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Search Results: 1 - 10 of 84410 matches for " W. Hufenbach "
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Process Chain Modelling and Analysis for the High-Volume Production of Thermoplastic Composites with Embedded Piezoceramic Modules
W. Hufenbach,M. Gude,N. Modler,Th. Heber
Smart Materials Research , 2013, DOI: 10.1155/2013/201631
Design, manufacture and technological verification of SiC/C composite stirrer
A. Dolata-Grosz,W. Hufenbach,J. ?leziona,M. Gude
Archives of Materials Science and Engineering , 2009,
Abstract: Purpose: In article were presented assumptions and choose results of investigations connected with material selection and technology production of prototype’s ceramic stirrer with destination to work in environment of liquid metal. In the research work the result of the design, manufacture and technological verification of SiC/C composite stirrer have been presented.Design/methodology/approach: The design of the stirrer (2D and 3D models) and strength tests on the blade and fragment of the composite axle was prepared in the programme Solid Works and the FEM, using COSMOS software. Polymer infiltration and pyrolysis (PIP) technique was used for fabrication SiC/C stirrer. Examination of wettability and suitability of the SiC/C composite for application in a liquid metal with sessile drop wettability was conducted. The surface geometry, conducted using a non-contact optical profilometer, FRT Micro’Prof.Findings: Further laboratory tests of the SiC/C composite stirrer, designed and developed in the Institute of Lightweight Engineering and Polymer Technology at TU Dresden have confirmed rightness of the design, assumptions regarding the thermal, mechanical and chemical resistance of the stirrer.Practical implications: The technological tests have proven a considerable reduction of the turbulence flow, which with an unchanged system of controlling the stirrer ensured stability of the liquid metal whirl and repeatability of the process.Originality/value: The application of this new material will enable not only the expansion of laboratory research, but it may also facilitate the implementation of liquid/phase technologies of obtaining MMC composites for the industry and thus, contribute to increasing the durability of stirrers in comparison with the solutions applied so far.
Development of novel piezoceramic actuator modules for the embedding in intelligent lightweight structures
W. Hufenbach,M. Gude,N. Modler,C. Kirvel
Journal of Achievements in Materials and Manufacturing Engineering , 2007,
Abstract: Purpose: Piezoceramic actuators in lightweight structures enable a purposeful manipulation of the dynamic and vibroacoustic structural behaviour. Above it, further studies focus on the application of thin and flexible piezoceramic modules as power sources in morphing structures aiming at a shape adaptation.Design/methodology/approach: A specific example of novel morphing structures is introduced, which rely on multistable deformation phenomena of fibre-reinforced composites with an unsymmetric lay-up. For the large-scale capable utilisation of such active struc tural parts made of fibre-reinforced thermoplastic composites, novel piezoceramic modules, which are specifically tailored to the structural material, and required manufacturing methods are developed.Findings: The piezoceramic modules with the highly regarded compatibility to ther moplastic composites permit their substantially coherent and homogeneous integration in the fibre composite structure without intricate adhesive assembly effort. Furthermore, thermally induced residual compressive stresses during the manufacturing process serve for pur posefully prestressing the piezoceramic components to reduce the module’s sensitivity to tensile loading.Research limitations/implications: For the manufacture of those novel piezoceramic modules, a continuously operating fabrication method has been developed. By the process-related integration of a hot press, residual compression stresses are thermally induced into the modules that considerably contribute to the decrease of the piezoceramic module’s sensitivity to tension.Originality/value: The successful development of the novel TPM offers a significant advancement in the efficieny within the large scale production of novel intelligent lightweight structures.
