Encontrados 18 documentos, a visualizar página 1 de 2
On dynamic analysis of contact problems with freeform surfaces : a knee joint 3...
Machado, Margarida F.; Flores, Paulo; Lopes, Daniel S.; Ambrósio, JorgeOne of the biomechanical roles of the knee joint is to withstand high loading forces. Thus, this articulation is quite susceptible to injuries and diseases, which may cause anomalous contact loads, asymmetrical gait patterns and local pain that, ultimately, leads to a knee replacement. In view of that, identifying and quantifying the loads placed on the human knee is critical for understanding realistic joint m...
On the contact detection for contact-impact analysis in multibody systems
Flores, Paulo; Ambrósio, JorgeOne of the most important and complex parts of the simulation of multibody systems with contact-impact involves the detection of the precise instant of impact. In general, the periods of contact are very small and, therefore, the selection of the time step for the integration of the time derivatives of the state variables plays a crucial role in the dynamics of multibody systems. The conservative approach is to...
A mathematical framework for contact detection between quadric and superquadric...
Lopes, Daniel S.; Silva, Miguel T.; Ambrósio, Jorge A.; Flores, PauloThe calculation of the minimum distance between surfaces plays an important role in computational mechanics, namely, in the study of constrained multibody systems where contact forces take part. In this paper, a general rigid contact detection methodology for non-conformal bodies, described by ellipsoidal and superellipsoidal surfaces, is presented. The mathematical framework relies on simple algebraic and diff...
Development of a planar multi-body model of the human knee joint
Machado, Margarida F.; Flores, Paulo; Claro, José Carlos Pimenta; Ambrósio, Jorge; Silva, Miguel; Completo, António; Lankarani, Hamid M.The aim of this work is to develop a dynamic model for the biological human knee joint. The model is formulated in the framework of multibody systems methodologies, as a system of two bodies, the femur and the tibia. For the purpose of describing the formulation, the relative motion of the tibia with respect to the femur is considered. Due to their higher stiffness compared to that of the articular cartilages, ...
Lubricated revolute joints in rigid multibody systems
Flores, Paulo; Ambrósio, Jorge; Claro, José Carlos Pimenta; Lankarani, H. M.; Koshy, C. S.The main purpose of this work is to present a general methodology for modeling lubricated revolute joints in constrained rigid multibody systems. In the dynamic analysis of journal-bearings, the hydrodynamic forces, which include both squeeze and wedge effects, generated by the lubricant fluid, oppose the journal motion. The hydrodynamic forces are obtained by integrating the pressure distribution evaluated wit...
Sensitivity analysis of flexible multibody systems using composite materials co...
Neto, Maria Augusta; Ambrósio, Jorge A. C.; Leal, Rogério PereiraIn this paper, a general formulation for the computation of the first-order analytical sensitivities based on the direct method using automatic differentiation of flexible multibody systems is presented. The direct method for sensitivity calculation is obtained by differentiating the equations that define the response of the flexible multibody systems of composite materials with respect to the design variables,...
Translational joints with clearance in rigid multibody systems
Flores, Paulo; Ambrósio, Jorge; Claro, José Carlos Pimenta; Lankarani, H. M.A computational methodology for dynamic description of rigid multibody systems with translational clearance joints is presented and discussed in this work. Over the last years, extensive work has been done to study the dynamic effect of the revolute joints with clearance in multibody systems, in contrast with the little work devoted to model translational joints with clearance. In a joint with translation clear...
Optimization of a complex flexible multibody systems with composite materials
Ambrósio, Jorge; Neto, Maria; Leal, RogérioAbstract The paper presents a general optimization methodology for flexible multibody systems which is demonstrated to find optimal layouts of fiber composite structures components. The goal of the optimization process is to minimize the structural deformation and, simultaneously, to fulfill a set of multidisciplinary constraints, by finding the optimal values for the fiber orientation of composite structures...
Dynamic behaviour of planar rigid multi-body systems including revolute joints ...
Flores, Paulo; Ambrósio, Jorge; Claro, José Carlos Pimenta; Lankarani, H. M.This paper deals with a general methodology to assess the influence of the clearance size and the friction coefficient on the dynamic response of planar rigid multi-body systems including revolute joints with clearance. When there is a clearance in a revolute joint, impacts between the journal and the bearing can occur, and consequently, local deformations take place. The impact is internal and the response of ...
Composite materials in flexible multibody systems
Neto, Maria Augusta; Ambrósio, Jorge A. C.; Leal, Rogério P.In this work the flexible multibody dynamics formulations of complex models are extended to include elastic components made of laminated composite materials. The only limitation for the deformation of a structural member is that it must be elastic and linear when described in a body fixed frame. A finite element model for each flexible body is obtained such that the nodal coordinates are described with respect ...
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