@article{21706, abstract = {{Additive Manufacturing offers a high potential in the aerospace due to its freedom of design and the ability to manufacture complex and lightweight parts. Profound changings of the existing processes can be expected for the area of Maintenance, Repair and Overhaul (MRO) as well. It is described with the help of scenarios which chances result from the integration of this technology while different applications are considered. It starts with the implementation of AM as another manufacturing technology for the repair of spare parts. The precision reduces the effort for post-processing in comparison to the conventional manufacturing methods such as the build-up welding. If an unexpected part breakdown occurs and the aircraft has to stay on ground, there are high demands on the logistics to deliver the required spare parts from the warehouse as fast as possible. The storage of spare parts causes extremely high costs and can be considerably reduced with the help of Additive Manufacturing. Distributed generative manufacturing centers can lead to a far-reaching restructuring of the existing processes where the required spare part is manufactured locally on demand. The resulting opportunities and risks for the involved market actors are shown within the presentation. It is described how MRO service providers and OEMs are affected by that and which changes of today’s processes are necessary to implement the presented scenarios.}}, author = {{Deppe, G. and Koch, R.}}, journal = {{Rtejournal}}, number = {{11}}, title = {{{Exploring the influence of an Additive Manufacturing integration on future MRO processes in aeronautics}}}, doi = {{https://www.rtejournal.de/ausgabe11/3958}}, volume = {{2014}}, year = {{2014}}, } @inproceedings{22018, abstract = {{Fused Deposition Modeling (FDM) parts are prone to process-related rough and wavy surfaces with stair-stepping effects whenever the parts produced have sloped or rounded geometries. These stair-stepping effects can be reduced by using a smaller slice height, but complete elimination is not possible. In this paper, FDM parts manufactured with the material ABS-M30 are finished using mass finishing methods. The mass finishing is done with a trough vibrator, which is comparatively gentle to the parts in comparison to other mass finishing technologies. The analysis discusses the surface-smoothing effect of finishing time and intensity on various part sizes and build orientations. In addition, the dimensional accuracy of the parts after the finishing process is examined.}}, author = {{Fischer, M. and Schöppner, Volker}}, booktitle = {{25th Annual International Solid Freeform Fabrication Symposium}}, pages = {{923--934}}, title = {{{Finishing of ABS-M30 Parts Manufactured with Fused Deposition Modeling with Focus on Dimensional Accuracy}}}, doi = {{http://utw10945.utweb.utexas.edu/sites/default/files/2014-073-Fischer.pdf}}, volume = {{25}}, year = {{2014}}, } @inproceedings{9868, abstract = {{In order to increase mechanical strength, heat dissipation and ampacity and to decrease failure through fatigue fracture, wedge copper wire bonding is being introduced as a standard interconnection method for mass production. To achieve the same process stability when using copper wire instead of aluminum wire a profound understanding of the bonding process is needed. Due to the higher hardness of copper compared to aluminum wire it is more difficult to approach the surfaces of wire and substrate to a level where van der Waals forces are able to arise between atoms. Also, enough friction energy referred to the total contact area has to be generated to activate the surfaces. Therefore, a friction model is used to simulate the joining process. This model calculates the resulting energy of partial areas in the contact surface and provides information about the adhesion process of each area. The focus here is on the arising of micro joints in the contact area depending on the location in the contact and time. To validate the model, different touchdown forces are used to vary the initial contact areas of wire and substrate. Additionally, a piezoelectric tri-axial force sensor is built up to identify the known phases of pre-deforming, cleaning, adhering and diffusing for the real bonding process to map with the model. Test substrates as DBC and copper plate are used to show the different formations of a wedge bond connection due to hardness and reaction propensity. The experiments were done by using 500 $\mu$m copper wire and a standard V-groove tool.