@inproceedings{9568, abstract = {{A simple pre-stress estimate method of Langevin transducers is studied. The measurement setup consists of a capacitor, an impedance converter and a voltmeter. Based on the piezoelectric equation and the basic circuit theory, the mathematical expression between the pre-stress and the voltage across the capacitor is derived. The pre-stress level can then be calculated out of the measurement of the capacitor voltage. In order to evaluate the precision of this method, a force washer is used to measure the pre-stress of the Langevin transducer. The result shows the pre-stress level obtained from this method is 30-40\% higher than the pre-stress level measured by the force washer. This method is simple and can be used to estimate the pre-stress of various Langevin transducers. The precision of this method can be raised if d33 is identified under different pre-stress levels.}}, author = {{Bo, Fu and Ting, Li and Hemsel, Tobias}}, booktitle = {{Piezoelectricity, Acoustic Waves, and Device Applications, 2008. SPAWDA 2008. Symposium on}}, keywords = {{capacitors, impedance convertors, piezoelectric transducers, stress analysis, Langevin transducers, basic circuit theory, capacitor, impedance converter, piezoelectric equation, pre-stress estimating method, voltmeter, Capacitors, Educational institutions, Equations, Force measurement, Impedance measurement, Manufacturing, Mechatronics, Piezoelectric transducers, Voltage, Voltmeters, Langevin transducer, capacitor, piezoelectric element, pre-stress}}, pages = {{324--327}}, title = {{{A simple pre-stress estimating method of langevin transducers}}}, doi = {{10.1109/SPAWDA.2008.4775801}}, year = {{2008}}, } @article{9569, abstract = {{Ultrasonic hyperthermia and thermo-ablation are two promising alternatives for local overheating of deep-seated human tumours. After a short characterisation of the two techniques and the identification of the main parameters, results of an analytical theory of local heat up, cooling, and heat diffusion are presented. The theory is based on a spherical model for hyperthermia with a critical thermal dose and on a cylinder-symmetrical model for thermo-ablation with a critical temperature threshold for thermal toxicity and cell death through coagulative necrosis. Two representative hard ware concepts are discussed. The hyperthermia applicator consists of a MHz transducer, which rotates concentrically in a water filled capsule with acoustically transparent window, and radiates collimated or focussed ultrasound under 45$\,^{\circ}$ into a concentric target area of nearly spherical symmetry. The applicator for thermo-ablation is a MHz transducer which radiates high intensity focussed ultrasound (HIFU) into "cigar shaped" target areas at the focal zone. Typical therapy diagrams for both techniques are presented. They show therapeutic target volumes as functions of the therapy time with the peak temperature or the radiated acoustic power as parameters. These diagrams are discussed under consideration of power requirement, maximal sound intensity, and power efficiency at close to optimized frequency conditions.}}, author = {{Lierke, Ernst-Günter and Hemsel, Tobias}}, journal = {{Acta Acustica united with Acustica}}, number = {{3}}, pages = {{369--381}}, title = {{{Local Ultrasonic Hyperthermia and Thermo-ablation: A Description and Theoretical Evaluation of Two Alternative Concepts for the Heat Therapy of Tumours}}}, doi = {{10.3813/AAA.918044}}, volume = {{94}}, year = {{2008}}, } @inproceedings{9570, abstract = {{EN: Although the use of new actuator technologies is quite enthusiastic, the realization of innovative systems based on these principles fails because of doubts in dependability. Until now, new working principles for actuators have not been systematically investigated in the means of dependability. Therefore we developed a proceeding for a dependability-oriented evaluation of technologies. This is shown in the case of shape memory alloy actuators. DE: Die Realisierung von Systemen mittels innovativer Aktortechnologien scheitert oftmals an der Skepsis gegenüber der Verlässlichkeit (Vertrauen in die zuverlässige und sichere Funktionalität der Technologie). Diese liegt darin begründet, dass neue Aktortechnologien bzw. die Integration von innovativen physikalischen Wirkprinzipen innerhalb neuer Aktorkonzepte bisher noch nicht systematisch im Kontext der Verlässlichkeit untersucht werden. Daher haben wir ein Vorgehen zur verlässlichkeitsorientierten Technologiebewertung entwickelt. Neben der detaillierten Darstellung des Vorgehensmodells wird es exemplarisch anhand von Formgedächtnislegierungen zur Entwicklung innovativer Antriebslösungen angewendet.