Platforms, network effects and small business dynamics in China : case study of the Shanzhai cell phone industry

This paper seeks to argue the significance of platforms on emerging markets through a case study of the Shanzhai cell phone industry in Shenzhen, China. In this industry, value chains are being driven by both the technology platforms and the market platforms. The former include MTK baseband chipset, and so-called Shared PCBA and Shared Mould. The latter include the North Huaqiang Market and the Purchasing and Money Platform. Technology platforms greatly reduced the technological barriers to entry for independent design houses and system integrators, while market platforms markedly improved their poor marketing and purchasing abilities. Due to factors such as social networks, supporting industries, informality and platform governance, strong network effects have been exhibited in the two types of platforms, which have not only fostered numerous start-ups, but have also led to effective exploitation of emerging markets.

Knowledge spillover in Indian automobile industry : the process and the coverage

In India, as the production of passenger cars increased, many local small and medium enterprises (SMEs) entered the parts and components manufacturing sector. The sources of knowledge for large enterprises and SMEs are different. Naturally, spillover effects among large enterprises and between large enterprises and SMEs are different. This paper focuses on knowledge spillover among large enterprises and from large enterprises to SMEs. Subcontractor can absorb relation-specific skills through repeated interaction with parent company. The results of field survey emphasizes that relation-specific skills are a determinant factor of spillover effects from assemblers and large auto component manufacturers to SMEs. Econometric analysis shows that spillover effects among medium and large automobile units and from medium and large automobile units to small units went beyond boundary of cluster.

Exploring the sources of China's challenge to Japan : models of industrial organisation in the motorcycle industry

In view of the recent rise of China, this paper looks into one of the most important yet relatively overlooked ingredients of the Chinese success: industrial organisation. It will examine the case of the motorcycle industry, in which the rise of Chinese manufacturers even disrupted the established dominance of Japanese industry leaders. Adopting the modified version of the global value chain governance framework, this paper shows that the rise of China has been driven by a distinctive arm’s-length model of industrial organisation, which is in sharp contrast to the conventional captive model that has sustained the Japanese leadership.

The Japanese and Chinese models of industrial organisation : fighting for supremacy in the Vietnamese motorcycle industry

This paper explores the consequences of the emerging rivalry between Japanese and Chinese manufacturers. It focuses specifically on industrial organisation, one of the key factors that underlie the competitiveness of manufacturing industries. The question to be asked is what happens when distinctive models of industrial organisation, coming from Japan and China, clash in a developing country. An in-depth longitudinal analysis of the Vietnamese motorcycle industry adopting a modified version of the global value chain governance theory shows that a decade-long industrial transformation resulted in organisational diversity. The implications of the analysis for the literature on industrial organisation are discussed.

Approach to the use of indicators for the assessment of the environmental level of construction products

The European construction industry is supposed to consume the 40% of the natural European resources and to generate the 40% of the European solid waste. Conscious of the great damage being suffered by the environment because of construction activity, this work tries to provide the building actors with a new tool to improve the current situation. The tool proposed is a model for the comprehensive evaluation of construction products by determining their environmental level. In this research, the environmental level of a construction product has been defined as its quality of accomplishing the construction requirements needed by causing the minimum ecological impact in its surrounding environment. This information allows building actors to choose suitable materials for building needs and also for the environment, mainly in the project stage or on the building site, contributing to improve the relationship between buildings and environment. For the assessment of the environmental level of construction products, five indicators have been identified regarding their global environmental impact through the product life cycle: CO2 emissions provoked during their production, volume and toxicity of waste generated on the building site, durability and recycling capacity after their useful life. Therefore, the less environmental impact one construction product produces, the higher environmental level performs. The model has been tested in 30 construction products that include environmental criteria in their description. The results obtained will be discussed in this article. Furthermore, this model can lay down guidelines for the selection of ecoefficient construction products and the design of new eco-competitive and eco-committed ones

Legal Aspects which Implement Good Practice Measures in the Management of Construction and Demolition Waste