Frequency dependence of the self-heating effect in polymer-based composites
A. Katunin,W. Hufenbach,P. Kostka,K. Holeczek
Journal of Achievements in Materials and Manufacturing Engineering , 2010,
Abstract: Purpose: The self-heating effect caused by viscous energy dissipation in polymer-based composite structures subjected to harmonic loads is considered to have a great influence on the residual life of the component. The purpose of the conducted investigations is the determination of the dynamic mechanical behaviour of a polymer-based composite material under different excitation frequencies and temperatures.Design/methodology/approach: The dynamic mechanical analysis was employed for measurements of temperature and frequency dependence of the complex rigidity parameters. Obtained loss rigidity curves for different load frequencies enable the determination of the glass-transition temperatures and finally frequency-dependence of the loss rigidity determined on the basis of the kinetic molecular theory and Williams-Landel-Ferry (WLF) hypothesis.Findings: The dependency between glass-transition temperature and excitation frequency has been investigated. The activation energy of the phase transition as well as the temperature dependence of the shift factor was calculated. The glass-transition temperature and constants of WLF equation enable the determination of temperature and frequency dependence of the loss rigidity according to the time-temperature superposition principle.Research limitations/implications: The ranges of temperatures were limited to 30-150 °C and excitation frequencies to 1-200 Hz, the behaviour of the composite material outside these ranges can be estimated based on the theoretical assumptions only. Obtained dependencies are correct only for linearly viscoelastic materials.Practical implications: Obtained dependencies can be useful for estimation of the mechanical and thermal degradation of polymer-based composites and can be subsequently applied for the determination of fatigue, crack growth and residual life of composite structures.Originality/value: The determination of temperature and frequency dependence of the loss rigidity gives an opportunity to obtain the self-heating temperature distribution of the polymer-based composite structures under harmonic loading.
Development of textile-reinforced carbon fibre aluminium composites manufactured with gas pressure infiltration methods
W. Hufenbach,M. Gude,A. Czulak,J. ?leziona
Journal of Achievements in Materials and Manufacturing Engineering , 2009,
Abstract: Purpose: The aim of his paper is to show potential of textile-reinforced carbon fibre aluminium composite with advantage of the lightweight construction of structural components subjected to thermo-mechanical stress.Design/methodology/approach: The manufacture of specimens of the carbon fibre-reinforced aluminium was realised with the aid of an advanced differential gas pressure infiltration technique, which was developed at ILK, TU Dresden.Findings: The gas pressure infiltration technology enables to fabricate complex carbon aluminium composites with fibre or textile reinforcement using moulds of graphite, but in future development the optimization of infiltration process is required. The load-adapted combination of 3D reinforced semi-finished fibre products (textile preforms) made from carbon fibres (CF) with aluminium light metal alloys (Al) offers a considerable lightweight construction potential, which up to now has not been exploited.Research limitations/implications: Gas pressure infiltration technology enables to fabricate complex carbon aluminium composites with fibre or textile reinforcement using precision moulds of graphite, but in future development the optimization of infiltration process is required.Practical implications: Load-adapted CF/Al-MMC, due to the relatively high stiffness and strength of the metal matrix, allow the introduction of extremely high forces, thereby enabling a much better exploitation of the existing lightweight construction potential of this material in comparison to other composite materials.Originality/value: Constantly rising demands on extremely stressed lightweight structures, particularly in traffic engineering as well as in machine building and plant engineering, increasingly require the use of endless fibre-reinforced composite materials which, due to their selectively adaptable characteristics profiles, are clearly superior to conventional monolithic materials.
