Getriebeheulphänomenen wird in der industriellen Praxis zum Teil noch immer ausschließlich mit Hilfe einer optimierten Verzahnungsauslegung zur Minimierung des Drehfehlers begegnet. Bei auffälligen Resonanzerscheinungen werden zudem Strukturoptimierungen am Getriebegehäuse und den Karosserieanbindungspunkten des Antriebsstrangs vorgenommen, ohne auf die internen Systemkomponenten verstärkt einzugehen. Zudem kann bisher die verlässliche Erkenntnis, dass zur Einhaltung akustischer Grenzwerte die Konstruktion nochmals überarbeitet werden muss, erst spät im Entwicklungsprozess während der akustischen Versuchsdurchführung an Prüfständen oder im Fahrzeug getroffen werden. Durch sogenannte Sekundärmaßnahmen, die typischerweise nicht unmittelbar das Anregungsverhalten oder die Dynamik des Antriebsstrangs, sondern den karosserieseitigen Transferpfad betreffen, kann eine Reduktion des Schalldruckpegels im Fahrzeuginnenraum in gewissen Grenzen erzielt werden. Dies ist zumeist weder aus ingenieurstechnischer Sicht noch aus Sicht steigender Entwicklungskosten als optimal zu bezeichnen. Basierend auf einem detaillierten Abgleich zwischen Experiment und Simulation, angefangen auf Einzelteilebene über die Baugruppenebene bis hin zur Methodenentwicklung der Validierung von nichtrotierenden Gesamtsystemen mittels künstlicher Anregung, werden in dieser Arbeit möglichst akkurate Simulationsergebnisse angestrebt, um die Auswirkung von akustischen Optimierungen innerhalb der Simulationsumgebung realitätsnah vorherzusagen. Schließlich wird ein Prozess vorgeschlagen, der eine getriebeinterne Transferpfadanalyse zur Identifikation sensitiver Körperschallpfade vorstellt. Mit dieser Methode wird aufgezeigt, dass es möglich ist, akustische Schwachstellen auf der Antriebsstrangseite vorherzusagen. Dabei kann zum einen akustisches Optimierungspotenzial des Welle-Lager-Systems abgeleitet werden, zum anderen werden auch die aktuellen Möglichkeiten und Grenzen der Verfahren beleuchtet.:Inhaltsverzeichnis Abbildungsverzeichnis Formelzeichen und Abkürzungen 1 Einleitung 2 Stand der Technik 2.1 Getriebeakustik – Einflussgrößen und Begrifflichkeiten 2.1.1 Verzahnungsanregung von unter Last stehenden Zahnrädern 2.1.2 Verzahnungsinduzierte Körper- und Luftschallweiterleitung in Fahrzeugen 2.1.3 Maßnahmen zur Reduktion von Körperschallpfaden 2.2 Strukturdynamische Analysemethoden in der Getriebeakustik 2.2.1 Numerische Modalanalyse 2.2.2 Experimentelle Modalanalyse und Betriebsschwingformanalyse 2.2.3 Unkonventionelle Methoden zur Erregung von Bauteilstrukturen 2.2.4 Computerunterstützte Modellanpassung 2.2.5 Transferpfadanalyse 2.3 Getriebesimulation 2.3.1 Getriebetypische Kontaktmodellierung 2.3.2 Finite-Element-Modellierung und Reduktionsverfahren 2.4 Fazit 3 Zielsetzung und Vorgehensweise 4 Methoden zur Analyse von Getriebekomponenten 4.1 Verzahnungsanalyse 4.2 Strukturdynamische Untersuchungen an Einzelteilen 4.3 Strukturdynamische Untersuchungen an Baugruppen 4.4 Verhalten von Wälzlagern 4.5 Fazit 5 Methode zur Gesamtsystemvalidierung 5.1 Modellierung des Getriebesystems mit Prüfstandsanbindung 5.2 Getriebeinterne Anregung mittels Zahnaktor 5.2.1 Voruntersuchungen 5.2.2 Implementierung einer torsionalen Anregung in Frontgetrieben 5.2.3 Simulative und experimentelle Untersuchungen 5.3 Fazit 6 Getriebeinterne Transferpfadanalyse 6.1 Identifikation sensibler Körperschalltransferpfade 6.2 Optimierungsansätze 6.3 Fazit 7 Zusammenfassung und Ausblick 8 Literaturverzeichnis / Gear whine phenomena are typically mitigated by optimising gear design to minimise Transmission Error. Additionally, structural optimisations on the gearbox housing and on the gearbox-to-chassis mounts may be conducted most likely without a detailed consideration of internal components‘ dynamics. Moreover, it is not unusual that in the final stages of drivetrain developments when the gearbox is tested on test benches or in vehicles NVH targets are not met. The countermeasures applied often do not alter the source of excitation nor the dynamics of the drivetrain at this stage, but the vehicle transfer paths through the chassis. Thus, sound power level reduction may be exclusively limited to vehicle transfer path improvements. In most cases this is not regarded as an optimal solution neither from an engineering perspective nor from the commercial point of view due to increased development costs. Based on detailed correlation activities where simulation has been run against measurement the work strives to achieve accurate gearbox NVH predictions to forecast more realistically the effect of design optimisations. The