}}, author = {{Althoff, Simon and Neuhaus, Jan and Hemsel, Tobias and Sextro, Walter}}, booktitle = {{Electronic Components and Technology Conference (ECTC), 2014 IEEE 64th}}, keywords = {{adhesion, circuit reliability, deformation, diffusion, fatigue cracks, friction, interconnections, lead bonding, van der Waals forces, Cu, adhering process, adhesion process, ampacity improvement, bond quality improvement, cleaning process, diffusing process, fatigue fracture failure, friction energy, friction model, heat dissipation, mechanical strength, piezoelectric triaxial force sensor, predeforming process, size 500 mum, total contact area, van der Waals forces, wedge copper wire bonding, Bonding, Copper, Finite element analysis, Force, Friction, Substrates, Wires}}, pages = {{1549--1555}}, title = {{{Improving the bond quality of copper wire bonds using a friction model approach}}}, doi = {{10.1109/ECTC.2014.6897500}}, year = {{2014}}, } @inproceedings{9869, abstract = {{Cavitation monitoring is desired to optimize the sonication for diverse sonochemical processes and to detect changes or malfunctions during operation. In situ cavitation measurements can be carried out by detection of the acoustic emissions of cavitation bubbles by sensors in the liquid. However, in harsh environments sensors might not be applicable. Thus, the impact of cavitation on the electrical signals of a piezoelectric transducer has been analyzed as alternative method to measure the threshold, strength and type of cavitation. The applicability has been tested in three different setups to evaluate the general- izability of extracted indicators. In all setups indicators for the cavitation thresholds could be derived from the current signal. In two setups features showed two thresholds that may be linked to the types of cavitation. However, only one feature derived from the current signal in one particular setup correlated to the strength of cavitation. Cavitation detection based on the current signal of the transducer is a useful method to detect cavitation in harsh environments and without perturbing the sound field. Once appli- cable indicators have been identified, they may easily be tracked during the process. However, for more detailed studies about the cavitation activity and its spatial distribution, measurements with in situ sensors are recommended.}}, author = {{Bornmann, Peter and Hemsel, Tobias and Sextro, Walter and Memoli, Gianluca and Hodnett, Mark and Zeqiri, Bajram}}, booktitle = {{2014 IEEE International Ultrasonics Symposium Proceedings}}, isbn = {{9781479970490}}, pages = {{663--666}}, title = {{{Self-Sensing Ultrasound Transducer for Cavitation Detection}}}, doi = {{10.1109/ULTSYM.2014.0163}}, year = {{2014}}, } @inproceedings{9870, abstract = {{Nowadays wire bonding is a widely-used technology for interconnecting chips in the packaging industry. Thereby, it is known that the bond quality massively depends upon the microstructure prevailing in the bond and consequently the materials used as well as the bonding parameters. However the actually used materials such as aluminum and gold are either characterized by comparibly poor conductivity or high costs, respectively. Due to its outstanding properties copper is a more attractive candidate. Still, a thorough investigation on the interrelationship between the material combinations, the processing parameters and the resulting microstructure for copper and aluminum wire bonding was not carried out yet. Depending on the aforementioned factors the microstructural evolution can be completely different during the bonding process. Therefore, this study focuses on the microstructural evolution of heavy copper and heavy aluminum wires bonded on copper substrates. The evolution of the wire microstructure as well as the wire-substrate-interface was investigated by scanning electron microscope in combination with electron backscatter diffraction and microhardness measurements. Various samples were extracted at different points of the bonding process, namely the as-received condition, after touchdown and after completed bonding. The results of the aluminum and copper wires were compared to each other in both longitudinal and transversal direction. It was found, that the two wire materials were completely different in the as-received condition regarding the grain size, the grain morphology, the texture and the microhardness. After touchdown the microstructure did not show significant changes in both materials, yet a strain-hardening was observed in the copper wire resulting from the touchdown force. When the bonding process was completed a different microstructure could be observed in both the wire as well as the layer for the materials investigated. Furthermore, a destinctive increase in the wire hardness could be found in case of copper, which was not observed for the aluminum wire. The ramifications between the two wire materials presented in this work will be discussed with the objective of optimizing the quality of the bonds.