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In this paper a novel numerical methodology for calculating non-uniform residual stress distributions during the glass tempering process is presented. Tempering techniques lead to non-uniform heat transfer rates causing residual stress inhomogeneities, which consequently have a direct impact on the structural behaviour of components. Nevertheless, most works in the literature do not consider the influence of local flow phenomena during thermal calculations, resulting in non-representative residual stress distributions. In this context, a novel generalised methodology based on a fluid–structure interaction one-way approach to sequentially couple the thermal and mechanical fields is presented. In this way, the unsteady and non-uniform heat transfer rate is coupled with the Narayanaswamy model to predict the non-homogeneous residual stress pattern. The obtained numerical results for the analysed impinging jet array case are in good agreement both quantitatively and qualitatively, exhibiting an average error below 10% with respect to previous experimental investigations. Finally, efforts are made to reduce the computational time. Therefore, the proposed methodology proves to be an efficient tool for understanding the underlying mechanisms and predicting the residual stress distributions during glass tempering.

Large-scale experimental programmes become unavoidable to characterise the fracture behaviour of glass. Additionally, if non-uniform residual stresses are to be considered, the total effort required increases significantly. In this work, the primary failure cumulative distribution function (PFCDF) is derived from experimental annealed glass data. In this way, a novel methodology based on the characterisation of annealed glass to assess the failure of pre-stressed glass components is presented. Similarly, a joint evaluation of annealed and tempered glass is performed, thereby ensuring a higher reliability in the derivation of the PFCDF, which results in an average error below 10%.

Valves are mechanical devices for controlling fluid-flow in pipes of different diameter and service pressures used in several industry sectors. Most demanding industry sectors add custom design requirements and require product validation reports many times even before placing valve purchase orders of varying quantities. Therefore, customer and valve developer requirements must be made compatible, design reliably completed and a design validation report created, all as soon as possible. In order to respond to these market constraints, complete valve design process from product planning to product design and validation delivery must be optimized. This paper reports a 96% time reduction in Simulation Based Design validation and reporting tasks obtained by applying Design Automation in a company that develops valves for this market. Additionally, the architecture and most remarkable features of the Simulation Based Design validation and reporting automation are described.

Butterfly valves are widely used industrial piping components as on-off and flow controlling devices. The main challenge in the design process of this type of valves is the correct dimensioning to ensure proper mechanical performance as well as to minimise flow losses that affect the efficiency of the system. Butterfly valves are typically dimensioned in a closed position based on mechanical approaches considering uniform hydrostatic pressure, whereas the flow losses are analysed by means of CFD simulations. The main limitation of these approaches is that they do not consider either the influence of the dynamics of the manoeuvring stage or coupled phenomena. Recent works have included the influence of the flow on the mechanical behaviour for different opening angles by means of one-way FSI approach. However, these works consider steady-state flow for the selected angles, not capturing the effect of the transient flow evolution during the manoeuvring stage. Two-way FSI modelling approach could allow overcoming such limitations providing more accurate results. Nevertheless, the use of this technique is limited due to the increase in the computational cost. In the present work, the applicability of FSI one-way and two-way approaches is evaluated for the analysis of butterfly valves, showing that not considering fluid-structure coupling involves not capturing the most critical situation for the valve disc.

Temperature measurement in metal cutting is of central importance as tool wear and surface integrity have been demonstrated to be temperature dependent. In this context, infrared thermography is presented as a reliable technique to determine tool temperatures and thermal fields at near real-time. However, a constraint of this technique is that temperatures are measured on the tool side faces normal to the cutting edge but offset from the tool/chip contact. In the present research, tool/chip contact temperatures were calculated from the tool side based on analytical theories of heating and the principles of heat generation in cutting processes. The required inputs were commonly measurable variables (cutting and feed forces, chip thickness and tool/chip contact length). The proposed approach was combined with a new calibration method in which a calibration curve that directly relates real and radiated temperatures is obtained, instead of measuring the emissivity of the radiating surface. As a case study, the research was conducted on a set of four ferrite-pearlite steels (16MnCr5, 27MnCr, C45 and C60). The results demonstrated the effectiveness of the method to establish the real influence of the cutting conditions (cutting speed and feed) and to distinguish the effect that different work material microstructures have in tool/chip temperature. Furthermore, the results showed a high degree of accuracy and less than 12% deviation from the trends when compared with 2D cutting simulations.