}}, author = {{Müller, Thomas and Schiedeck, Florian and Hemsel, Tobias}}, booktitle = {{2. Tagung des DVM -- Arbeitskreis Zuverlässigkeit mechatronischer und adaptronischer Systeme: Absicherung der Systemzuverlässigkeit, Koblenz}}, keywords = {{EN: Dependability, Reliability, Evaluation of Technology, Actuators, Shape Memory Alloys DE: Verl{\}}, title = {{{Verlässlichkeitorientierte Technologiebewertung innovativer Aktortechnologien am Beispiel von Formgedächtnislegierungen}}}, year = {{2008}}, } @article{9571, abstract = {{Several positioning tasks demand translatory drive instead of rotary motion. To achieve drives that are capable, e.g., to drive the sunroof of a car or to lift a car's window, multiple miniaturized motors can be combined. But in this case many other questions arise: The electromechanical behavior of the individual motors differs slightly, the motor characteristics are strongly dependent on the driving parameters and the driven load, many applications need some extra power for special cases like overcoming higher forces periodically. Thus, the bundle of motors has to act well-organized and at last controlled to get an optimized drive that is not oversized and costly.}}, author = {{Mracek, Maik and Hemsel, Tobias and Sattel, Thomas and Vasiljev, Piotr and Wallaschek, Jörg}}, issn = {{1385-3449}}, journal = {{Journal of Electroceramics}}, keywords = {{Ultrasonic linear motor, High power, Control, Modeling, Characteristics}}, number = {{3-4}}, pages = {{153--158}}, publisher = {{Springer US}}, title = {{{Driving concepts for bundled ultrasonic linear motors}}}, doi = {{10.1007/s10832-007-9123-5}}, volume = {{20}}, year = {{2008}}, } @inproceedings{9573, abstract = {{Integrating dependability in self-optimizing systems is a challenging task. Self-optimizing systems incorporate on the one hand the opportunity to apply novel solutions to complex mechatronic systems, but on the other hand constitute a possible risk because of non-determined behavior. The dependability concept in this paper covers both aspects: Increasing safety with selfoptimization and minimizing the risk of self-optimization. This dependability concept is combined with the self-optimization process of the active guidance module which is currently under development at the Collaborative Research Center 614 at the University of Paderborn.}}, author = {{Sondermann-Wölke, Christoph and Geisler, Jens and Müler, Thomas and Trächtler, Ansgar and Böcker, Joachim}}, booktitle = {{ASME 2008 -- International Design Engineering Technical Conferences \& Computers and Information in Engineering Conference (IDETC/CIE)}}, title = {{{The active guidance module of a rail-bound vehicle as an application for the dependability oriented design in self-optimizing systems}}}, year = {{2008}}, } @article{9574, abstract = {{For devices having non-linear contact, load plays a fundamental role. Variations in the characteristics of the load cause change in eigenfrequency and amplitude of the vibration. In most technical applications, this unwanted behaviour is cancelled by the use of control algorithms. However, multiple applications, like bond quality monitoring or chemical and pressure sensors, have found that the load may be characterised by interpreting the change in characteristics of a resonant vibrating device used as a sensor. Surgical resection of tumours is a very difficult task. After localising the tumour by the use of imaging techniques, the resection demands the surgeon to decide where and what to resect based on visual and tactile differentiation of tumour and healthy tissue. Exactness of this process could be enhanced if we can provide the surgeon with a device capable of evaluating mechanical characteristics of the tissue much more accurately than the surgeon himself can do. As the mechanical characteristics of tumour and healthy tissue differ but slightly, the task is to design a system with high sensitivity. Therefore, we have developed a resonant actuator-sensor that allows the differentiation among distinct media that have similar mechanical characteristics to tumour and healthy tissue using a piezoelectric bimorph. The design is based on the detection and evaluation of frequency shift and amplitude variation of the fundamental and higher harmonics using one layer for the resonant excitation of vibration and the other one as the sensing element.