The full model of a double-wishbone suspension has more than 30 differential-algebraic equations which takes a remarkably long time to simulate. By contrast, the look-up table for the same suspension is simulated much faster, but may not be very accurate. Therefore, developing reduced models that approximate complex systems is necessary because model reduction decreases the simulation time in comparison with the original model, enables real time applications, and produces acceptable accuracy. In this research, we focus on model reduction techniques for vehicle systems such as suspensions and how they are approximated by models having lower degrees of freedom. First, some existing model reduction techniques, such as irreducible realization procedures, balanced truncation, and activity-based reduction, are implemented to some vehicle suspensions. Based on the application of these techniques, their disadvantages are revealed. Then, two methods of model reduction for multi-body systems are proposed. The first proposed method is 2-norm power-based model reduction (2NPR) that combines 2-norm of power and genetic algorithms to derive reduced models having lower degrees of freedom and fewer number of components. In the 2NPR, some components such as mass, damper, and spring are removed from the original system. Afterward, the values of the remaining components are adjusted by the genetic algorithms. The most important advantage of the 2NPR is keeping the topology of multi-body systems which is useful for design purposes. The second method uses proper orthogonal decomposition. First, the equations of motion for a multi-body system are converted to explicit second-order differential equations. Second, the projection matrix is obtained from simulation or experimental data by proper orthogonal decomposition. Finally, the equations of motion are transferred to a lower-dimensional state coordinate system. The implementation of the 2NPR to two double-wishbone suspensions and the comparison with other techniques such as balanced truncation and activity-based model reduction also demonstrate the efficiency of the new reduction technique.

Orientador: Tamotsu Hirata / Banca: José Elias Tomazini / Banca: Luiz Fernando Costa Nascimento / Resumo: Um modelo fundamentado nos sistemas multicorpos, com sete corpos rígidos e oito corpos flexíveis, com três graus de liberdade para cada um dos corpos rígidos está sendo proposto. Os corpos rígidos são providos de inércia e os corpos flexíveis trabalham como juntas e não são providos de inércia. A solução numérica do modelo foi obtida com o método Runge-Kutta. Os parâmetros de influência, curvatura inicial da espinha lombar, posições dos centros geométricos das vértebras, tórax e da sacrum-pélvis, e o ponto de aplicação da força póstero-anterior (PA), foram obtidos de radiografia digital de cada paciente. O modelo foi simulado com dados de literaturas (obtidos de experimentos in vivo e em peças anatômicas). Os resultados foram satisfatórios do ponto de vista dos terapeutas e apresentam-se em conformidade com outros modelos propostos. O modelo oferece vantagem na aplicação individualizada a cada paciente pelos terapeutas, e foi construído com a metodologia de análise das forças aplicadas e suas reações diferentemente de outros modelos que apoiam-se nos métodos de análise das energias. O objetivo principal deste trabalho será o de avaliar o comportamento dinâmico do segmento lombar da coluna vertebral humana incluindo as massas do tórax e da pelve, por um modelo não-linear da rigidez viscoelástica estabelecido a partir da relação força-deslocamento obtida por experimentação in vivo. / Abstract: Evaluate a dynamic behavior of the human lumbar spine, with non-linear viscoelastic stiffness model followed by experimental data. Many of the techniques for the clinical treatment of dysfunction acting on lumber segments of the human spine have been based in the application of a postero anterior forces. Existing models to predict the state of lumber segments are restricted to evaluate general characteristic, furthermore, they use unrealistic boundary condition for its analysis. Periodic oscillatory posteroanterior forces were applied on each vertebra with initial lordotic curvature of the lumbar spine. A model is based on the multibody system of seven rigid bodies and eight deformable bodies representing human spine composed of thoratic, lumber and sacrum-pelvis segments. On each lumber were considered three degree of freedom(posterior - anterior, axial and flexion - extension). The rigid bodies are provided with inerti and the deformable bodies, wich would as joints with no inertia provided. Numerical solution of proposed model was solved with Ringe-Kutta methods. Parameter of influence, initial lordotic curvature, positions of the geometric centers of the vertebras, thorax and of the sacrum-pelvis, and point of application of the posteroanterior force (PA) were evaluated from x-ray image of patients. Nonlinear stiffness character introducedin the model affects the motion stability when periodic posteroanterior forces are applied to one vertebra. / Doutor