Extended proof of fibre-reinforced laminates with holes
L. Kroll,P. Kostka,M. Lepper,W. Hufenbach
Journal of Achievements in Materials and Manufacturing Engineering , 2009,
Abstract: Purpose: A calculation method for the strength prediction of tensioned laminated plates with circular notches is presented.Design/methodology/approach: An extensive basis of experimental data from tensile fracture tests on carbon fibre reinforced specimens with circular notches was used to analyse factors determining the notched strength. The proposed extension of the known Whitney-Nuismer and Karlak Point Stress Criteria improves the strength prediction accuracy through introduction of a special coefficient function that takes into account the dependence between stress gradients in the notch near-field and the distance of the outer boundary.Findings: It was found that the theoretical, notch size and outer boundary independent stress concentration factor is not sufficient for a reliable prediction of the notched strength. The presented results show that calculation procedure based on fundamental mechanical relations of the elasticity theory with few experimentally determined factors delivers results which good agree with experiments.Research limitations/implications: The calculation procedure was verified on the representative population of tensile specimens made of several types of carbon fibre reinforced laminates used in the aerospace industry.Practical implications: As openings represent relevant sites of failure in the construction, an accurate calculation of the notched strength is essential for the lightweight-oriented design of fibre-reinforced elements. The presented procedure is relevant for construction of practically important tensioned elements with circular holes.Originality/value: The presented formulation of the phenomenological “characteristic distance” concept and its thorough experimental verification is original.
Novel tests and inspection methods for textile reinforced composite tubes
W. Hufenbach,L. Kroll,M. Gude,A. Czulak
Journal of Achievements in Materials and Manufacturing Engineering , 2005,
Abstract: Purpose: This paper describes innovative lightweight applications of fiber and textile reinforced polymers in aircraft, automotive and chemical industry.Design/methodology/approach: This paper deals with modern test methods of braided composite tube specimens as basic elements of modern composites. The tubes subjected to strength tests under superposed compressive, tensile and internal pressure loadings, and tested by the acoustic emission method for damage detection.Findings: For the quality assessment and here, especially for the verification of fibre orientations after manufacture, the X-ray method is an advantageous inspection method. For the identification of fracture modes, after uni- and biaxial mechanical test under tensile, compressive and torque loads as well under inner pressure loading the computer tomography CT is used. The acoustic emission to assess for damage detection in braided composite pipes, and mechanical loading. Moreover, from the applied techniques the information concerned quality of a manufactured specimen, damage propagation and determination the types of damages can be obtained.Research limitations/implications: Those three methods assure very good and promising results having one limitation in case of volume of a tested sample, e.g in the CT device, an allowable diameter of an investigated tubular specimen amounts to 150mm.Practical implications: Use of the methods resulted in improved efficiency of test process and analysis of GFRP tubular specimens.Originality/value: The paper describes the new implicated test and inspection methods for textile reinforced composite tubes.
Optimisation of the rivet joints of the CFRP composite material and aluminium alloy
W. Hufenbach,L.A. Dobrzański,M. Gude,J. Konieczny
Journal of Achievements in Materials and Manufacturing Engineering , 2007,
Abstract: Purpose: The project included analysis of strain, cracking, and failure of riveted joints of plate elements madefrom the carbon-fibre-reinforced plastics (CFRP) and from the 6061 aluminium alloy.Design/methodology/approach: The modelled static tensile strength test carried out for the plates from CFRPand from the 6061 aluminium alloy joined with the steel rivet. Computer simulation was carried out with IDEASsoftware package employing the FEM.Findings: Simulations using the mesh with a bigger number of FEM elements do not yield better accuracy ofcalculations and do not improve convergence with the results of laboratory experiments. Only the calculationtime gets longer. Computer simulation has also show that the type of contacts employed between elementsaffects the results significantly.Research limitations/implications: For the composite materials, joints between materials and computersimulation examinations are planed.Practical implications: Results obtained for the mesh with 4 and 5 FEM elements are the closest to the resultsof laboratory experiments, which is confirmed by the strain plot. Simulations using the mesh with a biggernumber of FEM elements do not yield better accuracy of calculations and do not improve convergence with theresults of laboratory experiments. Only the calculation time gets longer. Computer simulation has show that thetype of contacts employed between elements affects the results significantly.Originality/value: The paper presents influence of fibre mesh closeness on convergence of the results with laboratorytests. Simulation results were collected and compared with the laboratory static tensile strength tests results.