The construction industry, one of the most important ones in the development of a country, generates unavoidable impacts on the environment. The social demand towards greater respect for the environment is a high and general outcry. Therefore, the construction industry needs to reduce the impact it produces. Proper waste management is not enough; we must take a further step in environmental management, where new measures need to be introduced for the prevention at source, such as good practices to promote recycling. Following the amendment of the legal frame applicable to Construction and Demolition Waste (C&D waste), important developments have been incorporated in European and International laws, aiming to promote the culture of reusing and recycling. This change of mindset, that is progressively taking place in society, is allowing for the consideration of C&D waste no longer as an unusable waste, but as a reusable material. The main objective of the work presented in this paper is to enhance C&D waste management systems through the development of preventive measures during the construction process. These measures concern all the agents intervening in the construction process as only the personal implication of all of them can ensure an efficient management of the C&D waste generated. Finally, a model based on preventive measures achieves organizational cohesion between the different stages of the construction process, as well as promoting the conservation of raw materials through the use and waste minimization. All of these in order to achieve a C&D waste management system, whose primary goal is zero waste generation

Intensive use of aluminium in car body construction

The developments in materials over the last decade have been considerable within the automotive industry, being one of the leaders in innovative product applications. Sustainable product development of an automotive structure requires a balanced approach towards technological, economical and ecological aspects. The introduction of new materials and processes is dependent on satisfying different factors. Competitive and legislative pressures, creating the need for change, affect these factors considerably. The process, direction and speed of change are often reactive. Current paper shows the application of aluminium alloys, for the use in the bottom structure of a car to face the problem for the weight of the entire bottom structure under static load conditions, including stiffness, strength and buckling constraints. In addition to minimized mass and materials' price, the assessment of an environmental impact of materials-candidates during the entire life cycle of the structure is considered.

A proposal for improving safety in construction projects by strengthening coordinators’ competencies in health and safety issues

The figure of the coordinator in health and safety issues in the construction sector first appeared in our legislation through the incorporation of the European Directives (in our case Royal Decree 1627/97 on the minimum health and safety regulations in construction works), and is viewed differently in different countries of the European Union regarding the way they are hired and their role in the construction industry. Coordinating health and safety issues is also a management process that requires certain competencies that are not only based on technical or professional training, but which, taking account of the work environment, require the use of strategies and tools that are related to experience and personal skills. Through a piece of research that took account of expert opinions in the matter, we have found which competencies need to be possessed by the health and safety coordinator in order to improve the safety in the works they are coordinating. The conclusions of the analyses performed using the appropriate statistical methods (comparing means and multivariate analysis techniques), will enable training programmes to be designed and ensure that the health and safety coordinators selected have the competencies required to carry out their duties.

A proposal for improving safety in construction projects by strengthening coordinators’ competencies in health and safety issues

The figure of the coordinator in health and safety issues in the construction sector first appeared in our legislation through the incorporation of the European Directives (in our case Royal Decree 1627/97 on the minimum health and safety regulations in construction works), and is viewed differently in different countries of the European Union regarding the way they are hired and their role in the construction industry. Coordinating health and safety issues is also a management process that requires certain competencies that are not only based on technical or professional training, but which, taking account of the work environment, require the use of strategies and tools that are related to experience and personal skills. Through a piece of research that took account of expert opinions in the matter, we have found which competencies need to be possessed by the health and safety coordinator in order to improve the safety in the works they are coordinating. The conclusions of the analyses performed using the appropriate statistical methods (comparing means and multivariate analysis techniques), will enable training programmes to be designed and ensure that the health and safety coordinators selected have the competencies required to carry out their duties.

Efficient management of available technologies. Aplication to mining operations for industry supplies