In computer simulation the term \"multibody system\" is usually employed to describe a system of interconnected bodies. Several examples of multibody systems can be found in railway engineering. A wheelset interacting with a track through a contact interface is just one example of practical interest. Modelling mechanical systems in a virtual environment contributes to the understanding of subjects such as dynamic behaviour, stability, durability, wear, fatigue, etc. In the context of a rigid-flexible multibody system mathematically described by a weak-form, the purpose of the present work is to evaluate the contributions due to rigid bodies considering their contact interactions. Inertial contributions due to distribution of mass of a rigid body are fully developed, considering a general pole position associated with a single node, representing a rigid body element. Rodrigues rotation parameters are used to describe finite rotations, by an updated Lagrangian description. Then, the so-called master-surface to master-surface contact formulation is adapted to be used in conjunction with the rigid body element and flexible bodies, aiming to consider their interaction in a rigid-flexible multibody environment. New surface parameterizations are proposed to establish contact pairs, permitting pointwise interaction in a frictional scenario. The proposed formulation is used to represent mechanical systems from different contexts, including a numerical example of the wheel-rail contact interface. The obtained results show the robustness and applicability of the methods. / Em simulação computacional o termo \"sistema multicorpos\" é usualmente empregado para descrever um sistema de corpos interconectados. Diversos exemplos de sistemas multicorpos podem ser encontrados no campo da engenharia ferroviária. Um rodeiro interagindo com a via através de uma interface de contato é apenas um dos exemplos de interesse prático. A modelagem de sistemas mecânicos em um ambiente virtual contribui para o entendimento de assuntos como comportamento dinâmico, estabilidade, durabilidade, desgaste, fadiga, etc. No contexto de um sistema multicorpos rígido-flexível descrito matematicamente por uma forma fraca, o propósito do presente trabalho é avaliar as contribuições devido à presença de corpos rígidos considerando interações de contato. Contribuições inerciais devido à distribuição de massa do corpo rígido são desenvolvidas e apresentadas em totalidade, considerando um polo genérico associado a um único nó, representando o corpo rígido. Parâmetros de rotação de Rodrigues são usados para descrever rotações finitas em uma descrição Lagrangiana atualizada. A formulação de contato master-surface to master-surface é adaptada para ser usada em conjunto com o elemento de corpo rígido e corpos flexíveis, estabelecendo a interação entre esses corpos em um ambiente de simulação multicorpos. Novas parametrizações de superfícies de contato são desenvolvidas para estabelecer os pares de contato, assumindo-se interações pontuais, em um cenário de contato com atrito. A formulação proposta é usada para representar sistemas mecânicos em diferentes contextos, incluindo um exemplo numérico do caso de contato roda-trilho. Os resultados obtidos mostram a robustez e a aplicabilidade dos métodos.

Entre as etapas do desenvolvimento de automóveis pode-se apontar a definição das características de suas suspensões. A fase de definição da suspensão pode ser dividida dentro do seguinte cenário: a escolha de um determinado tipo de suspensão, os pontos (geometria) e quais os valores de rigidez/amortecimento para todo o sistema irá resultar em um comportamento dinâmico desejado para o veículo, bem como a viabilidade de produção. Além disso, o entendimento da interação entre os parâmetros de suspensão, é crucial para a otimização do desempenho. Este trabalho pretende propor um método para aperfeiçoar a fase de \"tuning\" da suspensão, com foco principal no conforto. O veículo considerado é um caminhão comercial, e entre os seus parâmetros considerados estão rigidezes de molas da cabine e suspensão, amortecimento da suspensão de cabine e curvas do amortecedor da suspensão primária. O modelo virtual do veículo foi desenvolvido em ambiente ADAMS, o qual, previamente à otimização, foi validado contra dados experimentais. Métricas foram especialmente desenvolvidas levando em consideração aspectos subjetivos de conforto veicular, para dessa forma eliminar a variabilidade entre as avaliações subjetivas e análises das simulações. Os resultados mostraram expressivas melhorias no conforto e através de dados experimentais essas melhorias foram confirmadas. / Among the development phases of an automotive vehicle one can point out the definition of the characteristics of its suspensions. Suspension definition phase can be understood as the following scenario: given a suspension type, which hard points (geometric) and what values of stiffness/damping for the whole system will result in a desired dynamic behavior for the vehicle as well as production feasibility. Moreover, understanding the iteration among the suspension parameters, even considering just the tuning ones, is crucial for performance optimization. This work intends to propose a method for vehicle tuning characteristics optimization, having as a target the ride comfort. The vehicle considered here is a commercial truck, and among its parameters one considers cabin and suspension springs, cabin dampers and suspension damper curves. A vehicle model was developed in ADAMS environment and prior to the optimization the vehicle was validated against experimental data. Metrics were specially developed to take into account subjective aspects of ride, and, in this way, eliminating the gap between subjective evaluations and simulations analysis. Results showed improvements in ride comfort. The resulting setup was measured and the improvements were confirmed with experimental data.

