One of the principal energy absorbing structural components that influences the crashworthiness of a vehicle is the side-rail, which is also commonly referred to as an s-rail due to its shape that is reminiscent of an “s”. To improve the crashworthiness of a vehicle, in the wake of significant environmental pressures requiring vehicle light-weighting, the parameters that govern the crash response of the s-rail and the implications of light-weight material substitution need to be better understood. In this work, the main parameters that govern the crash response of an s-rail and the variables that influence them were identified and assessed through a combined experimental and numerical modelling programme. In particular, the as-formed properties of aluminium alloy s-rails, due to the tube bending and hydroforming fabrication route were examined. Tube bending, hydroforming and crash experiments were conducted to examine and assess the effects of initial tube thickness, strength, geometry, bend severity, work hardening, thickness changes and residual stresses on the crash response of the s-rail. The forming process variables, springback, thickness, strains, and force and energy response measured in the experiments were used to validate the finite element models developed herein. The validated numerical models of tube bending, hydroforming and crash provided additional insight and also allowed further investigation of the parameters governing the crash response of s-rails. The relevant parameters governing the crash response of s-rails were isolated and the basis for a set of design guidelines, in terms of maximizing energy absorption or minimizing mass, was established. The overall size is the most influential design parameter affecting the energy absorption capability of the s-rail, followed by the initial thickness, material strength, cross-sectional geometry, bend severity and hydroforming process employed, and finally boost in bending. The most significant conclusion made based on this research is that the effects of forming history must be considered to accurately predict the crash response of the s-rail. There are additional conclusions with respect to the tube bending and hydroforming processes, as well as s-rail crash response, that will contribute to improving the design of s-rails for better crashworthiness of vehicles.

One of the principal energy absorbing structural components that influences the crashworthiness of a vehicle is the side-rail, which is also commonly referred to as an s-rail due to its shape that is reminiscent of an “s”. To improve the crashworthiness of a vehicle, in the wake of significant environmental pressures requiring vehicle light-weighting, the parameters that govern the crash response of the s-rail and the implications of light-weight material substitution need to be better understood. In this work, the main parameters that govern the crash response of an s-rail and the variables that influence them were identified and assessed through a combined experimental and numerical modelling programme. In particular, the as-formed properties of aluminium alloy s-rails, due to the tube bending and hydroforming fabrication route were examined. Tube bending, hydroforming and crash experiments were conducted to examine and assess the effects of initial tube thickness, strength, geometry, bend severity, work hardening, thickness changes and residual stresses on the crash response of the s-rail. The forming process variables, springback, thickness, strains, and force and energy response measured in the experiments were used to validate the finite element models developed herein. The validated numerical models of tube bending, hydroforming and crash provided additional insight and also allowed further investigation of the parameters governing the crash response of s-rails. The relevant parameters governing the crash response of s-rails were isolated and the basis for a set of design guidelines, in terms of maximizing energy absorption or minimizing mass, was established. The overall size is the most influential design parameter affecting the energy absorption capability of the s-rail, followed by the initial thickness, material strength, cross-sectional geometry, bend severity and hydroforming process employed, and finally boost in bending. The most significant conclusion made based on this research is that the effects of forming history must be considered to accurately predict the crash response of the s-rail. There are additional conclusions with respect to the tube bending and hydroforming processes, as well as s-rail crash response, that will contribute to improving the design of s-rails for better crashworthiness of vehicles.