In casting parts, due to the manufacturing process, the presence of defects such as porosity, inclusions and oxide films is unavoidable. All these irregularities have a negative effect on the component performance. Several works have demonstrated that, among them, porosity is especially detrimental to the fatigue properties. As most fatigue failures nucleate at the surface of a material, casting defects at or near the surface and surface roughness become an extremely important factor in determining the fatigue strength of cast components.Very little research has been conducted into the influence of both surface quality and porosity on the fatigue behaviour of aluminium castings parts. In the present work, the effects of two different surface qualities (machined and as-cast) on fatigue behaviour of an A356 casting alloy were studied. The S-N curves obtained showed that the cast surface had higher fatigue strength than the machined one. The failure in cast specimens initiated predominantly from valleys of the rough surface near pores or inclusions. On the other hand, in machined surfaces, the cracks initiated directly from surface pores. Thus, the improvement in fatigue life was attributed to a longer crack “initiation” period.

The protection of the viral genome during extracellular transport is an absolute requirement for virus survival and replication. In addition to the almost universal proteinaceous capsids, certain viruses add a membrane layer that encloses their double-stranded (ds) DNA genome within the protein shell. Using the membrane-containing enterobacterial virus PRD1 as a prototype, and a combination of nanoindentation assays by atomic force microscopy and finite element modelling, we show that PRD1 provides a greater stability against mechanical stress than that achieved by the majority of dsDNA icosahedral viruses that lack a membrane. We propose that the combination of a stiff and brittle proteinaceous shell coupled with a soft and compliant membrane vesicle yields a tough composite nanomaterial well-suited to protect the viral DNA during extracellular transport.

Residual Stress (RS) pattern changes considerably depending on the width of the plates and the welding parameters, having effect on the fatigue strength. Most of the standards do not consider them and in some works, yield stress is taken as residual stressvalue. It results in a very conservative estimation of fatigue life. Authors developed recently a numerical model to predict more properly the value of RS pattern depending on the plate thickness. In a welded joint, considering the RS and alternating axial loads, the evolution of the stresses is multiaxial, becoming necessary its study. Therefore, the aim of this work is to analyse different fatigue indicator parameters (Smith-Watson-Topper, Fatemi-Socie, and Critical Plane implementation of the Basquin equation) in order to predict the fatigue behaviour of butt-weld components. For that purpose, the numerical model to predict the RS pattern in welded joint developed by this research group is used.

A coupled Eulerian-Lagrangian Finite Element model of the orthogonal cutting process was developed to predict the influence that ferritepearlite steel variants have on fundamental process variables and tool wear. As a case study, this paper is focused on two different ferritepearlite inclusion free alloys, where mainly the influence of ferrite-pearlite ratio was tested. Flow stress behavior based on dynamic compression tests and thermal properties function of temperature were characterized for model input parameters. The numerical model is compared with orthogonal cutting tests where the cutting and feed forces, tool temperature, chip morphology and tool wear related variables were measured. Globally, predicted tendencies match with experiments in forces and temperatures. Widest differences on predictions were found for chip thickness and tool-chip contact length. Predicted wear rates are in accordance to experimentally measured values.

Gas metal arc welding (GMAW) is one of the most used joining method in the industry. However, one of the main problems of this process is the generation of residual stresses which have direct impact on the fatigue life of welded components. Nevertheless, residual stress pattern prediction is complex and requires the simulation of the welding process. Currently, there are different numerical methods to predict the residual stresses generated in GMAW process, being Goldak’s method one of the most widely used model. However, the main limitation of these methods is that they require defining many parameters experimentally and, consequently, this method is not valid during design process. Alternatively, in this work, it is developed a procedure where the heat source is defined based on the welding physics for spray transfer welding. The developed procedure has been validated for a spray transfer multipass butt weld case. Results have shown good correspondence with an average deviation of 9.16 % in thermal field and 42 MPa in the final residual stress field. Thus, the developed procedure has been validated as a cost-effective alternative method to estimate residual stress pattern in spray transfer multipass welding. Furthermore, the developed method does not require any welding experimental characterization once the efficiency of the used welding machine is defined. The proposed method can be used as a valid tool to optimize the welding process in order to minimize the residual stress field and, consequently, improve the fatigue life.