Nos dias de hoje, a simulação dinâmica de veículos metroviários tem sido um importante método de análise e verificação, tanto no âmbito de projeto, como na engenharia de manutenção. Os pacotes de simulação disponíveis no mercado são altamente desenvolvidos e podem ser adaptados para os mais diversos cenários. O presente trabalho tem por objetivo demonstrar a funcionalidade destes programas, fundamentando a teoria por trás de seu algoritmo computacional, de maneira a expandir a fronteira de conhecimento nas engenharias de projeto e de manutenção. Para isso, são efetuados dois estudos de caso: passagem de veículo em região de abertura de bitola em curva de raio constante; passagem de veículo em sequencia de curvas reversas. Sendo assim, esta dissertação apresenta uma visão geral sobre o estado da arte na simulação da interação veículo e via permanente. / Nowadays, the dynamic simulation of metro vehicles have been an important method of analysis and verification in design engineering as in maintenance engineering. The simulation packages available are highly developed and can be adapted for different scenarios. This paper aims to demonstrate the functionality of these programs, supporting the theory behind its computational algorithm, in order to expand the frontier of knowledge in the national design and maintenance engineerings. For this, two case studies are made of: modelling flexible permanent way; modelling AMVs and crossings; passing vehicle in a region with gauge opening on a constant radius curve; passing a vehicle sequence of reverse curves. Thus, this dissertation presents an overview of the state of the art in the simulation of the interaction vehicle and permanent way of metro.

The motivation for this thesis was the need for further development of multibody dynamics simulation packages focused on detailed contact analysis. The thesis makes contributions in three different areas: Part I summarizes the equations, algorithms and design decisions necessary for dynamics simulation of flexible bodies with moving contacts. The assumed general shape function approach is presented. Additionally, the described technique enables studies of the residual stress release during grinding of flexible bodies. The proposed set of mode shapes was also successfully applied for modeling of heat flow. Part II is motivated by the need to reduce the computation time. The availability of the new cost-efficient multiprocessor computers triggered the development of the presented hybrid parallelization framework. The framework is designed to be easily portable and can be implemented without any system level coding or compiler modifications. Part III is motivated by the need for inter-operation with other simulation tools. A co-simulation framework based on the Transmission Line Modeling (TLM) technology was developed. The framework enables integration of several different simulation components into a single time-domain simulation. The framework has been used for connecting MSC.ADAMS and SKF BEAST simulation models. Throughout the thesis the approach was to present a practitioner roadmap. The detailed description of the theoretical results relevant for a real software implementation is put in focus. The software design decisions are discussed and the results of real industrial simulations are presented. This work has been supported by SKF, SSF/ProViking, ECSEL, KK-stiftelsen.