}}, author = {{Stroop, Ralf and Uribe, David Oliva and Martinez, Melisa Orta and Brökelmann, Michael and Hemsel, Tobias and Wallaschek, Jörg}}, issn = {{1385-3449}}, journal = {{Journal of Electroceramics}}, keywords = {{Piezo ceramics, Bimorph, Tactile sensor, Tumour tissue}}, number = {{3-4}}, pages = {{237--241}}, publisher = {{Springer US}}, title = {{{Tactile tissue characterisation by piezoelectric systems}}}, doi = {{10.1007/s10832-007-9183-6}}, volume = {{20}}, year = {{2008}}, } @article{9575, abstract = {{Many ultrasonic processes are based on the mechanical contact of oscillating parts. Within ultrasonic machining (drilling, milling, grinding) micro impacts lead to abrasion at the processed workpiece and hopefully do not damage the tool. In ultrasonic motors ideally neither part gets worn. Thus the appropriate design of contact partners as well as their kinematics is a substantial task during the development of such devices. A first step to optimize contact mechanics is to understand their behavior and dependencies on parameter variations, such as vibration amplitude and pre-stress of the impacting parts. For a detailed understanding models validated with convincing experimental data from measurements are absolutely essential. This paper focuses on simple vibro-impact experiments which can be used as benchmark data for future models. The setup of the experiment and first experimental investigations are described in detail.}}, author = {{Twiefel, Jens and Potthast, Christian and Mracek, Maik and Hemsel, Tobias and Sattel, Thomas and Wallaschek, Jörg}}, issn = {{1385-3449}}, journal = {{Journal of Electroceramics}}, keywords = {{Contact measurements, Vibro-impact, Ultrasonic application}}, number = {{3-4}}, pages = {{209--214}}, publisher = {{Springer US}}, title = {{{Fundamental experiments as benchmark problems for modeling ultrasonic micro-impact processes}}}, doi = {{10.1007/s10832-007-9169-4}}, volume = {{20}}, year = {{2008}}, } @inproceedings{9576, abstract = {{In neurosurgery, delineation of tumor boundaries during resection of brain tumors is of substantial relevance. During operation distinction between tumor and healthy tissue rely on the abilities of the surgeon based on visual and tactile differentiation. In this paper a high sensitivity actuator-sensor system using a piezoelectric bimorph is presented. Frequency shift and transfer function of the bimorphpsilas voltages are detected and evaluated. Sensorpsilas sensitivity is evaluated using two frequency controls strategies: A phase-locked loop (PLL) and a self-oscillating circuit. Results of measurements conducted on gel-phantoms are presented and discussed.}}, author = {{Uribe, David Oliva and Stroop, Ralf and Hemsel, Tobias and Wallaschek, Jörg}}, booktitle = {{Frequency Control Symposium, 2008 IEEE International}}, issn = {{1075-6787}}, keywords = {{biomedical measurement, brain, cancer, neurophysiology, phantoms, phase locked loops, piezoelectric actuators, surgery, tactile sensors, transfer functions, tumours, PLL, biomedical tissue differentiation system, brain tumor resection, frequency control, frequency shift, gel-phantom, high sensitivity actuator-sensor system, neurosurgery, phase-locked loop, piezoelectric actuators, piezoelectric bimorph, self-oscillating circuit, sensor sensitivity, tactile differentiation, tactile sensor system, transfer function, tumor boundary, visual differentiation, Biomedical measurements, Circuits, Frequency control, Neoplasms, Neurosurgery, Phase locked loops, Piezoelectric actuators, Surges, Transfer functions, Voltage}}, pages = {{91--94}}, title = {{{Development of a biomedical tissue differentiation system using piezoelectric actuators}}}, doi = {{10.1109/FREQ.2008.4622963}}, year = {{2008}}, } @inproceedings{15954, author = {{Tröster, Thomas and Howe, C. and Müller, M. and Rostek, W.