correlation approach starts on single component level moving on to sub-assembly level and finally up to the development of a method which is able to artificially excite the entire but non-rotating drivetrain. After various successful correlation studies, a process has been elaborated which proposes a gearbox internal transfer path analysis to identify potentially critical structure-borne noise paths. The method illustrates the capability of successfully predicting weak spots at the active side of a drivetrain early in the development process. Additional room for improvement can be derived when implementing this method by considering the rotating components of a drivetrain such as gear blanks, shafts and bearings.:Inhaltsverzeichnis Abbildungsverzeichnis Formelzeichen und Abkürzungen 1 Einleitung 2 Stand der Technik 2.1 Getriebeakustik – Einflussgrößen und Begrifflichkeiten 2.1.1 Verzahnungsanregung von unter Last stehenden Zahnrädern 2.1.2 Verzahnungsinduzierte Körper- und Luftschallweiterleitung in Fahrzeugen 2.1.3 Maßnahmen zur Reduktion von Körperschallpfaden 2.2 Strukturdynamische Analysemethoden in der Getriebeakustik 2.2.1 Numerische Modalanalyse 2.2.2 Experimentelle Modalanalyse und Betriebsschwingformanalyse 2.2.3 Unkonventionelle Methoden zur Erregung von Bauteilstrukturen 2.2.4 Computerunterstützte Modellanpassung 2.2.5 Transferpfadanalyse 2.3 Getriebesimulation 2.3.1 Getriebetypische Kontaktmodellierung 2.3.2 Finite-Element-Modellierung und Reduktionsverfahren 2.4 Fazit 3 Zielsetzung und Vorgehensweise 4 Methoden zur Analyse von Getriebekomponenten 4.1 Verzahnungsanalyse 4.2 Strukturdynamische Untersuchungen an Einzelteilen 4.3 Strukturdynamische Untersuchungen an Baugruppen 4.4 Verhalten von Wälzlagern 4.5 Fazit 5 Methode zur Gesamtsystemvalidierung 5.1 Modellierung des Getriebesystems mit Prüfstandsanbindung 5.2 Getriebeinterne Anregung mittels Zahnaktor 5.2.1 Voruntersuchungen 5.2.2 Implementierung einer torsionalen Anregung in Frontgetrieben 5.2.3 Simulative und experimentelle Untersuchungen 5.3 Fazit 6 Getriebeinterne Transferpfadanalyse 6.1 Identifikation sensibler Körperschalltransferpfade 6.2 Optimierungsansätze 6.3 Fazit 7 Zusammenfassung und Ausblick 8 Literaturverzeichnis

Recent years have seen increasing research interest in structural health monitoring (SHM). Among the many advances in SHM research, “smart” wireless sensors capable of embedded computing and wireless communication have been highly attractive. Wireless communication in SHM systems was originally proposed to significantly reduce the monetary and time cost for installing lengthy cables in an SHM system. Besides wireless sensing, the next revolution in sensor networks has been predicted to be mobile sensor networks that implant mobility into traditional wireless sensor networks. This research explores decentralized structural model updating and damage detection using mobile and wireless sensors. In the first stage of this research, mobile sensing nodes (MSNs) are developed for SHM purposes. The MSNs can maneuver upon structures built with ferromagnetic/steel materials, conduct measurement, and communicate with pears or remote servers wirelessly. The performance of the MSNs is validated through laboratory and field experiments. To further investigate the mobile sensing strategy, a decentralized structural damage detection procedure is proposed herein for the MSNs using transmissibility functions. Laboratory experiments are conducted on a steel portal frame where various structure damage scenarios are emulated. Besides experiments with MSNs, this study also investigates the nature of transmissibility functions for damage detection in an analytical manner based on a general multi-DOF spring-mass-damper system. Finally, this research also explores substructure model updating through minimization of modal dynamic residuals, which can best benefit from dense mobile or wireless sensor data concentrated in one area. Craig-Bampton transform is adopted to condense the structural model, and minimization of the modal dynamic residuals is determined as the optimization objective. An iterative linearization procedure is adopted for efficiently solving the optimization problem. The presented substructure updating method is validated through a few numerical examples. For comparison, a conventional approach minimizing modal property differences is also applied, and shows worse updating accuracy than the proposed approach. The performance of the proposed substructure model updating approach is further investigated on the effects of substructure location and size.