}}, author = {{Eacock , Florian and Schaper, Mirko and Althoff, Simon and Unger, Andreas and Eichwald, Paul and Hengsbach, Florian and Zinn, Carolin and Holzweissig, Martin Joachim and Guth, Karsten}}, booktitle = {{Proceedings of the 47th International Symposium on Microelectronics}}, keywords = {{Bonding, Copper, Microstructure evolution}}, title = {{{Microstructural investigations of aluminum and copper wire bonds}}}, doi = {{10.4071/isom-THP32}}, year = {{2014}}, } @inproceedings{9871, abstract = {{Wire bonding is the most common technology for connecting electronic components. Due to their efficiency bond interconnections made of copper wire are used for example in the aerospace and medical technology as well as in the fields of renewable energies. One of the main cost factors in the manufacturing process is the consumables like bonding tools. The technological transition to copper as wire material causes significant wear on the millimeter large effective contact area of the bonding tool. This wear leads to a loss by a factor of 30 of the number of reliable interconnections which can be produced by a single tool. To reduce setting-up time in the production and minimizing costs, an enlarged bonding tool lifetime is desirable. Consequently a better understanding of wear and recognition of wear pattern is required. Therefore, the paper presents an analyzing method of the tool topography change of a heavy wire bonding tool by using a confocal microscope. Furthermore, the paper discusses the identification of the main wear indicators by the help of the named topography change for different bond parameters, like ultrasonic power and tool geometry. Reference topography has been carried out by choosing typical parameters of the production line. To judge whether the quality requirement of the bond connections made by a single tool cannot be fulfilled shear test of the source bond have been carried out after a defined number of produced bond connections. Main steps of analysis: (I)Topography of the tool surface is sampled after a defined number of bonds by means of a confocal microscope to detect the wear progress.(II)The recorded data is filtered using Matlab. So, measurement errors can be eliminated and the topography can be overlaid more easy to identify differences between diverse tools or differences in wear stages of the same tool.(III)The subsequent discretization of the topography into sub volumes allows to (IV)describe the loss of volume depending on the position in the groove. Thereby, intermediate status of wear of one tool can be used to obtain a persistent description of the topography change over the number of produced bonds by interpolating the confocal data. Afterwards the persistent change of the groove flank has been analyzed for the named test series to identify the main wear indicators and their effect on shear forces. All worn tools show dominant areas for volume loss especially for plastic deformation and accordingly abrasion. These wear mechanism can be referred to the change of main parts of the groove geometry like the rounding of the front and back radius. The most volume loss was identified in the upper part of the tool flanks or rather at the transition from the groove flank to the front or back radius. Furthermore the observation of the center of the groove flank shows just a little change in volume. All in all, the identification of the wear indicators will be discussed with the objective of increasing the tool lifetime by optimizing the tool geometry without losses in bond quality and reliability.}}, author = {{Eichwald, Paul and Sextro, Walter and Althof, Simon and Eacock, Florian and Unger, Andreas and Meyer, Tobias and Guth, Karsten}}, booktitle = {{Proceedings of the 47th International Symposium on Microelectronics}}, keywords = {{wedge/wedge bonding, copper wire, tool wear}}, pages = {{856--861}}, title = {{{Analysis Method of Tool Topography Change and Identification of Wear Indicators for Heavy Copper Wire Wedge Bonding}}}, doi = {{10.4071/isom-THP34}}, year = {{2014}}, } @book{9873, abstract = {{Intelligent technical systems, which combine mechanical, electrical and software engineering with methods from control engineering and advanced mathematics, go far beyond the state of the art in mechatronics and open up fascinating perspectives. Among these systems are so-called self-optimizing systems, which are able to adapt their behavior autonomously and flexibly to changing operating conditions. The Collaborative Research Center 614 "Self-optimizing concepts and structures in mechanical engineering" pursued the long-term aim to enable others to develop dependable self-optimizing systems. Assuring their dependability poses new challenges. However, self-optimization also offers the possibility to adapt the system's behavior to improve dependability during operation. The aim of this book is to provide methods and techniques to master the challenges and to exploit the possibilities given by self-optimization. The reader will be able to develop self-optimizing systems that fulfill and surpass today’s dependability requirements easily. This book is directed to researchers and practitioners alike. It gives a brief introduction to the holistic development approach for self-optimizing mechatronic systems and the steps required to assure a dependable product design starting with the very early conceptual design phase. A guideline to select suitable methods for each step and the methods themselves are included. Each method is individually introduced, many examples and full references are given.