Tensile residual stresses are very often generated on the surface when machining nickel alloys. In order to determine their influence on the final mechanical behaviour of the component residual stress stability should be considered. In the present work the evolution of residual stresses induced by machining in Inconel 718 under static loading at room temperature has been studied. An Inconel 718 disc has been face turned and specimens for tensile tests have been extracted from the disc. Then surface residual stresses have been measured by X-ray diffraction for initial state and different loading levels. Finally, a finite element model has been fitted to experimental results and the study has been extended for more loading conditions. For the studied case, it has been observed that tensile residual stresses remain stable when applying elastic loads but they increase at higher loads close to the yield stress of the material.

Nusselt number correlation equations are numerically derived by characterizing the heat transfer phenomena through porous medium of both stacked and wound woven wire matrices of a Stirling engine regenerator over a specified range of Reynolds number, diameter and porosity. A finite volume method (FVM) based numerical approach is proposed and validated against well known experimentally obtained empirical correlations for a random stacking woven wire matrix, the most widely used due to fabrication issues, for Reynolds number up to 400. The results show that the numerically derived correlation equation corresponds well with the experimentally obtained correlations with less than 6% deviation with the exception of low Reynolds numbers. Once the numerical approach is validated, the study is further extended to characterize the heat transfer in a wound woven wire matrix model for a diameter range from 0.08 to 0.11 mm and a porosity range from 0.60 to 0.68 within the same Reynolds number range. Thus, the new correlation equations are numerically derived for different flow configurations of the Stirling engine regenerator. It is believed that the developed correlations can be applied with confidence as a cost effective solution to characterize and hence to optimize stacked and wound woven wire Stirling regenerator in the above specified ranges.

Friction pressure drop correlation equations are derived from a numerical study by characterizing the pressure drop phenomena through porous medium of both types namely stacked and wound woven wire matrices of a Stirling engine regenerator over a specified range of Reynolds number, diameter and porosity. First, a finite volume method (FVM) based numerical approach is used and validated against well known experimentally obtained empirical correlations for a misaligned stacked woven wire matrix, the most widely used due to fabrication issues, for Reynolds number up to 400. The friction pressure drop correlation equation derived from the numerical results corresponds well with the experimentally obtained correlations with less than 5% deviation. Once the numerical approach is validated, the study is further extended to characterize the pressure drop phenomena in a wound woven wire matrix model of a Stirling engine regenerator for a diameter range from 0.080 to 0.110 mm and a porosity range from 0.472 to 0.638 within the same Reynolds number range. Thus, the new correlation equations are derived from this numerical study for different flow configurations of the Stirling engine regenerator. The results indicate flow nature and complex geometry dependent friction pressure drop characteristics within the present Stirling engine regenerator system. It is believed that the developed correlations can be applied with confidence as a cost effective solution to characterize and hence to optimize stacked and woven Stirling engine efficiency in the above specified ranges.

Residual stress profiles induced by different dry face turning conditions are compared employing X-ray diffraction method, Hole-Drilling method and Finite Element Modelling. It is well known that the surface integrity condition has a great influence on the machined parts fatigue life, specially the residual stress profile. This issue is important when machining aeronautical critical parts, even more due to the difficulty of machining of nickel based superalloys, such as Inconel 718. This research work is focused on the identification of the residual stress profile uncertainty of experimental and numerical measurements. For this proposal, several measurements were carried out on a set of Inconel 718 samples machined with different conditions of cutting speed and feed rate under dry conditions. Although residual stress profiles are similar, differences are found between the three measurement techniques used in this study.

Due to the evolution of the last decades actual society is not focused exclusively in production anymore and people, safety and the environment preservation have become necessary issues in any aspect of the everyday living. Thus, worldwide governments are taking actions and have adopted new rules regarding those aspects, being remarkable the efforts to minimise the gas emissions responsible of global warming. As a consequence, new rules have direct repercussion in automotive and aerospace industries where weigh reduction has become one of the main goals to reduce vehicle fuel consumption and consequently minimise CO2 emissions. Thus, Magnesium alloys present high potential for automotive applications due to their lower density in comparison with other widely used structural materials. This property allows not only reducing vehicle weight but also improving dent resistance and shell resistance behaviour by increasing thickness in structural sheet applications. However, even magnesium alloys are already used to manufacture autoparts by die casting processes, some limitations, reported by many researchers, emerge when forming magnesium sheet parts. It is well known that due to their hexagonal close-packed (HCP) microstructure, magnesium alloys present low formability at room temperature. Although this property can be improved by increasing the forming temperature, this is not always achievable in conventional manufacturing processes. Consequently, the development of innovative forming processes, such as warm tube hydroforming (WTHF), is needed to extend the use of magnesium alloys in automotive and aerospace industry. WTHF processes allow combining the benefit of increasing forming temperature to overcome formability limitations in magnesium alloys with the widely known advantages that conventional Tube Hydroforming (THF) processes offer, such as the possibility to obtain complex hollow shapes, minimise the need of welding or simplify the assembly of components. In the, Gaur egungo gizarteak atzean utzi du ekoizpen soilean oinarritu zen garai hura gizartearekiko eta ingurumenarekiko kontzientzia garatuz. Eboluzio hori mundu-mailan gobernuek hartu dituzten neurri eta arauetan islatzen da eta bereziki negutegi efektuan eragin zuzena duten gasen emisio murrizketarako neurrietan. Guzti honek eragin zuzena du teknologikoki aurrerakoi diren automozio eta hegazkingintza sektoreetan, non pisu murrizketa ezinbesteko helburu bilakatu den erregai kontsumoa murrizteko eta ondorioz CO2 emisioak. Magnesio aleazioak oso aproposak dira sektore mota hauetan erabiltzeko oso dentsitate baxua baitute osagai estrukturaletan erabili ohi diren materialekin alderatuz. Propietate honek material honekin ekoiztutako pieza eta osagaien pisua murrizten laguntzeaz gain indentaziorako erresistentzia edo zurruntasun laminarra hobetzen laguntzen du lodiera handiagoak erabiltzea baimenduz. Halere, magnesio aleazioak injekzioko piezetan erabiltzen dira batik bat, izan ere ingurune tenperaturan duten konformagarritasun baxuak xafla konformaketa prozesuetarako erabilgarritasuna mugatzen baitu. Mundu-mailan egindako ikerketek erakutsi dute ingurune baldintza kontrolatuan konformaketa tenperatura igoaz magnesio aleazioen konformagarritasuna asko hobetu daitekeela, naiz eta baldintza horiek prozesu konbentzionaletan erreproduzitzea ez den hain samurra. Honen ondorioz, ezinbestekoa da konformaketa prozesu berritzaileak garatzea muga hauek gainditu ahal izateko. Tutu hidrokonformaketa beroan (aurrerantzean WTHF) teknologia berritzaile hauetariko bat da non magnesio aleazioak konformatzeko baldintza aproposak tutu hidrokonformaketa prozesu konbentzionalek (THF) eskaintzen duten abantailekin konbinatzen diren. Prozesu mota hauen abantaila nagusienetarikoak dira lodiera estuko pieza itxi konplexuak konformatzeko gaitasuna, lotura soldatuen beharra murriztea eta osagaien muntaia erraztea besteak beste. Tesi honetan garatu den ikerkuntzan xafla konformaketa prozesuetan gehien e, En la actualidad nos encontramos ante una sociedad que ha dejado atrás una época industrial centrada meramente en la producción y ha desarrollado una conciencia social y de protección del medio ambiente. Ello se refleja en las nuevas medidas y normativas que los gobiernos de las diferentes naciones han adoptado y que hacen especial hincapié en la reducción de la emisión de gases responsables del efecto invernadero. Todo ello, repercute de forma directa en sectores tecnológicamente punteros como son la automoción y la aeronáutica, donde la reducción de peso se ha convertido en un objetivo fundamental de cara a la reducción de consumo de combustible y como consecuencia la reducción de emisiones de CO2. Las aleaciones de magnesio presentan un elevado potencial para su aplicación en este tipo de sectores ya que presentan una baja densidad en comparación con los materiales más empleados en componentes estructurales. Esta propiedades no solo permite reducir el peso de los componentes fabricados en este material, sino que como consecuencia del empleo de espesores mayores se mejoran propiedades como la resistencia a la indentación y la rigidez laminar. No obstante, a pesar de que las aleaciones de magnesio ya se emplean para fabricar componentes inyectados, su uso en aplicaciones de chapa y tubo es todavía limitado debido a la baja conformabilidad que presentan a temperatura ambiente. A pesar de ello, estudios llevados a cabo bajo condiciones controladas han demostrado que el incremento de la temperatura de conformado permite aumentar dicha propiedad, aunque trasladar dichas condiciones a los procesos de transformación de chapa convencionales puede resultar complicado. Como consecuencia, es necesario el desarrollo de tecnologías de conformado innovadoras que permitan hacer frente a dichas limitaciones. El hidroconformado de tubo en caliente (en adelante WTHF) es una de estas tecnologías y permite combinar las condiciones de conformado apropiadas para este tipo de aleaciones