Process Chain Modelling and Analysis for the High-Volume Production of Thermoplastic Composites with Embedded Piezoceramic Modules
W. Hufenbach,M. Gude,N. Modler,Th. Heber,A. Winkler,T. Weber
Smart Materials Research , 2013, DOI: 10.1155/2013/201631
Abstract: Active composite structures based on thermoplastic matrix systems are highly suited to applications in lightweight structures ready for series production. The integration of additional functional components such as material-embedded piezoceramic actuators and sensors and an electronic network facilitates the targeted control and manipulation of structural behaviour. The current delay in the widespread application of such adaptive structures is primarily attributable to a lack of appropriate manufacturing technologies. It is against this backdrop that this paper contributes to the development of a novel manufacturing process chain characterized by robustness and efficiency and based on hot-pressing techniques tailored to specific materials and actuators. Special consideration is given to detailed process chain modelling and analysis focusing on interactions between technical and technological aspects. The development of a continuous process chain by means of the analysis of parameter influences is described. In conclusion, the use of parameter manipulation to successfully realize a unique manufacturing line designed for the high-volume production of adaptive thermoplastic composite structures is demonstrated. 1. Introduction The increasing scarcity or resources around the world necessitates the development of high-tech products with a high level of sustainability. Function-integrative lightweight engineering in multimaterial design is a vital source of key technologies for various applications in this field. In recent years comfort and environmental criteria have become an increasingly important element of automotive, medical, and civil engineering applications. The superior specific mechanical properties, excellent design flexibility, and cost-efficient, reproducible manufacturing processes which characterize fibre-reinforced composites based on thermoplastic matrix systems enable them to fulfil these criteria. In particular, those characteristics make them highly suited to applications in lightweight structures ready for high-volume production. Moreover, the integration of additional functional components such as piezoceramic actuators or sensors into thermoplastic lightweight structures facilitates the manipulation of the dynamic and vibroacoustic behaviour of those structures [1–3]. In addition to quality monitoring, energy harvesting, and active vibration or noise control [4–8], a number of structural applications (e.g., in morphing structures and compliant mechanisms) are also possible [9–13]. State-of-the-art production of adaptive lightweight
Parametric investigation of acoustic radiation by a beam under load and actuator forces Параметрическое исследование акустического излучения балкой под нагрузкой и актуаторами типа силы ПАРАМЕТРИЧНЕ ДОСЛ ДЖЕННЯ АКУСТИЧНОГО ВИПРОМ НЮВАННЯ БАЛКОЮ П Д НАВАНТАЖЕННЯМ ТА АКТУАТОРАМИ ТИПУ СИЛИ
Alexander Zaporozhets,Vadim Tokarev,Werner Hufenbach,Olaf Taeger
Proceedings of National Aviation University , 2005,
Abstract: The objective of this paper is to investigate the parametric characteristics of oscillating beam using an analytical theory of beam vibration. Analytical investigation of the bending oscillations of a finite elastic beam is considered for criteria based on minimal acoustic radiation. The solution of the task is defined by solving of Helmholtz equation and inhomogeneous differential equation for beam bending vibration with harmonic time dependence. For calculation of the acoustic field a model of a plane piston, which is set in an infinite rigid baffle, is used. Исследованы параметрические характеристики колебаний балки с использованием аналитической теории вибрации балки. Аналитическое исследование изгибных колебаний эластичной балки конечных размеров рассмотрено для критерия, определяющего минимальное акустическое излучение. Решение задачи определено для уравнения Гельмгольца и неоднородного дифференциального уравнения гармонических изгибных колебаний балки. Для расчета акустического поля использована модель поршня, установленного на бесконечный экран. Досл джено параметричн характеристики коливань балки з використанням анал тично теор в брац балки. Анал тичне досл дження згинальних коливань еластично балки к нцевих розм р в розглянуто для критер ю, що визнача м н мальне акустичне випром нювання. Розв’язок задач визначено для р вняння Гельмгольца неоднор дного диференц йного р вняння гармон чних згинальних коливань балки. Для обчислення акустичного поля застосовано модель поршня, установленого на неск нченний екран.
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