}}, author = {{Gausemeier, Jürgen and Josef Rammig, Franz and Schäfer, Wilhelm and Sextro, Walter}}, publisher = {{Springer Berlin Heidelberg}}, title = {{{Dependability of Self-Optimizing Mechatronic Systems}}}, volume = {{Lecture Notes in Mechanical Engineering}}, year = {{2014}}, } @article{9874, author = {{Hemsel, Tobias and Bornmann, Peter and Morita, Takeshi and Sondermann-Wölke, Christoph and Sextro, Walter}}, issn = {{0939-1533}}, journal = {{Archive of Applied Mechanics}}, keywords = {{Reliability, Ultrasonic power transducers, FMEA}}, pages = {{1--7}}, publisher = {{Springer Berlin Heidelberg}}, title = {{{Reliability analysis of ultrasonic power transducers}}}, doi = {{10.1007/s00419-014-0965-4}}, year = {{2014}}, } @article{9876, abstract = {{Piezoelectric inertia motors use the inertia of a body to drive it by means of a friction contact in a series of small steps. It has been shown previously in theoretical investigations that higher velocities and smoother movements can be obtained if these steps do not contain phases of stiction (''stick-slip`` operation), but use sliding friction only (''slip-slip`` operation). One very promising driving option for such motors is the superposition of multiple sinusoidal signals or harmonics. In this contribution, the theoretical results are validated experimentally. In this context, a quick and reliable identification process for parameters describing the friction contact is proposed. Additionally, the force generation potential of inertia motors is investigated theoretically and experimentally. The experimental results confirm the theoretical result that for a given maximum frequency, a signal with a high fundamental frequency and consisting of two superposed sine waves leads to the highest velocity and the smoothest motion, while the maximum motor force is obtained with signals containing more harmonics. These results are of fundamental importance for the further development of high-velocity piezoelectric inertia motors.}}, author = {{Hunstig, Matthias and Hemsel, Tobias and Sextro, Walter}}, issn = {{0939-1533}}, journal = {{Archive of Applied Mechanics}}, keywords = {{Inertia motor, High velocity, Stick-slip motor, Slip-slip operation, Friction parameter identification}}, pages = {{1--9}}, publisher = {{Springer Berlin Heidelberg}}, title = {{{High-velocity operation of piezoelectric inertia motors: experimental validation}}}, doi = {{10.1007/s00419-014-0940-0}}, year = {{2014}}, } @article{9878, abstract = {{(K,Na)NbO3 ceramics have attracted much attention as lead-free piezoelectric materials with high piezoelectric properties. High-quality (K,Na)NbO3 ceramics can be sintered using KNbO3 and NaNbO3 powders synthesized by a hydrothermal method. In this study, to enhance the quality factor of the ceramics, high-power ultrasonic irradiation was employed during the hydrothermal method, which led to a reduction in the particle size of the resultant powders.}}, author = {{Isobe, G. and Maeda, Takafumi and Bornmann, Peter and Hemsel, Tobias and Morita, Takeshi}}, issn = {{0885-3010}}, journal = {{Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on}}, keywords = {{Q-factor, ceramics, crystal growth from solution, particle size, piezoelectric materials, potassium compounds, powders, sintering, sodium compounds, ultrasonic effects, (K0.48Na0.52)NbO3, KNbO3 powders, NaNbO3 powders, high-power ultrasonic irradiation, lead-free piezoelectric materials, lead-free piezoelectric powders, particle size reduction, piezoelectric properties, quality factor, sintered (K0.48Na0.52)NbO3 ceramics, sintering, ultrasonic-assisted hydrothermal method, Acoustics, Ceramics, Lead, Piezoelectric materials, Powders, Radiation effects, Transducers}}, number = {{2}}, pages = {{225--230}}, title = {{{Synthesis of lead-free piezoelectric powders by ultrasonic-assisted hydrothermal method and properties of sintered (K0.48Na0.52)NBO3 ceramics}}}, doi = {{10.1109/TUFFC.2014.6722608}}, volume = {{61}}, year = {{2014}}, } @inproceedings{9879, abstract = {{Application of prognostics and health management (PHM) in the field of Proton Exchange Membrane (PEM) fuel cells is emerging as an important tool in increasing the reliability and availability of these systems. Though a lot of work is currently being conducted to develop PHM systems for fuel cells, various challenges have been encountered including the self-healing effect after