Les Artefacts de Tissus Mous (ATM) sont actuellement une des limitations principales pour la mesure du mouvement du membre supérieur avec les techniques actuelles d'analyse du mouvement. L'optimisation multi-segmentaire (OMS) a déjà prouvé son efficacité pour la mesure du mouvement du membre inférieur. Afin d'avoir la meilleure correction possible, il est nécessaire d'utiliser des modèles d'articulation proches de l'anatomie. L'objectif de cette thèse a donc été de développer et de valider un modèle du membre supérieur qui pourrait être utilisé pour la correction des ATM par OMS. De nouveaux modèles en boucle fermée de l'avant-bras et de la ceinture scapulaire ont ainsi été développés accompagnés d'un nouveau modèle de l'articulation scapulo-thoracique imposant à la scapula d'être tangente à un ellipsoïde modélisant le thorax. Ces nouveaux modèles ont été confrontés aux modèles courants de la littérature à travers une étude avec vis intra-corticales sur cadavre et in vivo sur sujets asymptomatiques. Des niveaux d'erreur similaires ont été observés pour tous les modèles quant à leur capacité de corriger les ATM et d'imiter la cinématique osseuse. Les nouveaux modèles semblent cependant beaucoup plus intéressants dans une perspective de développement d'un modèle musculo- squelettique. En effet, le modèle d'avant-bras autorise à la fois d'avoir le mouvement du radius et de l'ulna tandis que le modèle scapulo-thoracique représente mieux la contrainte existant entre le thorax et la scapula. En résumé, cette thèse a permis de développer un modèle complet proche de l'anatomie du membre supérieur permettant de corriger les ATM en utilisant une OMS. Bien que la correction des ATM obtenue n'est pas aussi satisfaisante qu'espérée, l'utilisation de cette approche pour le développement de futurs modèles musculo-squelettique a été validée / Soft Tissue Artefact (STA) is one of the most important limitations when measuring upper limb kinematics through marker-based motion capture techniques, especially for the scapula. Multi Body Optimisation (MBO) has already been proposed to correct STA when measuring lower limb kinematics and can be easily adapted for upper limb. For this purpose, the joint kinematic constraints should be as anatomical as possible. The aim of this thesis was thus to define and validate an anatomical upper limb kinematic model that could be used both to correct STA through the use of MBO and for future musculoskeletal models developments. For this purpose, a model integrating closed loop models of the forearm and of the scapula belt have been developed, including a new anatomical-based model of the scapulothoracic joint. This model constrained the scapula plane to be tangent to an ellipsoid modelling the thorax. All these models were confronted to typical models extracted from the literature through cadaveric and in vivo intracortical pins studies. All models generated similar error when evaluating their ability to mimic the bones kinematics and to correct STA. However, the new forearm and scapulothoracic models were more interesting when considering further musculoskeletal developments: The forearm model allows considering both the ulna and the radius and the scapulothoracic model better represents the constraint existing between the thorax and the scapula. This thesis allowed developing a complete anatomical upper limb kinematic chain. Although the STA correction obtained was not as good as expected, the use of this approach for a future musculoskeletal models has been validated