Le procédé d'hydroformage est largement utilisé dans les industries automobile et aéronautique. L'optimisation déterministe a été utilisée pour le contrôle et l'optimisation du procédé durant la dernière décennie. Cependant,dans des conditions réelles, différents paramètres comme les propriétés matériaux,les dimensions géométriques, et les chargements présentent des aléas qui peuvent affecter la stabilité et la fiabilité du procédé. Il est nécessaire d'introduire ces incertitudes dans les paramètres et de considérer leur variabilité. L'objectif principal de cette contribution est l'évaluation de la fiabilité et l'optimisation du procédé d'hydroformage en présence d'incertitudes.La première partie de cette thèse consiste à proposer une approche générale pour évaluer la probabilité de défaillance spatiale du procédé d'hydroformage, principalement dans les régions critiques. Avec cette approche, il est possible d'éviter les instabilités plastiques durant une opération d'hydroformage. Cette méthode est basée sur des simulations de Monte Carlo couplée avec des métamodèles. La courbe limite de formage est utilisée comme critère de défaillance pour les instabilités plastiques potentielles.La seconde partie de cette thèse est l'optimisation avec prise en compte d'incertitudes dans le procédé d'hydroformage. En utilisant des exemples illustratifs, on montre que l'approche probabiliste est une méthode efficace pour l'optimisation du procédé pour diminuer la probabilité de défaillance et laisser le procédé insensible ou peu sensible aux sources d'incertitudes. La difficulté est liée à la considération des contraintes fiabilistes qui nécessitent d'énormes efforts de calcul et impliquent des problèmes numériques classiques comme la convergence, la précision et la stabilité. Pour contourner ce problème, la méthode de surface de réponse couplée à des simulations Monte Carlo est utilisée pour évaluer les contraintes probabilistes.L'approche probabiliste peut assurer la stabilité et la fiabilité du procédé et minimise considérablement le pourcentage des pièces défectueuses. Dans cette partie, deux méthodes sont utilisées : l'optimisation fiabiliste et l'optimisation robuste.La dernière partie consiste à optimiser le procédé avec une stratégie Multi-Objectif(MO) avec prise en compte d'incertitudes. Le procédé d'hydroformage est un problème MO qui consiste à optimiser plus d'une performance simultanément.L'objectif principal est d'étudier l'évolution du front de Pareto lorsque des incertitudes affectent les fonctions objectifs ou les paramètres. Dans cette partie, on propose une nouvelle méthodologie qui présente les solutions dans un nouvel espace et les classifie suivant leurs probabilités de défaillances. Cette classification permet d'identifier la meilleure solution et fournit une idée sur la fiabilité de chaque solution. / Hydroforming process is widely used in automotive and aerospace industries. Deterministic design optimization have been used to control and optimize this process in the last decade. However, under realistic conditions, different parameters such as material properties, geometric dimensions, and load exhibits unavoidable scatter that can affect the stability and the reliability of the process.It is interesting to introduce the uncertainties in parameter and to consider their variability. The main objective of this contribution is to evaluate the reliability and optimization of the hydroforming process in the presence of uncertainties.The first part of this thesis proposes a general approach to evaluate the spatial probability of failure in hydroforming process mainly in the critical region. With the proposed approach it is possible to avoid failure during hydroforming process.This method is based on Monte Carlo simulation coupled with metamodels, the forming limit curve is used as failure criteria for potential plastic instabilities.The second part of this thesis is the optimisation of the hydroforming process under uncertainties. Using illustrative examples, it is shown that probabilistic approach is an efficient method to optimize the process, to decrease the probability of failure and make the process insensitive or less sensitive to sources of variability. The difficulty lies in the considerations of the reliability constraints, which require a large computational effort and involve classical numerical problems, such as convergence,accuracy and stability. To overcome this problem, response surface method with Monte Carlo simulations were used to evaluate the probabilistic constraints.Probabilistic approach can ensure a stable and reliable process and decrease the percentage of defects parts significantly. Through this part, two methods were used : Reliability-Based Design Optimization and robust optimization.The last part consists of optimizing the process with Multi-Objective (MO) strategy taking account of the uncertainty. Metal forming process is MO problem that consists of optimizing more than one performance simultaneously. The main goal isto study the evolution of the Pareto front when some uncertainties can affect the objective functions or the parameters. In this part, a new methodology is proposed which presents the solutions in a new space and classify the whole solution with their probability of failure. This classification allows to identify the best solutionand can provide an idea about the reliability of each solution.