characterization as well as accelerated degradation due to dynamic loading, all which make RUL predictions a difficult task. In this study, a prognostic approach based on adaptive particle filter algorithm is proposed. The novelty of the proposed method lies in the introduction of a self-healing factor after each characterization and the adaption of the degradation model parameters to fit to the changing degradation trend. An ensemble of five different state models based on weighted mean is then developed. The results show that the method is effective in estimating the remaining useful life of PEM fuel cells, with majority of the predictions falling within 5\% error. The method was employed in the IEEE 2014 PHM Data Challenge and led to our team emerging the winner of the RUL category of the challenge.}}, author = {{Kimotho, James Kuria and Meyer, Tobias and Sextro, Walter}}, booktitle = {{Prognostics and Health Management (PHM), 2014 IEEE Conference on}}, keywords = {{ageing, particle filtering (numerical methods), proton exchange membrane fuel cells, remaining life assessment, PEM fuel cell prognostics, PHM, RUL predictions, accelerated degradation, adaptive particle filter algorithm, dynamic loading, model parameter adaptation, prognostics and health management, proton exchange membrane fuel cells, remaining useful life estimation, self-healing effect, Adaptation models, Data models, Degradation, Estimation, Fuel cells, Mathematical model, Prognostics and health management}}, pages = {{1--6}}, title = {{{PEM fuel cell prognostics using particle filter with model parameter adaptation}}}, doi = {{10.1109/ICPHM.2014.7036406}}, year = {{2014}}, } @inproceedings{9880, abstract = {{With the paradigm shift towards prognostic and health management (PHM) of machinery, there is need for reliable PHM methodologies with narrow error bounds to allow maintenance engineers take decisive maintenance actions based on the prognostic results. Prognostics is mainly concerned with the estimation of the remaining useful life (RUL) or time to failure (TTF). The accuracy of PHM methods is usually a function of the features extracted from the raw data obtained from sensors. In cases where the extracted features do not display clear degradation trends, for instance highly loaded bearings, the accuracy of the state of the art PHM methods is significantly affected. The data which lacks clear degradation trend is referred to as non-trending data. This study presents a method for extracting degradation trends from non-trending condition monitoring data for RUL estimation. The raw signals are first filtered using a discrete wavelet transform (DWT) denoising filter to remove noise from the acquired signals. Time domain, frequency domain and time-frequency domain features are then extracted from the filtered signals. An autoregressive model is then applied to the extracted features to identify the degradation trends. Features representing the maximum health information are then selected based on a performance evaluation criteria using extreme learning machine (ELM) algorithm. The selected features can then be used as inputs in a prognostic algorithm. The feasibility of the method is demonstrated using experimental bearing vibration data. The performance of the method is evaluated on the accuracy of RUL estimation and the results show that the method can be used to accurately estimate RUL with a maximum error of 10\%.}}, author = {{Kimotho, James Kuria and Sextro, Walter}}, booktitle = {{Proceedings of the Second European Conference of the Prognostics and Health Management Society 2014}}, keywords = {{autoregressive model ELM feature extraction feature selection non-trending Remaining useful Life}}, title = {{{An approach for feature extraction and selection from non-trending data for machinery prognosis}}}, volume = {{5}}, year = {{2014}}, } @article{9881, abstract = {{The increasing demand for high reliability, safety and availability of technical systems calls for innovative maintenance strategies. The use of prognostic health management (PHM) approach where maintenance action is taken based on current and future health state of a component or system is rapidly gaining popularity in the maintenance industry. Multiclass support vector machines (MC-SVM) has been identified as a promising algorithm in PHM applications due to its high classification accuracy. However, it requires parameter tuning for each application, with the objective of minimizing the classification error. This is a single objective optimization problem which requires the use of optimization algorithms that are capable of exhaustively searching for the global optimum parameters. This work proposes the use of hybrid differential evolution (DE) and particle swarm optimization (PSO) in optimally tuning the MC-SVM parameters. DE identifies the search limit of the parameters while PSO finds the global optimum within the search limit. The feasibility of the approach is verified using bearing run-to-failure data and the results show that the proposed method significantly increases health state classification accuracy.