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This paper presents a novel numerical model, based on the finite element (FE) method, for the simulation of a welding process aimed to make a two‐pass V‐groove butt joint, paying attention on the prediction of residual stresses and distortions. The 'element birth and death' technique for the simulation of the weld filler supply has been considered within this paper. The main advancements with respect to the state of the art herein proposed concern: (i) the development of a modelling technique able to simulate the plates interaction during the welding operation when an only plate is modelled. This phenomenon is usually neglected in literature; (ii) the heat amount is supplied to the FEs as volumetric generation of the internal energy, allowing overcoming the time‐consuming calibration phase needed to use the Goldak's model, commonly adopted in literature. Predicted results showed a good agreement with experimental ones. [ABSTRACT FROM AUTHOR]

In this work laser‐welded tube‐tube specimens made of aluminium alloys AlMg3.5Mn and AlSi1MgMn T6 were experimentally tested under constant and variable amplitude loading, under pure axial and pure torsion loading. In order to evaluate the influence on fatigue behaviour of the residual stresses, because of the welding process, some specimens were subjected to postweld heat treatment and then were tested. The numerical analyses, using finite element (FE), were carried out to obtain a reliable estimation of the residual stress in the specimen. The numerical results were in a good agreement with experimental ones obtained by means of hole‐drilling method. Finally, the residual stress distribution was superimposed to stress distribution because of fatigue loads obtained by FE analyses applying local concept, to calculate the stresses in the crack initiation zone and to understand the different types of failure that occurred in as‐welded and relieved specimens. [ABSTRACT FROM AUTHOR]

This work deals with the investigation and characterization of Ti6Al4V parts produced with an intriguing manufacturing process belonging to the Wire Arc Additive Manufacturing (WAAM) family: the Cold Metal Transfer technology (CMT). Wall‐shaped parts were produced according to different process parameters, namely the wire feed speed and voltage–current combinations, leading to different energy inputs. The parts were characterized in terms of surface morphology, microhardness, microstructure, tensile properties, and fatigue crack growth. The results suggested that the investigated deposition parameters led to similar results. Moreover, the mechanical and fatigue crack growth behavior was in line with parts of the same alloy produced through other manufacturing routes, whereas the microstructure type was the result of the fast cooling of the molten material. Finally, considering the simple system adopted to avoid oxidation during the deposition stage, the results suggested that CMT is a promising manufacturing technique for titanium alloy semifinished parts. Highlights: Wall‐like parts made of Ti6Al4V alloy were produced through WAAM‐CMT technologySound parts with minimum oxidation were produced through a simple enveloping systemThe parts had properties similar to those of more traditional manufacturing routesThe microstructure, tensile, and fatigue crack growth behavior were quite isotropic [ABSTRACT FROM AUTHOR]

In the present work, a preliminary design of an eco‐sustainable bamboo electric treadmill bike is carried out. It is a new means of transport with zero environmental impact that also allows to overcome the main disadvantage of the indoor training. Bamboo, as an eco‐friendly material, has great potential as construction material for bike frames because it represents an alternative for more traditional materials such as steel, aluminum, and composite. A finite element model of the designed prototype is developed and then validated using Abaqus commercial code following the UNI EN 14764 static standard. Numerical analyses show good structural behavior of the designed frame in compliance with the regulations. [ABSTRACT FROM AUTHOR]

The recent improvement of additive manufacturing (AM) technologies has been attracting the industry and research community attention. This paper aims to investigate the influence of building position and printing scheme on the tensile mechanical properties of Tough polylactic acid (PLA) material, manufactured through a fused deposition modeling (FDM) 3D printing – the S5 ProBundle Ultimaker. FDM 3D printing, also known as fused filament fabrication (FFF), is an AM process within the realm of material extrusion. FDM builds parts Layer by Layer by selectively depositing melted material in a predetermined path, and uses thermoplastic polymers that come in the form of filaments. In this paper, AM Tough PLA specimens are manufactured according to ASTM‐D638 requirement considering two different positions on the building plate and two printing schemes. Specimens are tested under static tensile test and the mechanical properties are extracted. [ABSTRACT FROM AUTHOR]

Three‐dimensional numerical analyses, using the finite element method (FEM), have been adopted to simulate fatigue crack propagation in a hollow cylindrical specimen, under pure axial or combined axial‐torsion loading conditions. Specimens, made of Al alloys B95AT and D16T, have been experimentally tested under pure axial load and combined in‐phase constant amplitude axial and torsional loadings. The stress intensity factors (SIFs) have been calculated, according to the J‐integral approach, along the front of a part through crack, initiated in correspondence of the outer surface of a hollow cylindrical specimen. The crack path is evaluated by using the maximum energy release rate (MERR) criterion, whereas the Paris law is used to calculate crack growth rates. A numerical and experimental comparison of the results is presented, showing a good agreement in terms of crack growth rates and paths. [ABSTRACT FROM AUTHOR]