}}, location = {{Wiesbaden}}, title = {{{Development status and market potential of hot formed ballistic steels}}}, year = {{2008}}, } @article{15955, abstract = {{The present paper reports on the effect of texture on the cyclic stress-strain response (CSSR) and the fatigue life of ultrafine-grained (UFG) interstitial-free (IF) steel. Tests in the lowcycle fatigue (LCF) regime were conducted on material that was processed by the equal channel angular extrusion (ECAE) technique along the so called “efficient” route 8E. This route has been shown to result in a homogeneous microstructure with a high fraction of high angle grain boundaries (HAGBs), which are beneficial for a stable CSSR. In addition, the evolution of the microstructure was characterized by means of electron optical techniques, including electron backscattered diffraction, and by X-Ray diffractometry. It was found that the initial texture of specimens cut from the ECAE billet along different orientations with respect to the extrusion direction (ED) has a substantial effect on the CSSR of the UFG IF steel. Furthermore, microscopy results indicated the notable influence of the last ECAE processing step on the evolution of damage in the material.}}, author = {{Niendorf, Thomas and Marten, Thorsten and Maier, Hans J. and Karaman, Ibrahim}}, issn = {{1662-9752}}, journal = {{Materials Science Forum}}, pages = {{864--869}}, title = {{{The Effect of Texture on the Fatigue Properties of Ultrafine-Grained Interstitial-Free Steel}}}, doi = {{10.4028/www.scientific.net/msf.584-586.864}}, volume = {{584-586}}, year = {{2008}}, } @misc{9572, author = {{Rischmueller, Volker and Wallaschek, Jörg and Froehlich, Peter and Haussecker, Walter and Rieger, Vincent and Twiefel, Jens and Guenther, Dirk and Hemsel, Tobias}}, title = {{{Patent EP2156480: Piezoelektrische Antriebsvorrichtung / Piezoelectric Drive Unit}}}, year = {{2008}}, } @inproceedings{33878, author = {{Tröster, Thomas and Rostek, W. and Böke, J. and Erhardt, R.}}, booktitle = {{Ein wesentlicher Beitrag zur Klimadebatte}}, location = {{Berlin}}, title = {{{Einsatz von Simulationswerkzeugen in der Entwicklungskette von ultrahochfesten warmgeformten Strukturkomponenten im Fahrzeugleichtbau}}}, volume = {{675}}, year = {{2008}}, } @inproceedings{35275, author = {{Magyar, Balázs and Horák, P}}, isbn = {{978-963-420-947-8}}, pages = {{G--2008--A--12}}, title = {{{Geometrical modeling and investigation of the contact relations of spatial gears}}}, year = {{2008}}, } @article{35283, author = {{Magyar, Balázs and Horák, P}}, journal = {{GÉP}}, number = {{4}}, pages = {{28--30}}, title = {{{Geometrische Modellierung und Untersuchung der Berührungsverhältnisse bei den Räumlichenverzahnungen}}}, volume = {{LIX}}, year = {{2008}}, } @article{35282, author = {{Magyar, Balázs and Horák, P}}, issn = {{0016-8572}}, journal = {{GÉP}}, number = {{10-11}}, pages = {{44--47}}, title = {{{Modellierung der Berührungsverhältnisse von Hohflanken-Schneckenradsätzen}}}, volume = {{LIX}}, year = {{2008}}, } @article{26267, author = {{Mahnken, Rolf}}, issn = {{1537-6494}}, journal = {{Mechanics of Advanced Materials and Structures}}, pages = {{514--527}}, title = {{{Finite Deformation Elasto-Plasticity for Simulation of Strength Difference in Adhesive Materials with an Algorithm in Principal Directions}}}, doi = {{10.1080/15376490802142718}}, year = {{2008}}, } @article{26258, author = {{Sauerland, Kim-Henning and Gockel, Franz-Barthold and Mahnken, Rolf and Ferber, Ferdinand}}, issn = {{1058-9759}}, journal = {{Nondestructive Testing and Evaluation}}, pages = {{3--18}}, title = {{{Damage analysis under thermal shock loading using eddy current sensors}}}, doi = {{10.1080/10589750802195451}}, year = {{2008}}, } @article{26274, author = {{Mahnken, Rolf and Shaban, A. and Potente, H. and Wilke, L.}}, issn = {{0020-7683}}, journal = {{International Journal of Solids and Structures}}, pages = {{4615--4628}}, title = {{{Thermoviscoplastic modelling of asymmetric effects for polymers at large strains}}}, doi = {{10.1016/j.ijsolstr.2008.03.033}}, year = {{2008}}, } @article{26261, author = {{Mahnken, Rolf and Schneidt, Andreas and Antretter, Thomas}}, issn = {{0749-6419}}, journal = {{International Journal of Plasticity}}, pages = {{183--204}}, title = {{{Macro modelling and homogenization for transformation induced plasticity of a low-alloy steel}}}, doi = {{10.1016/j.ijplas.2008.03.005}}, year = {{2008}}, } @article{23267, author = {{Koke, Isabel and Müller, Wolfgang H. and Ferber, Ferdinand and Mahnken, Rolf and Funke, Herbert}}, journal = {{Composites Science and Technology}}, number = {{Issue 5}}, pages = {{1156--1164}}, title = {{{Measuring mechanical parameters in glass fiber-reinforced composites: Standard evaluation techniques enhanced by photogrammetry}}}, volume = {{68}}, year = {{2008}}, }