Chez Renault, pour réaliser les études amont, les équipes en charge de la prestation du choc automobile disposent de modèles très simples leur permettant de pré-dimensionner le véhicule. Aujourd'hui, ils sont construits à partir du comportement d'un ou quelques véhicules de référence. Ils sont fonctionnels et permettent le dimensionnement. Mais à présent, l'entreprise souhaite construire ses modèles amont en s'appuyant sur l'ensemble de ses véhicules. En d'autres termes, elle souhaite disposer d'une méthode d'analyse automatique de simulations de crashtests afin de capitaliser leurs résultats dans une base de données de modèles simplifiés.Pour répondre à cet objectif, nous développons une méthode permettant d'extraire des simulations de crashtests les données nécessaires à la construction d'un modèle multi-corps de substitution : CrashScan. Le processus d'analyse implémenté dans CrashScan se résume en trois étapes majeures.La première consiste à identifier l'ensemble des zones peu déformées sur une simulation de crashtest. Cela nous permet de dresser le graphe topologique du futur modèle de substitution. La seconde étape est une analyse des cinématiques relatives entre les portions peu déformées : les directions principales et les modes de déformation (e.g. compression, flexion) sont identifiés en analysant le mouvement relatif. La dernière étape consiste à analyser les efforts et les moments situés entre les zones peu déformées dans les repères associés aux directions principales des déformations en fonction des déformations. Cela nous permet d'identifier des modèles hystérétiques de Bouc-Wen équivalents. Ces modèles disposent de trois paramètres utiles dans notre cas : une raideur, un effort seuil avant plastification et une pente d'écrouissage. Ces paramètres peuvent être utilisés directement par les experts des études amont.Enfin, nous construisons les modèles multi-corps de substitution pour trois cas d'étude différents. Nous les comparons alors à leur référence sur les résultats qu'ils fournissent pour les critères utilisés en amont : les modèles générés par CrashScan semblent apporter la précision et la fidélité nécessaires pour être utilisés en amont du développement automobile.Pour poursuivre ces travaux de recherche et aboutir à une solution industrielle, il reste néanmoins des verrous à lever dont les principaux sont la synthèse d'un mouvement quelconque en six mouvements élémentaires et la synthèse multi-corps sur des éléments autres que des poutres. / At Renault, to fulfill upstream studies, teams in charge of crashworthiness use very simple models to pre-size the vehicle. Today, these models are built from the physical behavior of only one or some reference vehicles. They work and allow to size the project. But today, the company wishes to build its upstream models using all its vehicles. In other words, it wishes to get an automatic method to analyze crashtests simulations to capitalize their results in a database of simplified models.To meet this goal, we decide to use the multi-body model theory. We develop a method to analyze crashtests simulations in order to extract the data required to build a surrogate multi-body model : CrashScan. The analysis process implemented in CrashScan can be split into three major steps.The first one allows to identify the low deformed zones on a crashtest simulation. Then, we can build the topological graph of the future surrogate model. The second step is to analyze the relative kinematics between the low deformed zones : major directions and deformation modes (e.g. crushing or bending) are identified analysing relative movements. The last step is to analyze strengths and moments located between the low deformed zones, viewed in the frames associated to the major directions of deformations in function of the deformations. This allows us to identify equivalent Bouc-Wen hysteretic models. These models have three parameters that we can use : a stiffness, a threshold strength before plastification and a strain of hardening. These parameters can directly be used by upstream studies experts.Finally, we build multi-body models for three different use case. We compare them to their reference over the results they produce for the upstream criteria : models generated with CrashScan seems to grant the precision and the fidelity required to be used during automotive development's upstream phases.To continue this research work and get an industrial solution, there are still some locks to lift, the main ones are : synthesis of any movement into six elementary ones and multi-body synthesis on elements other than beams.

Wheel loaders are heavy duty machines that are ubiquitous on construction sites and in mines all over the world. Fully autonomous wheel loaders remains an open problem but the industry is hoping that increasing their level of autonomy will help to reduce costs and energy consumption while also increasing workplace safety. Operating a wheel loader efficiently requires dig plans that extend over multiple dig cycles and not just one at a time. This calls for a model that can predict both the performance of a dig action and the resulting shape of the pile. In this thesis project, we use simulations to develop a data-driven artificial neural network model that can predict the outcome of a dig action. The model is able to predict the wheel loader’s productivity with an average error of 7.3% and the altered shape of the pile with an average relative error of 4.5%. We also show that automatic differentiation techniques can be used to accurately differentiate the model with respect to input. This makes it possible to use gradient-based optimization methods to find the dig action that maximises the performance of the wheel loader.

The thesis deals with building and utilization of mechatronic models which are based on modeling of system of rigid and flexible bodies. Such models are then used for analysis of behavior of complex systems, for instance machine tools. The work is concentrated on analysis of self-excitation of a machine tool. The appearance of the self-excitation during the machining may be influenced by several methods described in the work. The evaluation of the appearance of the self-excitation is analyzed via so called lobe diagram. It is necessary to know transfer function describing the impact of acting forces on the deformation of the system (machine tool in this case) for compilation of the lobe diagram. The whole structure of the model shows compliant behavior which dramatically influences the transfer function thus the approach to the modeling of mechanical parts as flexible bodies is proposed. There are created models of modally reduced flexible bodies based on modified CAD models which have same modal properties as non-reduced FEM models up to the maximal excitation frequency. The reduced models have significantly lower number of degrees of freedom and it is possible to work with them in multi-body simulation tools and at the same time they contain the information about the deformations. The work utilizes Graig-Bamton method which is implemented to the ANSYS. The whole model is consequently built and analyzed in ADAMS. It is possible to export the linearized model of the system in form of state matrices which are used for writing of the transfer function. The conditions of stability of the machining process are then evaluated via the lobe diagram. The proposed thesis presents the modeling of mechatronic systems with stiff and rigid bodies. The approach may be used for analysis of machining tools as well as for development of advanced mechatronic systems with active damping, etc.