been affecting some of French railroad network’s rails for about twenty years. Although the exact mechanisms responsible for apparition of the TSTs are not well understood so far, they seem to develop when the mechanical loads are combined with thermal effects occurring in the wheel/rail contact areas. The two thermo-mechanical models developed in the present study are based on the assumption that the thermo-mechanical loads may generate solid–solid phase transformations during the rolling contact. 2-D finite element analysis is conducted in order to illustrate the ability of these models to describe TSTs initiation and development in the immediate vicinity where the mechanical loads are applied.
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•A flow diagram for the solution of thermo-mechanical FEA models is proposed.•The proposed flow diagram consists of three different phases.•It provides a step-by-step guide for the ...development of the model.•It deals with convergence issues, mesh density and time step magnitude estimation.•Practical guidelines are provided.
In this paper the authors propose a practical flow diagram for the systematic development and solution of complex thermo-mechanical finite element analysis models. The proposed diagram consists of three different phases and provides a step-by-step guide for the development of the final thermo-mechanical model, taking into account convergence issues, mesh density and estimation of time step magnitude. In phase I, a preliminary thermo-mechanical analysis is carried out in order to get an idea of the model behaviour, the required resources and the feasibility of the overall analysis. In phase II the final thermal model is developed in full, taking into account the mechanical results obtained at the end of phase I, whereas in phase III the final mechanical model is generated on the basis of a continuously modified thermal model. The proposed procedure presented herein in the form of a flow diagram provides the capability for gradual output of the numerical results (preliminary results, thermal results, mechanical results), while paying attention to the time-consuming problem of results convergence required for a numerically accurate analysis. The former is an important issue for large-scale complex simulation projects, whereas the latter provides evidence that the development of the numerical model has been realized on the basis of the modelling laws. For better presentation and understanding, the proposed procedure is applied to the study of a finite element analysis thermo-mechanical model, where increased intricacy generally exists.
A better understanding of heat partition between the tool and the chip is required in order to produce more realistic finite element (FE) models of machining processes. The objectives are to use ...these FE models to optimise the cutting process for longer tool life and better surface integrity. In this work, orthogonal cutting of AISI/SAE 4140 steel was performed with tungsten-based cemented carbide cutting inserts at cutting speeds ranging between 100 and 628 m/min with a feed rate of 0.1 mm/rev and a constant depth of cut of 2.5 mm. Cutting temperatures were measured experimentally using an infrared thermal imaging camera. Chip formation was simulated using a fully coupled thermo-mechanical finite element model. The results from cutting tests were used to validate the model in terms of deformed chip thickness and cutting forces. The coupled thermo-mechanical model was then utilised to evaluate the sensitivity of the model output to the specified value of heat partition. The results clearly show that over a wide range of cutting speeds, the accuracy of finite element model output such as chip morphology, tool–chip interface temperature, von Mises stresses and the tool–chip contact length are significantly dependent on the specified value of heat partition.
► Tribological Surface Transformations are quasi-surface solid–solid phase transformations. ► We model irreversible phase transformations in a thermo-mechanical framework. ► We exhibit conditions for ...the local equations to be thermodynamically consistent. ► Main lines of the numerical procedure for solving the structural problem are presented. ► Numerical reproductions of Tribological Surface Transformations are given and discussed.
Some of the French railroad network’s rails have been affected for the last about twenty years or so by an undesirable physical phenomenon known as Tribological Surface Transformations (TSTs), which are irreversible, quasi-surface solid–solid phase transformations. Although the physical causes of TSTs have not yet been clearly established, it seems likely that the mechanical loads combined with the thermal effects of the wheel/rail contacts may be largely responsible. The present study is based on the assumption that the combined thermo-mechanical constraints may generate solid–solid phase transformations. The thermo-mechanical model developed on these lines was based on previous studies on TRansformation Induced Plasticity (TRIP), which are extended here to account for TSTs. The ability of the model to describe TSTs initiation and development is also assessed by performing a 2-D finite element analysis.
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