Nowadays, processing Industry Sector is going through a series of changes, including right management and reduction of environmental affections. Any productive process which looks for sustainable management is incomplete if Cycle of Life of mineral resources sustainability is not taken into account. Raw materials for manufacturing are provided by mineral resources extraction processes, such as copper, aluminum, iron, gold, silver, silicon, titanium? Those elements are necessary for Mankind development and are obtained from the Earth through mineral extractive processes. Mineral extraction processes are operations which must take care about the environmental consequences. Extraction of huge volumes of rock for their transformation into raw materials for industry must be optimized to reduce ecological cost of the final product as l was possible. Reducing the ecological balance on a global scale has no sense to design an efficient manufacturing in secondary industry (transformation), if in first steps of the supply chain (extraction) impact exceeds the savings of resources in successive phases. Mining operations size suggests that it is an environmental aggressive activity, but precisely because of its great impact must be the first element to be considered. That idea implies that a new concept born: Reduce economical and environmental cost This work aims to make a reflection on the parameters that can be modified to reduce the energy cost of the process without an increasing in operational costs and always ensuring the same production capacity. That means minimize economic and environmental cost at same time. An efficient design of mining operation which has taken into account that idea does not implies an increasing of the operating cost. To get this objective is necessary to think in global operation view to make that all departments involved have common guidelines which make you think in the optimization of global energy costs. Sometimes a single operational cost must be increased to reduce global cost. This work makes a review through different design parameters of surface mining setting some key performance indicators (KPIs) which are estimated from an efficient point of view. Those KPIs can be included by HQE Policies as global indicators. The new concept developed is that a new criteria has to be applied in company policies: improve management, improving OPERATIONAL efficiency. That means, that is better to use current resources properly (machinery, equipment,?) than to replace them with new things but not used correctly. As a conclusion, through an efficient management of current technologies in each extractive operation an important reduction of the energy can be achieved looking at downstream in the process. That implies a lower energetic cost in the whole cycle of life in manufactured product.

Estudio de los riesgos técnicos aplicados al diseño y construcción de cimentaciones para máquinas

En el Código Técnico de la Edificación se define el riesgo como medida del alcance del peligro que representa un evento no deseado para las personas, expresado en términos de probabilidad vinculada a las consecuencias de un evento, también se expresa como Exigencia Básica de Resistencia y Estabilidad, que estas serán las adecuadas para que no se generen riesgos indebidos manteniendo la resistencia y estabilidad frente a las acciones e influencias previsibles durante la construcción y usos previstos de los edificios, y que además, los posibles eventos extraordinarios que puedan producirse no originen consecuencias desproporcionadas respecto a la causa original. Es ahora donde la gestión de riesgos juega un papel muy importante en la sociedad moderna, siendo esta cada vez más exigente con los resultados y calidad de productos y servicios, además de cumplir también con la responsabilidad jurídica que trae la concepción, diseño y construcción de proyectos de gran envergadura como los son la obra civil y edificación. La obra civil destinada al sector industrial debe ser ejecutada con la mayor precisión posible, pues requiere la instalación de complejos equipos y sistemas productivos que pueden producir esfuerzos dinámicos que muchas veces no se consideran en el diseño de los cimientos que lo soportan, razón por la cual interviene la gestión de riesgos para conocer y reducir los posibles riesgos de fallos que se puedan generar y así intentar aproximarse cada vez más al desarrollo de diseños eficientes y confiables, afianzando la exactitud y minimizando errores en la producción y elaboración de piezas, sistemas y equipos de las distintas áreas productivas de la industria. El presente trabajo de investigación se centra en el estudio de los riesgos técnicos existentes en el diseño y ejecución de cimentaciones para maquinarias, mediante la aplicación de varios métodos de investigación, a fin de intentar cubrir los aspectos más importantes que puedan incurrir en una posible causa de fallo de la estructura, evaluando el acoplamiento entre el sistema máquina-cimiento-suelo. Risk is defined, by the Technical Building Code (Código Técnico de la Edificación, CTE) as a measure of the scope of the hazard of an undesired event for people, expressed in terms of probability related to the consequences of an event, also is expressed as a Basic Requirement Strength and Stability these will be appropriate to not cause undue risk maintaining strength and stability against predictable actions and influences during construction and expected uses of the buildings. Nowadays, Risk Management is an important process in modern society, becoming ever more demanding about the results and quality of products and services, and also complies with the legal responsibility that brings the conception, design and construction of large projects as are civil engineering and construction projects. Civil work as a part of industry must be performed as accurately as possible, requiring the installation of sophisticated equipment and production systems which can produce dynamic forces that often are not considered in the design of the foundations, this is the reason why risk management is involved to understand and reduce the risks of failures that may arise and try to move closer to the development of efficient and reliable designs, strengthening the accuracy and minimizing errors in the production and processing of parts, systems and equipments from different production areas of the industry. This paper is a study of existing technical risks in the design and execution of foundations for machinery, through the application of various research methods, in order to try to cover the most important aspects that may produce the failure of the structure, evaluating the union between the machine-foundation system and soil.

Industry-peppers harvest mechanization.