}}, author = {{Kimotho, James Kuria and Sextro, Walter}}, issn = {{1617-7061}}, journal = {{PAMM}}, number = {{1}}, pages = {{815--816}}, publisher = {{WILEY-VCH Verlag}}, title = {{{Optimal Parameter Tuning for Multiclass Support Vector Machines in Machinery Health State Estimation}}}, doi = {{10.1002/pamm.201410388}}, volume = {{14}}, year = {{2014}}, } @article{9882, abstract = {{An automotive suspension system represents one of the most complex and important systems in a passenger vehicle, which has to ensure a robust and optimized contact between the wheels and the road at any time. For improving a suspension system it is important to take an investigative look at the interaction between suspension, tire and road dynamics. Thus a part of a study into aspects of suspension modeling on multi-body simulations of rear multi-link suspension system dynamics with focus on the tire footprint area is presented in this work.}}, author = {{Kohl, Sergej and Sextro, Walter and Zuber, Armin}}, issn = {{1617-7061}}, journal = {{PAMM}}, number = {{1}}, pages = {{65--66}}, publisher = {{WILEY-VCH Verlag}}, title = {{{Tire footprint analysis depending on the elastokinematics of a multi-link suspension system using multi-body dynamics simulation}}}, doi = {{10.1002/pamm.201410020}}, volume = {{14}}, year = {{2014}}, } @inbook{9883, author = {{Meyer, Tobias and Priesterjahn, Claudia and Sextro, Walter}}, booktitle = {{Dependability of Self-Optimizing Mechatronic Systems}}, editor = {{Gausemeier, Jürgen and Josef Rammig, Franz and Schäfer, Wilhelm and Sextro, Walter}}, isbn = {{978-3-642-53741-7}}, pages = {{189--190}}, publisher = {{Springer Berlin Heidelberg}}, title = {{{Conclusion and Outlook}}}, doi = {{10.1007/978-3-642-53742-4_5}}, year = {{2014}}, } @inproceedings{9884, abstract = {{So-called reliability adaptive systems are able to adapt their system behavior based on the current reliability of the system. This allows them to react to changed operating conditions or faults within the system that change the degradation behavior. To implement such reliability adaptation, self-optimization can be used. A self-optimizing system pursues objectives, of which the priorities can be changed at runtime, in turn changing the system behavior. When including system reliability as an objective of the system, it becomes possible to change the system based on the current reliability as well. This capability can be used to control the reliability of the system throughout its operation period in order to achieve a pre-defined or user-selectable system lifetime. This way, optimal planning of maintenance intervals is possible while also using the system capabilities to their full extent. Our proposed control system makes it possible to react to changed degradation behavior by selecting objectives of the self-optimizing system and in turn changing the operating parameters in a closed loop. A two-stage controller is designed which is used to select the currently required priorities of the objectives in order to fulfill the desired usable lifetime. Investigations using a model of an automotive clutch system serve to demonstrate the feasibility of our controller. It is shown that the desired lifetime can be achieved reliably.}}, author = {{Meyer , Tobias and Sextro, Walter}}, booktitle = {{Proceedings of the Second European Conference of the Prognostics and Health Management Society 2014}}, keywords = {{self-optimization reliability adaptive}}, title = {{{Closed-loop Control System for the Reliability of Intelligent Mechatronic Systems}}}, volume = {{5}}, year = {{2014}}, } @article{9885, abstract = {{Intelligent mechatronic systems, such as self-optimizing systems, allow an adaptation of the system behavior at runtime based on the current situation. To do so, they generally select among several pre-defined working points. A common method to determine working points for a mechatronic system is to use model-based multiobjective optimization. It allows finding compromises among conflicting objectives, called objective functions, by adapting parameters. To evaluate the system behavior for different parameter sets, a model of the system behavior is included in the objective functions and is evaluated during each function call. Intelligent mechatronic systems also have the ability to adapt their behavior based on their current reliability, thus increasing their availability, or on changed safety requirements; all of which are summed up by the common term dependability. To allow this adaptation, dependability can be considered in multiobjective optimization by including dependability-related objective functions. However, whereas