Engineering Flow and Design

The importance of design in natural and engineered flow systems is undisputed. It is not only essential to life, but also plays a crucial role in our technological world. In Nature, it arises organically, spontaneously, and is the constructal path for systems to persist in time. The generation of the best design is the target of engineered flow systems. Fluid dynamics and thermodynamics have played a crucial role in the search for these flow designs. Analytical, numerical (CFD) and experimental studies played crucial roles in many technological breakthroughs. They provide the frameworks for understanding, simulating and interpreting flow phenomena. The collection of the articles in this issue, along with a complementary and expansive volume devoted to the same subject, reflect and reaffirm the importance and relevance of the study of flow design in natural and man-made flow systems in the twenty-first century

A generalized framework towards structural mechanics of three-layered composite structures

Three-layered composite structures find a broad application. Increasingly, composites are being used whose layer thicknesses and material properties diverge strongly. In the perspective of structural mechanics, classical approaches to analys is fail at such extraordinary composites. Therefore, emphasis of the present approach is on arbitrary transverse shear rigidities and structural thicknesses of the individual layers. Therewith we employ a layer-wise approach for multiple (quasi-)homogeneous layers. Every layer is considered separately whereby this disquisition is based on the direct approach for deformable directed surfaces. We limit our considerations to geometrical and physical linearity. In this simple and familiar setting we furnish a layer-wise theory by introducing constraints at interfaces to couple the layers. Hereby we restrict our concern to surfaces where all material points per surface are coplanar and all surfaces are plane parallel. Closed-form solutions of the governing equations enforce an arrow frame since they are strongly restrictive in the context of available boundary conditions. Thusacomputational solution approach is introduced using the finite element method. In order to determine the required spatially approximated equation of motion, the principle of virtual work is exploited. The discretization is realized via quadrilateral elements with quadratic shape functions. Here by we introduce an approach where nine degrees of freedom per node are used. In combination with the numerical solution approach, this layer-wise theory has emerged as a powerful tool to analyze omposite tructures. In present reatise, e ould ike o arify he road cope f his pproach

Environmental effects on the durability and the mechanical performance of flax fiber/bio-epoxy composites

The growing usage of bio-composite materials in different engineering applications demands a thorough understanding of their performance during their service. Extreme environmental conditions, such as warm, humid, and freezing environments, among others, can degrade the mechanical properties of the bio-composites when they are exposed to harsh environmental conditions. In addition, the use of these composites in underwater applications can also shorten their life cycle. In this work, the durability and mechanical performance (tensile and flexural behavior)of flax/bio-epoxy composites exposed to different environmental conditions were evaluated. These conditions were chosen to replicate those found outdoors that can affect the durability of these materials: water immersion, warm humid environment and freeze-thaw conditions. Moisture and water absorption behavior were evaluated and the water content (or exposure time)was related to the physical changes and mechanical properties. Results show that the mechanical properties of flax/bio-epoxy composites are clearly degraded by water ageing when they are compared to the ?as manufactured? composites. The tensile strength and modulus is decreased approximately by 9% and 57%, respectively for water saturated (immersed in water until saturation)samples compared to as manufactured samples. On contrary, this reduction rate is only 0.8% and 3%, respectively in case of humidity saturated (exposed to humid environment until saturation)samples. Furthermore, water incurred more severe effects on the flexural properties of the composites, since their flexural strength and modulus is decreased by 64% and 70%, respectively, as compared to as manufactured samples. It was found, however, that these properties can be partially regained after drying the water aged composites. Warm humid environments and freezing-thawing cycles have very little effect on the bio-composites.Fil: Moudood, Abdul. Griffith University; AustraliaFil: Rahman, Anisur. Griffith University; AustraliaFil: Khanlou, Hossein Mohammad. Griffith University; AustraliaFil: Hall, Wayne. Griffith University; AustraliaFil: Öchsner, Andreas. Hochschule Esslingen; AlemaniaFil: Francucci, Gaston Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Complex joint geometry

The finite element method is particularly suited to analyse complex joint geometries. Adhesively bonded joints are increasingly being used in engineering applications where the loading mode, the adherends shape and the material behaviour are extremely difficult to simulate with a closed form approach. A detailed description of finite element studies concerning non-conventional adhesive joints is presented in this chapter. Various types of joints, local geometrical features such as the spew fillet and adherend rounding, three dimensional analyses, hybrid joints and repair techniques are discussed. Special techniques to save computer power are also treated. It is shown that the finite element method offers unlimited possibilities for stress analysis but also presents some numerical problems at sharp edges. © 2008 Springer Berlin Heidelberg