Orientador: João Antônio Pereira / Banca: Amarildo Tabone Paschoalini / Banca: Heraldo Nélio Cambraia / Resumo: O presente trabalho propõe uma metodologia de ajuste de modelos de elementos finitos aplicado a problemas de contato. O ajuste do modelo é realizado através da atualização dos parâmetros físicos e/ou geométricos do modelo bem como dos parâmetros dos elementos de contato. O método utilizado é baseado nas FRF(s) e é formulado a partir de um resíduo de entrada, dado pelo balanço de força do sistema. Um software é implementado para fazer a comparação e correlação dos modelos analítico e experimental, e se necessário, ajustar os parâmetros do modelo analítico. O modelo analítico é gerado pelo software comercial ANSYSâ, e os dados experimentais são obtidos em testes experimentais de análise modal. A metodologia foi avaliada com exemplos numéricos e testes experimentais buscando identificar as potencialidades e limitações do método. Dois testes experimentais foram realizados. O primeiro teste consiste em obter os parâmetros modais de uma estrutura simples do tipo viga. No segundo teste, os parâmetros modais são obtidos de uma estrutura composta por duas peças em contato. O objetivo do primeiro teste é avaliar a potencialidade da metodologia proposta utilizando uma base de dados experimental confiável, já que a estrutura é simples e suas propriedades são bem conhecidas. O segundo teste tem por objetivo avaliar a metodologia para o problema de contato. Os resultados apresentados mostram a funcionalidade da metodologia. O ajuste foi realizado com êxito tanto para a estrutura simples como para a estrutura composta por duas peças em contato. / Abstract: The present work proposes a finite element model updating methodology applied to problems of contact. The updating of the models is accomplished through the updating of the physical and/or geometric parameters of the model as well as the parameters of the contact elements. The approach is a FRF-based method; it is formulated from input residue, given by the equilibrium force of the system. It is implemented a software to makes the comparison and correlation of the analytical and experimental models, and if necessary, to adjust the parameters of the analytic model based in the experimental data, in order to get a more reliable finite element model. The analytical model is created by the commercial software ANSYSâ, and the experimental data are obtained by experimental modal tests. The methodology was evaluated with numeric and experimental data aiming at identifying of the potentialities and limitations of the method. Two experimental tests were developed, the first test consists of the analyses of a beam like structure and the second one, the analysis of a structure composed by two pieces in contact. The aim of the first test is to evaluate the potentiality of the methodology using a reliable experimental base of data, since the structure is simple and its properties are very wellknown. The second test has for objective to evaluate the methodology for problems of contact. The presented results have shown the functionality of the methodology. The adjustment was accomplished with relative success for the simple structure as well as for the structure composed by two pieces in contact. / Mestre

Mathematical models that are built in order to simulate the behavior of structures, most often, tend to respond differently than the actual structures in their initial state. In order to use the mathematical models and their computational outputs instead of testing the real structure under every possible case, it is mandatory to have a mathematical model that reflects the characteristics of the actual structure in the best possible way. In this thesis, the so called model updating techniques used for updating the mathematical models in order to make them respond in the way the actual structures do are investigated. Case studies using computationally generated test data are performed using the direct and indirect modal updating techniques with the software developed for each method investigated. After investigating the direct and indirect modal updating techniques, two of them, one using frequency response functions and the other using modal sensitivities, are determined to be the most suitable ones for aircraft structures. A generic software is developed for the technique using modal sensitivities. A modal test is carried out on a scaled aircraft model. The test data is used for updating of the finite element model of the scaled aircraft using the modal sensitivities and the usability of the method is thus evaluated. The finite element model of a real aircraft using the modal test data is also updated using the modal sensitivities. A new error localization technique and a model updating routine are also proposed in this thesis. This modal updating routine is used with several case studies using computationally generated test data and it is concluded that it is capable of updating the mathematical models even with incomplete measured data.