Orientador: Sergio Tonini Button / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-07T01:24:29Z (GMT). No. of bitstreams: 1 Caldin_Renato_M.pdf: 3510420 bytes, checksum: 7632c444a9b61c552c640c1faec863a9 (MD5) Previous issue date: 2006 / Resumo: Em virtude do número crescente de veículos automotores e uma legislação ambiental cada vez mais rigorosa, as indústrias automobilísticas e os centros de pesquisas avançados buscam desenvolver novos materiais e processos de fabricação que visam à produção de peças com maior resistência mecânica, melhor conformabilidade do material e a redução das espessuras dos materiais empregados na fabricação, sem comprometer a rigidez e estabilidade estrutural das carroçarias. Esse conceito tem por objetivo minimizar os custos de produção, aumentar a segurança e reduzir o peso total do conjunto montado, diminuindo os índices de emissões de poluentes lançados no meio ambiente, em decorrência da melhor relação peso x potência do veículo e proporcionando melhores condições de conforto e dirigibilidade aos usuários. Baseado nessas características, o objetivo deste estudo foi viabilizar a utilização simultânea de dois processos de fabricação não convencionais: Hidroconformação de "Tailored Welded Blank:' (TWB). Para tanto, comparou-se a conformabilidade do TWB submetido à estampagem convencional e a hidroconformação, empregando-se o Diagrama Limite de Conformação, obtido a partir do ensaio Nakazima modificado, para determinar o limite de conformação da matéria­prima, e a Frente Máxima de Deformação (FMD) para determinar a deformação máxima ocorrida nos produtos. Para isso, foi desenvolvido um ferramental híbrido que possibilita a fabricação de peças pelos métodos da estampagem convencional e da hidroconformação, a partir de chapas de aço ST -06 e ST -07 com espessuras 1,5 e 0,9mm respectivamente, soldadas a laser para compor o TWB. Com a análise comparativa entre a CLC da matéria-prima e a FMD dos produtos estampados convencionalmente e hidroconformados, foi possível identificar que a hidroconformação de chapas supera a estampagem convencional em relação a conformabilidade dos "Tailored Welded Blanks", pois permitiu obter produtos com domos mais elevados e regulares, com uma menor redução de espessura e sem o aparecimento de falhas / Abstract: The increasing number of vehic1es and a more rigorous environmental legislation, are forcing automobile industries and research centers to develop new materials and manufacturing processes to the production of parts with higher mechanical properties, better formability and sheet thickness reduction, without comprirnising the rigidity and structural stability of the auto bodies. The main objective is to minimize the production costs, to increase the safety and to reduce vehic1e weight, reducing pollutants emissions, resulting in a best relation weight x power and providing better conditions of comfort and driveability. Based in these characteristics, the objective of this work was to study the simultaneous use of two not conventional manufacturing processes: hydroforming of Tailored Welded Blank (TWB). Therefore it was compared the formability of TWB in conventional stamping and hydroforrning, from the Forming Limit Diagram (FLD), plotted from the modified Nakazima test, to determine the forming limit of the raw material, and the Maximum Front of Deformation (MFD) to determine the maximum deformation in the products. A hybrid tool was designed and assembled to manufacture parts by conventional stamping and hydroforming steel plates ST -06 and ST-07 com thickness 1,5 and 0,9mm respectively, welded by laser to form the TWBs. With the comparative analysis between FLD of the raw material and MFD of the products conventionally stamped and hydroformed, it was possible to identify that hydroforming overcomes the conventional stamping in respect to the formability of Tailored Welded Blanks, and therefore it was possible to form products with higher and regular domes, with lower reduction of thickness, and without any failures / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

The doctoral thesis deals with utilization of hydroforming technology for manufacturing of a new type of solar absorber, which has directly flow meandering structure and a structured surface consisting of pyramidal elements. Austenitic stainless steel X5CrNi18-10 is used as a material for absorbers production. At the beginning of the thesis, a literary research is performed, which is focused on particular methods of hydroforming technology, their applicability for this problem, forming limits determination and usability of numerical simulation. Based on the literature study, the production technology was developed by using parallel hydroforming technology and it was optimized by using a numerical simulation in the ANSYS software. Hydroforming parameters for two variants of the structured surface with pyramidal cavities with apex angle of 90° and 60° were determined from the calculations and the material tests.

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The doctoral thesis deals with utilization of hydroforming technology for manufacturing of a new type of solar absorber, which has directly flow meandering structure and a structured surface consisting of pyramidal elements. Austenitic stainless steel X5CrNi18-10 is used as a material for absorbers production. At the beginning of the thesis, a literary research is performed, which is focused on particular methods of hydroforming technology, their applicability for this problem, forming limits determination and usability of numerical simulation. Based on the literature study, the production technology was developed by using parallel hydroforming technology and it was optimized by using a numerical simulation in the ANSYS software. Hydroforming parameters for two variants of the structured surface with pyramidal cavities with apex angle of 90° and 60° were determined from the calculations and the material tests.

Paper materials have a long history of use in packaging products, although traditional paper-based packaging is limited in its shape and design. In order to enable more advanced paper-based packaging, various 3-D forming processes for paper materials have been studied. Since 3-D forming processes typically include the application of moisture and/or temperature, the effects of moisture and temperature on the mechanical response of paper have also been investigated. In Paper A, an experimental study of the combined effects of moisture and temperature on the uniaxial mechanical properties of paper was conducted. These experiments provided new insights into how moisture and temperature affect both the elastic and plastic properties of paper materials. These experiments also provided the framework from which the effects of moisture and temperature were modelled in Paper C. In Paper B, an explicit finite element model of the paperboard deep-drawing process was developed. An orthotropic material model with in-plane quadrant hardening was developed and verified for paper. The simulation results matched the trends from experimental deep-drawing up to when micro-scale wrinkling occured. Since most experimental failures occur prior to wrinkling, this model provided quantitative understanding of failure in the paperboard deep-drawing process. In Paper C, an explicit finite element model of paper hydroforming, utilizing the same material model for paper materials as in Paper B, was developed and verified. The simulation results matched well with experimental results, and a parametric study with the finite element model produced quantitative understanding of the hydroforming process for paper materials. Additionally, drying was identified as an important phenomenon for determining the extent of formability of paper materials. / Papper har länge använts som förpackningsmaterial men traditionella pappers- och kartongförpackningar är begränsade i form och design. Olika 3-D formnings processor har studerats för att möjliggöra mer avancerade pappersbaserade förpackningar. Effekterna av fukt och temperatur på pappers mekaniska egenskaper har också undersökts eftersom fukt och temperatur har stor betydelse för slutresultatet i 3-D formningsprocesser. I Artikel A har den kombinerade effekten av fukt och temperatur på de uniaxiella mekaniska egenskaperna av papper undersökts experimentellt. Dessa experiment visar hur fukt och temperatur påverkar både elastiska och plastiska egenskaper hos papper samt ligger till grund för modelleringen av inverkan av fukt och temperatur i Artikel C. I Artikel B har en explicit finita element modell för djupdragning av kartong utvecklas. En ortotropisk materialmodell baserad på en rektangulär flytyta har utvecklats och verifierats för kartong. Simuleringen följde trenderna i experimenten fram till den punkt där mikroskopiska rynkor bildas. Resultaten från analyserna med modellen ger kvantitativ förståelse för materialbrott i djupdragningsprocessen eftersom de flesta experimentella materialbrott inträffar innan mikroskopiska rynkor bildas. I Artikel C har ett explicit finita element modell av hydroformning av papper baserad på materialmodellen från Paper B utvecklats och verifierats mot experimentell hydroformning av papper. En parameterstudie med finitaelement-modellen producerade kvantitativ förståelse för hydroformningsprocessen för papper. Dessutom identifieras torkning som ett viktigt fenomen för att fastställa graden av formbarheten för pappersmaterial. / <p>QC 20150907</p>

Metall- und Maschinenbauunternehmen müssen im Durchschnitt pro Jahr ca. zwei Prozent ihres Umsatzes für Strom und Erdgas ausgeben und die Unternehmer gehen von weiteren Preissteigerungen aus. Damit rückt das Thema Energieeinsparung stärker denn je in den Fokus und wird zu einem strategischen Faktor. Um Kosten zu sparen und Wettbewerbsvorteile zu sichern, ist es notwendig, zielgenaue Energieeinsparmaßnahmen einzuleiten. Die ersten Maßnahmen, welche die meisten Maschinenbauunternehmen umsetzen, sind die Erneuerung der Beleuchtungs-, Heizungs- und Lüftungsanlage, die Verbesserung der Drucklufterzeugung sowie die thematische Sensibilisierung der Mitarbeiter. Aber auch in Maschinen mit ihren dazugehörigen elektrischen Antrieben, Lüftern und Aggregaten verbirgt sich eine große Menge an Optimierungspotenzial. Allerdings ist es hier notwendig nicht die Verbraucher im Einzelnen, sondern die Maschine und deren Prozesse im Ganzen zu betrachten. Meist fehlen hierfür aber geeignete Schnittstellen, um die Messwerte von Sensoren (bspw. Temperatur-, Drucksensoren, etc.) und Antrieben auslesen zu können, was dazu führt, dass diese Potenziale nicht ausgeschöpft werden.

The average metal and mechanical engineering company must spend around two per cent of its annual turnover on electricity and natural gas, and companies are expecting further price increases. As a result, the issue of energy saving is becoming more of a strategic factor than ever before. In order to save costs and ensure competitive advantages, it is necessary to introduce precise energy-saving measures. The first steps taken by most mechanical engineering companies are to replace lighting, heating, and ventilation systems, improve compressed air generation and raise employee awareness. However, there is also a great potential for optimization in machines with their individual electrical drives, fans, and units. In this case, though, it is necessary to look at the machine and its processes as a whole rather than the individual electrical energy consumers. In most cases, however, there is a lack of suitable interfaces for analyzing the measured values from sensors (e.g. temperature, pressure sensors, etc.) and drives, which concludes that this potential is not fully exploited.