performance-related objective functions are easily found, formulation of dependability-related objective functions is highly system-specific and not intuitive, making it complex and error-prone. Since each mechatronic system is different, individual failure modes have to be taken into account, which need to be found using common methods such as Failure-Modes and Effects Analysis or Fault Tree Analysis. Using component degradation models, which again are specific to the system at hand, the main loading factors can be determined. By including these in the model of the system behavior, the relation between working point and dependability can be formulated as an objective function. In our work, this approach is presented in more detail. It is exemplified using an actively actuated single plate dry clutch system. Results show that this approach is suitable for formulating dependability-related objective functions and that these can be used to extend system lifetime by adapting system behavior.}}, author = {{Meyer , Tobias and Sondermann-Wölke, Christoph and Sextro, Walter}}, journal = {{Conference Proceedings of the 2nd International Conference on System-Integrated Intelligence}}, keywords = {{Self-optimization, multiobjective optimization, objective function, dependability, intelligent system, behavior adaptation}}, pages = {{46--53}}, title = {{{Method to Identify Dependability Objectives in Multiobjective Optimization Problem}}}, doi = {{10.1016/j.protcy.2014.09.033}}, volume = {{15}}, year = {{2014}}, } @inproceedings{9887, abstract = {{A model to calculate the locally resolved tangential contact forces of the wheel rail contact with respect to contact kinematics, material and surface properties as well as temperature is introduced. The elasticity of wheel and rail is modeled as an elastic layer consisting of point contact elements connected by springs to each other and to the wheel. Each element has two degrees of freedom in tangential directions. The resulting total stiffness matrix is reduced to calculate only the position of the elements in contact. Friction forces as well as contact stiffnesses are incorporated by a nonlinear force-displacement characteristic, which originates from a detailed contact model. The contact elements are transported through the contact zone in discrete time steps. After each time step an equilibrium is calculated. For all elements, their temperature and its influence on local friction are regarded by calculating friction power and temperature each time step.}}, author = {{Neuhaus, Jan and Sextro, Walter}}, booktitle = {{Proceedings of the 5th International Conference on Computational Methods}}, editor = {{Liu, G.R. and Guan, Z.W.}}, keywords = {{Rolling Contact, Discrete Elements, Contact Stiffness, Temperature}}, publisher = {{ScienTech Publisher}}, title = {{{Thermo-Mechanical Model for Wheel Rail Contact using Coupled Point Contact Elements}}}, year = {{2014}}, } @article{9888, abstract = {{This paper discusses the refinement of multibody models by integration of flexible bodies and by considering nonlinearities from contacts. It presents common approaches for contact modeling in multibody simulations and strategies to include flexible bodies. A contact model is implemented in the elastic multibody model. Experimental results show that significant effects of system dynamics can be modeled by use of a multibody model including elastic bodies and contacts.}}, author = {{Schulze, Sebastian and Sextro, Walter and Grüter, Frank}}, issn = {{1617-7061}}, journal = {{PAMM}}, number = {{1}}, pages = {{39--40}}, publisher = {{WILEY-VCH Verlag}}, title = {{{Contact Modeling in Multibody Systems with Elastic Bodies in High-Frequency Applications}}}, doi = {{10.1002/pamm.201410012}}, volume = {{14}}, year = {{2014}}, } @inproceedings{9889, abstract = {{A measurement method is presented that combines the advantages of the multisine measurement technique with a prediction method for peak bending behavior. This combination allows the analysis of the dynamic behavior of mechanical structures at distinctly reduced measurement durations and has the advantage of reducing high excitation impacts on the structure under test.}}, author = {{Sprock, Christian and Sextro, Walter}}, booktitle = {{Instrumentation and Measurement Technology Conference (I2MTC) Proceedings, 2014 IEEE International}}, keywords = {{bending, dynamic testing, measurement, structural engineering, vibrations, measurement durations, mechanical structures, multisine measurement technique, nonlinear peak bending behavior, prediction method, time-efficient dynamic analysis, Heuristic algorithms, Nonlinear systems, Oscillators, Time measurement, Time-frequency analysis, Vibrations}}, pages = {{320--324}}, title = {{{Time-efficient dynamic analysis of structures exhibiting nonlinear peak bending}}}, doi = {{10.1109/I2MTC.2014.6860760}}, year = {{2014}}, }