Production of peppers for deshidration (paprika) and for extraction of natural colorants is of great importance in some Mediterranean irrigation areas. In the area of Badajoz (Spain) traditional production, handling and postharvest systems are no longer feasible, although a very good quality and potential market exist for this product. All aspects of mechanized production and handling have been addressed: direct seeding and transplanting, cultivation systems and mechanical harvesting are searched to be adopted in a new production system. A study of size, shape and fruiting pattern of the new varieties was performed. A feasibility study of mechanized harvesting was also made. Results of field testing of different types of harvesters and performance of existing picking heads are presented, some of which yield a feasible solution for the growers of industry peppers in the area. The design, construction and field testing results of a new picking head based on the double-helix principle is presented.

Uncertainty Estimation for Performance Evaluation of a Confocal Microscope as Metrology Equipment

Both in industry and research, the quality control of micrometric manufactured parts is based on the measurement of parameters whose traceability is sometimes difficult to guarantee. In some of these parts, the confocal microscopy shows great aptitudes to characterize a measurand qualitatively and quantitatively. The confocal microscopy allows the acquisition of 2D and 3D images that are easily manipulated. Nowadays, this equipment is manufactured by many different brands, each of them claiming a resolution probably not in accord to their real performance. The Laser Center (Technical University of Madrid) has a confocal microscope to verify the dimensions of the micro mechanizing in their own research projects. The present study pretends to confirm that the magnitudes obtained are true and reliable. To achieve this, a methodology for confocal microscope calibration is proposed, as well as an experimental phase for dimensionally valuing the equipment by 4 different standard positions, with its seven magnifications and the six objective lenses that the equipment currently has, in the x–y and z axis. From the results the uncertainty will be estimated along with an effect analysis of the different magnifications in each of the objective lenses.

Propuesta de un modelo de sistema de información interorganizacional: aplicación en el sector de la domótica para la gestión de servicios del hogar digital

El sector de la edificación es uno de los principales sectores económicos en España y, además, es un componente básico de la actividad económica y social, debido a su importante papel como generador de empleo, proveedor de bienes e incentivador del crecimiento. Curiosamente, es uno de los sectores con menos regulación y organización y que, además, está formado mayoritariamente por empresas de pequeña y mediana dimensión (pymes) que, por su menor capacidad, a menudo, se quedan detrás de las grandes empresas en términos de adopción de soluciones innovadoras. La complejidad en la gestión de toda la información relacionada con un proyecto de edificación ha puesto de manifiesto claras ineficiencias que se traducen en un gasto innecesario bastante representativo. La información y los conocimientos aprendidos rara vez son transmitidos de una fase a otra dentro del proyecto de edificación y, mucho menos, reutilizados en otros proyectos similares. De este modo, no sólo se produce un gasto innecesario, sino que incluso podemos encontrar información contradictoria y obsoleta y, por tanto, inútil para la toma de decisiones. A lo largo de los años, esta situación ha sido motivada por la propia configuración del sector, poniendo de manifiesto la necesidad de una solución que pudiera solventar este reto de gestión interorganizacional. Así, la cooperación interorganizacional se ha convertido en un factor clave para mejorar la competitividad de las organizaciones, típicamente pymes, que componen el sector de la edificación. La información es la piedra angular de cualquier proceso de negocio. Durante la última década, una amplia gama de industrias han experimentado importantes mejoras de productividad con la aplicación eficiente de las TIC, asociadas, principalmente, a incrementos en la velocidad de proceso de información y una mayor coherencia en la generación de datos, accesibilidad e intercambio de información. La aplicación eficaz de las TIC en el sector de la edificación requiere una combinación de aspectos estratégicos y tácticos, puesto que no sólo se trata de utilizar soluciones puntuales importadas de otros sectores para su aplicación en diferentes áreas, sino que se buscaría que la información multi-agente estuviera integrada y sea coherente para los proyectos de edificación. El sector de la construcción ha experimentado un descenso significativo en los últimos años en España y en Europa como resultado de la crisis financiera que comenzó en 2007. Esta disminución está acompañada de una baja penetración de las TIC en la interorganizacionales orientadas a los procesos de negocio. El descenso del mercado ha provocado una desaceleración en el sector de la construcción, donde sólo las pymes flexibles han sido capaces de mantener el ritmo a pesar de la especialización y la innovación en los servicios adaptados a las nuevas demandas del mercado. La industria de la edificación está muy fragmentada en comparación con otras industrias manufactureras. El alto grado de esta fragmentación está íntimamente relacionado con un impacto significativo en la productividad y el rendimiento. Muchos estudios de investigación han desarrollado y propuesto una serie de modelos de procesos integrados. Por desgracia, en la actualidad todavía no se está en condiciones para la formalización de cómo debe ser la comunicación y el intercambio de información durante el proceso de construcción. El paso del proceso secuencial tradicional a los procesos de interdependencia recíproca sin lugar a duda son una gran demanda asociada a la comunicación y el flujo de información en un proyecto de edificación. Recientemente se está poniendo mucho énfasis en los servicios para el hogar como un primer paso hacia esta mejora en innovación ya que la industria de los servicios digitales interactivos tiene un alto potencial para generar innovación y la ventaja estratégica para las empresas existentes. La multiplicidad de servicios para el hogar digital (HD) y los proveedores de servicios demandan, cada vez más, la aparición de una plataforma capaz de coordinar a todos los agentes del sector con el usuario final. En consecuencia, las estructuras organizacionales tienden a descentralizarse en busca de esa coordinación y, como respuesta a esta demanda, se plantea, también en este ámbito, el concepto de cooperación interorganizacional. Por lo tanto, ambos procesos de negocio -el asociado a la construcción y el asociado a la provisión de servicios del hogar digital, también considerado como la propia gestión de ese hogar digital o edificio, inteligente o no- deben de ser vistos en su conjunto mediante una plataforma tecnológica que les dé soporte y que pueda garantizar la agregación e integración de los diversos procesos, relacionados con la construcción y gestión, que se suceden durante el ciclo de vida de un edificio. Sobre esta idea y atendiendo a la evolución permanente de los sistemas de información en un entorno de interrelación y cooperación daría lugar a una aplicación del concepto de sistema de información interorganizacional (SIIO). El SIIO proporciona a las organizaciones la capacidad para mejorar los vínculos entre los socios comerciales a lo largo de la cadena de suministro, por lo que su importancia ha sido reconocida por organizaciones de diversos sectores. Sin embargo, la adopción de un SIIO en diferentes ámbitos ha demostrado ser complicada y con una alta dependencia de las características particulares de cada sector, siendo, en este momento, una línea de investigación abierta. Para contribuir a esta línea de investigación, este trabajo pretende recoger, partiendo de una revisión de la literatura relacionada, un enfoque en un modelo de adopción de un SIIO para el objeto concreto de esta investigación. El diseño de un SIIO está basado principalmente, en la identificación de las necesidades de información de cada uno de sus agentes participantes, de ahí la importancia en concretar un modelo de SIIO en el ámbito de este trabajo. Esta tesis doctoral presenta el modelo de plataforma virtual de la asociación entre diferentes agentes del sector de la edificación, el marco de las relaciones, los flujos de información correspondientes a diferentes procesos y la metodología que subyace tras el propio modelo, todo ello, con el objeto de contribuir a un modelo unificado que dé soporte tanto a los procesos relacionados con la construcción como con la gestión de servicios en el hogar digital y permitiendo cubrir los requisitos importantes que caracterizan este tipo de proyectos: flexibilidad, escalabilidad y robustez. El SIIO se ha convertido en una fuente de innovación y una herramienta estratégica que permite a las pymes obtener ventajas competitivas. Debido a la complejidad inherente de la adopción de un SIIO, esta investigación extiende el modelo teórico