Made available in DSpace on 2014-06-11T19:27:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-10-31Bitstream added on 2014-06-13T19:55:35Z : No. of bitstreams: 1 garcia_am_me_ilha.pdf: 659750 bytes, checksum: 7318de4cdef56cfcd2a84f0bc10c3fbb (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O presente trabalho propõe uma metodologia de ajuste de modelos de elementos finitos aplicado a problemas de contato. O ajuste do modelo é realizado através da atualização dos parâmetros físicos e/ou geométricos do modelo bem como dos parâmetros dos elementos de contato. O método utilizado é baseado nas FRF(s) e é formulado a partir de um resíduo de entrada, dado pelo balanço de força do sistema. Um software é implementado para fazer a comparação e correlação dos modelos analítico e experimental, e se necessário, ajustar os parâmetros do modelo analítico. O modelo analítico é gerado pelo software comercial ANSYSâ, e os dados experimentais são obtidos em testes experimentais de análise modal. A metodologia foi avaliada com exemplos numéricos e testes experimentais buscando identificar as potencialidades e limitações do método. Dois testes experimentais foram realizados. O primeiro teste consiste em obter os parâmetros modais de uma estrutura simples do tipo viga. No segundo teste, os parâmetros modais são obtidos de uma estrutura composta por duas peças em contato. O objetivo do primeiro teste é avaliar a potencialidade da metodologia proposta utilizando uma base de dados experimental confiável, já que a estrutura é simples e suas propriedades são bem conhecidas. O segundo teste tem por objetivo avaliar a metodologia para o problema de contato. Os resultados apresentados mostram a funcionalidade da metodologia. O ajuste foi realizado com êxito tanto para a estrutura simples como para a estrutura composta por duas peças em contato. / The present work proposes a finite element model updating methodology applied to problems of contact. The updating of the models is accomplished through the updating of the physical and/or geometric parameters of the model as well as the parameters of the contact elements. The approach is a FRF-based method; it is formulated from input residue, given by the equilibrium force of the system. It is implemented a software to makes the comparison and correlation of the analytical and experimental models, and if necessary, to adjust the parameters of the analytic model based in the experimental data, in order to get a more reliable finite element model. The analytical model is created by the commercial software ANSYSâ, and the experimental data are obtained by experimental modal tests. The methodology was evaluated with numeric and experimental data aiming at identifying of the potentialities and limitations of the method. Two experimental tests were developed, the first test consists of the analyses of a beam like structure and the second one, the analysis of a structure composed by two pieces in contact. The aim of the first test is to evaluate the potentiality of the methodology using a reliable experimental base of data, since the structure is simple and its properties are very wellknown. The second test has for objective to evaluate the methodology for problems of contact. The presented results have shown the functionality of the methodology. The adjustment was accomplished with relative success for the simple structure as well as for the structure composed by two pieces in contact.

Most tyre models developed to date require a fair amount of data before an accurate representation of the tyre can be obtained. This study entails the development of a simplified, yet accurate, non-linear Finite Element (FE) model of an “off-road” tyre to study the behaviour of the tyre due to radial loading conditions. The study aims to develop a FE tyre model that can solve fast and be accurate enough to be used in multibody dynamic vehicle simulations. A model that is less complex than conventional detailed FE models is developed. The work explores the use of superimposed finite elements to model the varying stiffness in the respective orthogonal directions of the sidewall and tread of the tyre. Non-linear elements defined by Neo-Hookean or Ogden models and elements with different linear orthogonal stiffnesses are superimposed onto each other to simulate the global material properties of the tread and the sidewall of the tyre investigated. The geometry of the tyre studied was measured experimentally using laser displacement transducers and digital image correlation techniques. Material properties of segments of the tyre were obtained by performing tensile tests on samples. Since the rubber slipped against the clamps during the experiment, deformation of the segments was also measured using digital image correlation. These geometrical and material properties were used as input to develop a finite element model of an “off-road” tyre. Measurements were conducted using laser displacement transducers, load cells mounted to actuators, etc. to obtain accurate sidewall deformation profiles and global radial load vs. displacement curves for different radial loading conditions. The data obtained from the results was used to validate the tyre model developed. Numerous analyses are performed with different combinations of moduli of elasticity in the respective orthogonal directions of the sidewall stiffness and the tread to investigate its influence on the global behaviour of the tyre model. The main focus of the project was to develop a tyre model from data obtained from laser and photogrammetry measurements in a laboratory that accurately represents tyre behaviour due to radial forces. A finite element model that can simulate the effect of radial forced and obstacles on a tyre was developed. The use of two subsets of elements, superimposed onto each other to simulate global material properties of the rubbers, steel wires, polyester and nylon threads, was investigated. The combination of material properties that gave the best fit for all the load cases investigated were determined. The finite element model correlated well with the load vs. displacement graphs and sidewall displacement profiles determined experimentally. The solving time is still fairly high and is still not quite suitable for real-time dynamic simulation. However, it solves faster than more complex tyre models where details of steel wires, etc. are included