Finite element analysis of natural fiber composites using a self-updating model

No embargo required The aim of the current work was to illustrate the effect of the fibre area correction factor on the results of modelling natural fibre-reinforced composites. A mesoscopic approach is adopted to represent the stochastic heterogeneity of the composite, i.e. a meso-structural numerical model was prototyped using the finite element method including quasi-unidirectional discrete fibre elements embedded in a matrix. The model was verified by the experimental results from previous work on jute fibres but is extendable to every natural fibre with cross-sectional non-uniformity. A correction factor was suggested to fine-tune both the analytical and numerical models. Moreover, a model updating technique for considering the size-effect of fibres is introduced and its implementation was automated by means of FORTRAN subroutines and Python scripts. It was shown that correcting and updating the fibre strength is critical to obtain accurate macroscopic response of the composite when discrete modelling of fibres is intended. Based on the current study, it is found that consideration of the effect of flaws on the strength of natural fibres and inclusion of the fibre area correction factor are crucial to obtain realistic results. </jats:p

Uniaxial and multiaxial fatigue life prediction of the trabecular bone based on physiological loading: a comparative study

Fatigue assessment of the trabecular bone has been developed to give a better understanding of bone properties. While most fatigue studies are relying on uniaxial compressive load as the method of assessment, in various cases details are missing, or the uniaxial results are not very realistic. In this paper, the effect of three different load histories from physiological loading applied on the trabecular bone were studied in order to predict the first failure surface and the fatigue lifetime. The fatigue behaviour of the trabecular bone under uniaxial load was compared to that of multiaxial load using a finite element simulation. The plastic strain was found localized at the trabecular structure under multiaxial load. On average, applying multiaxial loads reduced more than five times the fatigue life of the trabecular bone. The results provide evidence that multiaxial loading is dominated in the low cycle fatigue in contrast to the uniaxial one. Both bone volume fraction and structural model index were best predictors of failure (p < 0.05) in fatigue for both types of loading, whilst uniaxial loading has indicated better values in most cases

Abschlussbericht des Forschungsprojekts "Broker für Dynamische Produktionsnetzwerke"

Der Broker für dynamische Produktionsnetzwerke (DPNB) ist ein vom Bundesministerium für Bildung und Forschung (BMBF) gefördertes und durch den Projektträger Karlsruhe (PTKA) betreutes Forschungsprojekt zwischen sieben Partnern aus Wissenschaft und Wirtschaft mit einer Laufzeit von Januar 2019 bis einschließlich Dezember 2021. Über den Einsatz von Cloud Manufacturing sowie Hard- und Software-Komponenten bei den teilnehmenden Unternehmen, sollen Kapazitätsanbieter mit Kapazitätsnachfrager verbunden werden. Handelbare Kapazitäten sind in diesem Falle Maschinen-, sowie Transport- und Montagekapazitäten, um Supply Chains anhand des Anwendungsfalls der Blechindustrie möglichst umfassend abzubilden. Der vorliegende Abschlussbericht fasst den Stand der Technik sowie die Erkenntnisse aus dem Projekt zusammen. Außerdem wird ein Überblick über die Projektstruktur sowie die Projektpartner gegeben

Guest editorial

This special issue of the International Journal of Adhesion and Adhesives (IJAA) contains selected papers presented at the Special Session on ‘Adhesive Bonding’ held at the 4th International Conference on Advanced Computational Engineering and Experimenting (ACE-X 2010) meeting. ACE-X 2010 was chaired by both of us and Prof. H Altenbach and was held in Paris, France, during July 8–9, 2010. The goal of the conference was to provide a unique opportunity to exchange information, present the latest results as well as to discuss issues relevant to engineering mechanics research today. The importance of science and technology of adhesion in engineering applications spurred the chairman of the ACE-X 2010 meeting to include a special session dedicated to this subject, organised by one of us (LFMdS) and Prof. Jean-Yves Cognard. Approximately 70 papers were presented by researchers from more than 20 countries in the “Adhesive Bonding” Special Session. The organisers wish to thank the authors and delegates for their participation and cooperation, which made this Special Session possible

Uniaxial elasto-plastic behavior of adhesively bonded Hollow Sphere Structures (HHS) : numerical simulations and experiments

This paper is on the investigation of adhesively bonded metallic hollow sphere structures. Two different approaches, namely experimental analysis and finite element calculations are applied and the findings of both attempts are compared. In the scope of the numerical approach the influence of the mechanical properties of the adhesive on the mechanical response of the structure is analysed. Based on these results, suggestions for design parameters are derived