de adopción de un SIIO de Kurnia y Johnston (2000) con un modelo empírico para la caracterización de un SIIO. El modelo resultante tiene como objetivo fomentar la innovación de servicios en el sector mediante la identificación de los factores que influyen en la adopción de un SIIO por las pymes en el sector de la edificación como fuente de ventaja competitiva y de colaboración. Por tanto, esta tesis doctoral, proyectada sobre una investigación empírica, proporciona un enfoque para caracterizar un modelo de SIIO que permita dar soporte a la gestión integrada de los procesos de construcción y gestión de servicios para el hogar digital. La validez del modelo de SIIO propuesto, como fuente y soporte de ventajas competitivas, está íntimamente relacionada con la necesidad de intercambio de información rápido y fiable que demandan los agentes del sector para mejorar la gestión de su interrelación y cooperación con el fin de abordar proyectos más complejos en el sector de la edificación, relacionados con la implantación del hogar digital, y contribuyendo, así a favorecer el desarrollo de la sociedad de la información en el segmento residencial. ABSTRACT The building industry is the largest industry in the world. Land purchase, building design, construction, furnishing, building equipment, operations maintenance and the disposition of real estate have an unquestionable prominence not only at economic but also at social level. In Spain, the building sector is one of the main drivers of economy and also a basic component of economic activity and its role in generating employment, supply of goods or incentive for growth is crucial in the evolution of the economy. Surprisingly, it is one of the sectors with less regulation and organization. Another consistent problem is that, in this sector, the majority of companies are small and medium (SMEs), and often behind large firms in terms of their adoption of innovative solutions. The complexity of managing all information related to this industry has lead to a waste of money and time. The information and knowledge gathered is frequently stored in multiple locations, involving the work of thousands of people, and is rarely transferred on to the next phase. This approach is inconsistent and makes that incorrect information is used for decisions. This situation needs a viable solution for interorganizational information management. So, interorganizational co-operation has become a key factor for organization competitiveness within the building sector. Information is the cornerstone of any business process. Therefore, information and communication technologies (ICT) offer a means to change the way business is conducted. During the last decade, significant productivity improvements were experienced by a wide range of industries with ICT implementation. ICT has provided great advantages in speed of operation, consistency of data generation, accessibility and exchange of information. The wasted money resulting from reentering information, errors and omissions caused through poor decisions and actions, and the delays caused while waiting for information, represent a significant percentage of the global benefits. The effective application of ICT in building construction sector requires a combination of strategic and tactical developments. The building sector has experienced a significant decline in recent years in Spain and in Europe as a result of the financial crisis that began in 2007. This drop goes hand in hand with a low penetration of ICT in inter-organizational-oriented business processes. The market decrease has caused a slowdown in the building sector, where only flexible SMEs have been able to keep the pace though specialization and innovation in services adapted to new market demands. The building industry is highly fragmented compared with other manufacturing industries. This fragmentation has a significant negative impact on productivity and performance. Many research studies have developed and proposed a number of integrated process models. Unfortunately, these studies do not suggest how communication and information exchange within the construction process can be achieved, without duplication or lost in quality. A change from the traditional sequential process to reciprocal interdependency processes would increase the demand on communication and information flow over the edification project. Focusing on home services, the digital interactive service industry has the potential to generate innovation and strategic advantage for existing business. Multiplicity of broadband home services (BHS) and suppliers suggest the need for a figure able to coordinate all the agents in sector with the final user. Consequently, organizational structures tend to be decentralized. Responding to this fact, the concept of interorganizational co-operation also is raising in the residential market. Therefore, both of these business processes, building and home service supply, must be complemented with a technological platform that supports these processes and guarantees the aggregation and integration of the several services over building lifecycle. In this context of a technological platform and the permanent evolution of information systems is where the relevance of the concept of inter-organizational information system (IOIS) emerges. IOIS improves linkages between trading partners along the supply chain. However, IOIS adoption has proved to be difficult and not fully accomplished yet. This research reviews the literature in order to focus a model of IOIS adoption. This PhD Thesis presents a model of virtual association, a framework of the relationships, an identification of the information requirements and the corresponding information flows, using the multi-agent system approach. IOIS has become a source of innovation and a strategic tool for SMEs to obtain competitive advantage. Because of the inherent complexity of IOIS adoption, this research extends Kurnia and Johnston’s (2000) theoretical model of IOIS adoption with an empirical model of IOIS characterization. The resultant model aims to foster further service innovation in the sector by identifying the factors influencing IOIS adoption by the SMEs in the building sector as a source of competitive and collaborative advantage. Therefore, this PhD Thesis characterizes an IOIS model to support integrated management of building processes and home services. IOIS validity, as source and holder of competitive advantages, is related to the need for reliable information interchanges to improve interrelationship management. The final goal is to favor tracking of more complex projects in building sector and to contribute to consolidation of the information society through the provision of broadband home services and home automation.

Análisis del comportamiento a fatiga de uniones adhesivas de acero recubierto

Los adhesivos se conocen y han sido utilizados en multitud de aplicaciones a lo lago de la historia. En la actualidad, la tecnología de la adhesión como método de unión de materiales estructurales está en pleno crecimiento. Los avances científicos han permitido comprender mejor los fenómenos de adhesión, así como, mejorar y desarrollar nuevas formulaciones poliméricas que incrementan el rango de aplicaciones de los adhesivos. Por otro lado, el desarrollo de nuevos materiales y la necesidad de aligerar peso, especialmente en el sector transporte, hace que las uniones adhesivas se introduzcan en aplicaciones hasta ahora reservadas a otros sistemas de unión como la soldadura o las uniones mecánicas, ofreciendo rendimientos similares y, en ocasiones, superiores a los aportados por estas. Las uniones adhesivas ofrecen numerosas ventajas frente a otros sistemas de unión. En la industria aeronáutica y en automoción, las uniones adhesivas logran una reducción en el número de componentes (tales como los tornillos, remaches, abrazaderas) consiguiendo como consecuencia diseños más ligeros y una disminución de los costes de manipulación y almacenamiento, así como una aceleración de los procesos de ensamblaje, y como consecuencia, un aumento de los procesos de producción. En el sector de la construcción y en la fabricación de equipos industriales, se busca la capacidad para soportar la expansión y contracción térmica. Por lo tanto, se usan las uniones adhesivas para evitar producir la distorsión del sustrato al no ser necesario el calentamiento ni la deformación de las piezas cuando se someten a un calentamiento elevado y muy localizado, como en el caso de la soldadura, o cuando se someten a esfuerzos mecánicos localizados, en el caso de montajes remachados. En la industria naval, se están desarrollando técnicas de reparación basadas en la unión adhesiva para distribuir de forma más uniforme y homogénea las tensiones con el objetivo de mejorar el comportamiento frente a fatiga y evitar los problemas asociados a las técnicas de reparación habituales de corte y soldadura. Las uniones adhesivas al no requerir importantes aportes de calor como la soldadura, no producen modificaciones microestructurales indeseables como sucede en la zona fundida o en la zona afectada térmicamente de las uniones soldadas, ni deteriora los recubrimientos protectores de metales de bajo punto de fusión o de naturaleza orgánica. Sin embargo, las uniones adhesivas presentan una desventaja que dificulta su aplicación, se trata de su durabilidad a largo plazo. La primera causa de rotura de los materiales es la rotura por fatiga. Este proceso de fallo es la causa del 85% de las roturas de los materiales estructurales en servicio. La rotura por fatiga se produce cuando se somete al material a la acción de cargas que varían cíclicamente o a vibraciones durante un tiempo prolongado. Las uniones y estructuras sometidas a fatiga pueden fallar a niveles de carga por debajo del límite de resistencia estática del material. La rotura por fatiga en las uniones adhesivas no se produce por un proceso de iniciación y propagación de grieta de forma estable, el proceso de fatiga va debilitando poco a poco la unión hasta que llega un momento que provoca una rotura de forma rápida. Underhill explica este mecanismo como un proceso de daño irreversible de los enlaces más débiles en determinados puntos de la unión. Cuando se ha producido el deterioro de estas zonas más débiles, su área se va incrementando hasta que llega un momento en que la zona dañada es tan amplia que se produce el fallo completo de la unión. En ensayos de crecimiento de grieta realizados sobre probetas preagrietadas en viga con doble voladizo (DCB), Dessureault identifica los procesos de iniciación y crecimiento de grietas en muestras unidas con adhesivo epoxi como una acumulación de microfisuras en la zona próxima al fondo de grieta que, luego, van coalesciendo para configurar la grieta principal. Lo que supone, igualmente, un proceso de daño del adhesivo en la zona de mayor concentración de tensiones que, posteriormente, conduce al fallo de la unión. La presente tesis surge con el propósito de aumentar los conocimientos existentes sobre el comportamiento a fatiga de las uniones adhesivas y especialmente las realizadas con dos tipos de adhesivos estructurales aplicados en aceros con diferentes acabados superficiales. El estudio incluye la obtención de las curvas de tensión frente al número de ciclos hasta el fallo del componente, curvas SN o curvas de Wöhler, que permitirán realizar una estimación de la resistencia a la fatiga de un determinado material o estructura. Los ensayos de fatiga realizados mediante ciclos predeterminados de carga sinusoidales, de amplitud y frecuencia constantes, han permitido caracterizar el comportamiento a la fatiga por el número de ciclos hasta la rotura, siendo el límite de fatiga el valor al que tiende la tensión cuando el número de ciclos es muy grande. En algunos materiales, la fatiga no tiende a un valor límite sino que decrece de forma constante a medida que aumenta el número de ciclos. Para estas situaciones, se ha definido la resistencia a la fatiga (o límite de resistencia) por la tensión en que se produce la rotura para un número de ciclos predeterminado. Todos estos aspectos permitirán un mejor diseño de las uniones y las condiciones de trabajo de los adhesivos con el fin de lograr que la resistencia a fatiga de la unión sea mucho más duradera y el comportamiento total de la unión sea mucho mejor, contribuyendo al crecimiento de la utilización de las uniones adhesivas respecto a otras técnicas. ABSTRACT Adhesives are well-known and have been used in many applications throughout history. At present, adhesion bonding technology of structural materials is experiencing an important growth. Scientific advances have enabled a better understanding of the phenomena of adhesion, as well as to improve and develop new polymeric formulations that increase the range of applications. On the other hand, the development of new materials and the need to save weight, especially in the transport sector, have promote the use of adhesive bonding in many applications previously reserved for other joining technologies such as welded or mechanical joints, presenting similar or even higher performances. Adhesive bonding offers many advantages over other joining methods. For example, in the aeronautic industry and in the automation sector, adhesive bonding allows a reduction in the number of components (such as bolts, rivets, clamps) and as consequence, resulting in lighter designs and a decrease in handling and storage costs, as well as faster assembly processes and an improvement in the production processes. In the construction sector and in the industrial equipment manufacturing, the ability to withstand thermal expansion and contraction is required. Therefore, adhesion bonding technology is used to avoid any distortion of the substrate since this technology does not require heating nor the deformation of the pieces when these are exposed to very high and localized heating, as in welding, or when are subjected to localized mechanical stresses in the case of riveted joints. In the naval industry, repair techniques based in the adhesive bonding are being developed in order to distribute stresses more uniform and homogeneously in order to improve the performance against fatigue and to avoid the problems associated with standard repair techniques as cutting and welding. Adhesive bonding does not require the use of high temperatures and as consequence they do not produce undesirable microstructural changes, as it can be observed in molten zones or in heat-affected zones in the case of welding, neither is there damage of the protective coating of metals with low melting points or polymeric films. However, adhesive bonding presents a disadvantage that limits its application, the low longterm durability. The most common cause of fractures of materials is fatigue fracture. This failure process is the cause of 85% of the fracture of structural materials in service. Fatigue failure occurs when the materials are subjected to the action of cyclic loads or vibrations for a long period of time. The joints and structures subjected to fatigue can fail at stress values below the static strength of the material. Fatigue failure do not occurs by a static and homogeneous process of initiation and propagation of crack. The fatigue process gradually weakens the bond until the moment in which the fracture occurs very rapidly. Underhill explains this mechanism as a process of irreversible damage of the weakest links at certain points of the bonding. When the deterioration in these weaker zones occurs, their area increase until the damage zone is so extensive that the full failure of the joint occurs. During the crack growth tests performed on precracked double-cantilever beam specimen, (DCB), Dessureault identified the processes of crack initiation and growth in samples bonded with epoxy adhesive as a process of accumulation of microcracks on the zone near the crack bottom, then, they coalesced to configure the main crack. This is a damage process of the adhesive in the zone of high stress concentration that leads to failure of the bond. This thesis aims to further the understanding of the fatigue behavior of the adhesive bonding, primarily those based on two different types of structural adhesives used on carbon-steel with different surface treatments. This memory includes the analysis of the SN or Wöhler curves (stress vs. number of cycles curves up to the failure), allowing to carry out an estimation of the fatigue strength of a specific material or structure. The fatigue tests carried out by means of predetermined cycles of sinusoidal loads, with a constant amplitude and frequency, allow the characterisation of the fatigue behaviour. For some materials, there is a maximum stress amplitude below which the material never fails for any number of cycles, known as fatigue limit. In the other hand, for other materials, the fatigue does not tend toward a limit value but decreases constantly as the number of cycles increases. For these situations, the fatigue strength is defined by the stress at which the fracture occurs for a predetermined number of cycles. All these aspects will enable a better joint design and service conditions of adhesives in order to get more durable joints from the fatigue failure point of view and in this way contribute to increase the use of adhesive bonding over other joint techniques.