in the model. For future studies it is recommended that different element types be investigated in the tyre model. The study proves that equivalent material properties can be used to simulate the composite properties of the materials in tyres. Most tyres can be divided into a few regions that each has its own material structure right through the region. These regions can be characterized by simple tests and the input can be used as a first estimation of the tyre’s material properties for the model. Accurate validation criteria should be used to validate the tyre model if time does not allow for excessive testing of the material properties of all the rubber, steel wires, polyester threads, etc. Geometric displacement data at various loading conditions can be used for validation of the tyre model. The model developed can be used to investigate the effect of different stiffnesses and other material changes in the sidewall or tread of a tyre. Useful insight can be obtained from the finite element model developed for dynamic simulation where the force vs. global displacement data is important. / Dissertation (MEng)--University of Pretoria, 2014. / tm2015 / Mechanical and Aeronautical Engineering / MEng / Unrestricted

More and more pressure is exerted on railway infrastructure due to an increasing transportation demand and population density. Instead of expanding the net, a possible solution could lie in the enlargement of the capacity by operating longer trains rather than more short ones. However, close attention has to be paid to the behaviour and the lifetime of the infrastructure under these changed loads. In special bridges are delicate aspects in this matter. In the current thesis the simply supported Banafjäl bridge located on the Bothnia Line in the North of Sweden is studied more in detail with regards to this aspect. It is a high-speed composite railway bridge with a span of 42 m. A detailed 3D finite element (FE) model is made available. However in order to make reliable predictions about the behaviour under increasing train length loads, it had to be further improved. Different methods of calibrating measured response data to an existing FE model, finite element model updating (FEMU), are available and a detailed overview is given at the beginning of this thesis. Next a sensitivity analysis was performed to select the material parameters which are most influential for the result and will be updated. In the following, FEMU is carried out by means of two iterative updating methods, genetic and gradient-based optimization, after which also a combination of these two is implemented. Two objective functions are chosen and it is shown that all methods converge to a global optimal solution. After adjusting the initial model with the updated parameter values, a fatigue analysis on this updated model is carried out for high-speed trains of multiple lengthsby means of the Palmgren-Miner rule. The fatigue is found to increase with increasing train length and in particular when the speed approaches resonance speed. By extension an operating chart is created to indicate the maximum amount of train passages per day in function of speed and train length for a type 4 fatigue train. Furthermore, damping has been shown to have a positive effect on the fatigue, the larger this effect for shorter trains. The static behaviour has been proven not to be a problem and so will solely the weight of trains induce little to no fatigue problems in this particular bridge.

No description available.

Structural Health Monitoring (SHM) is a promising tool for condition assessment of bridge structures. SHM of bridges can be performed for different purposes in long or short-term. A few aspects of short- and long-term monitoring of highway bridges are addressed in this research. Without quantifying environmental effects, applying vibration-based damage detection techniques may result in false damage identification. As part of a long-term monitoring project, the effect of temperature on vibrational characteristics of two continuously monitored bridges are studied. Natural frequencies of the structures are identified from ambient vibration data using the Natural Excitation Technique (NExT) along with the Eigen System Realization (ERA) algorithm. Variability of identified natural frequencies is investigated based on statistical properties of identified frequencies. Different statistical models are tested and the most accurate model is selected to remove the effect of temperature from the identified frequencies. After removing temperature effects, different damage cases are simulated on calibrated finite-element models. Comparing the effect of simulated damages on natural frequencies showed what levels of damage could be detected with this method. Evaluating traffic loads can be helpful to different areas including bridge design and assessment, pavement design and maintenance, fatigue analysis, economic studies and enforcement of legal weight limits. In this study, feasibility of using a single-span bridge as a weigh-in-motion tool to quantify the gross vehicle weights (GVW) of trucks is studied. As part of a short-term monitoring project, this bridge was subjected to four sets of high speed, live-load tests. Measured strain data are used to implement bridge weigh-in-motion (B-WIM) algorithms and calculate the corresponding velocities and GVWs. A comparison is made between calculated and static weights, and furthermore, between supposed speeds and estimated speeds of the trucks. Vibration-based techniques that use finite-element (FE) model updating for SHM of bridges are common for infrastructure applications. This study presents the application of both static and dynamic-based FE model updating of a full scale bridge. Both dynamic and live-load testing were conducted on this bridge and vibration, strain, and deflections were measured at different locations. A FE model is calibrated using different error functions. This model could capture both global and local response of the structure and the performance of the updated model is validated with part of the collected measurements that were not included in the calibration process.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20760号 / 工博第4412号 / 新制||工||1686(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 杉浦 邦征, 教授 白土 博通, 教授 清野 純史 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM