/pdf/convex-analysisnoer-san-nojin-zhan-nituite-5dl2rbmoyr.pdf

Convex Analysisの二,三の進展について

Initial-value ordinary differential equation solution via variable order Adams method (SIVA/DIVA) package is collection of subroutines for solution of nonstiff ordinary differential equations. There are versions for single-precision and double-precision arithmetic. Requires fewer evaluations of derivatives than other variable-order Adams predictor/ corrector methods. Option for direct integration of second-order equations makes integration of trajectory problems significantly more efficient. Written in FORTRAN 77.

Solving Ordinary Differential Equations

This paper describes modern techniques used to solve contact problems within Computational Mechanics. On the basis of a continuum description of contact, the mathematical structure of the contact formulation for finite element methods is derived. Emphasis is also placed on the constitutive behavior at the contact interface for normal and tangential (frictional) contact. Furthermore, different discretization schemes currently applied to solve engineering problems are formulated for small and finite strain problems. These include isoparametric interpolations, node-to-segment discretizations and also mortar and Nitsche techniques. Furthermore, several algorithms related to spatial contact search and fulfillment of the inequality constraints at the contact interface are discussed. Here, especially the penalty and Lagrange multiplier schemes are considered and also SQP- and linear-programming methods are reviewed.


Keywords:

contact mechanics;
friction;
penalty method;
Lagrange multiplier method;
contact algorithms;
finite element method;
finite deformations;
discretization methods

Computational Contact Mechanics

Rigid Body Dynamics Algorithms presents the subject of computational rigid-body dynamics through the medium of spatial 6D vector notation. It explains how to model a rigid-body system and how to analyze it, and it presents the most comprehensive collection of the best rigid-bodydynamics algorithms to be found in a single source. The use of spatial vector notation greatly reduces the volume of algebra which allows systems to be described using fewer equations and fewer quantities. It also allows problems to be solved in fewer steps, and solutions to be expressed more succinctly. In addition algorithms are explained simply and clearly, and are expressed in a compact form. The use of spatial vector notation facilitates the implementation of dynamics algorithms on a computer: shorter, simpler code that is easier to write, understand and debug, with no loss of efficiency.

Rigid Body Dynamics Algorithms

This article has presented an introductory tutorial on discontinuous dynamical systems. Various examples illustrate the pertinence of the continuity and Lipschitzness properties that guarantee the existence and uniqueness of classical solutions to ordinary differential equations. The lack of these properties in examples drawn from various disciplines motivates the need for more general notions than the classical one. First, we introduced notions of solution for discontinuous systems. Second, we reviewed the available tools from non- smooth analysis to study the gradient information of candidate Lyapunov functions. And, third, we presented nonsmooth stability tools to characterize the asymptotic behavior of solutions.

Discontinuous dynamical systems

THEORY. Multibody Kinematics. Dynamics of Rigid Body Systems. Contact Kinematics. Multiple Contact Configurations. Detachment and Stick-Slip Transitions. Frictionless Impacts by Newton's Law. Impacts with Friction by Poisson's Law. The Corner Law of Contact Dynamics. APPLICATIONS. Applications with Discontinuous Force Laws. Applications with Classical Impact Theory. Applications with Coulomb's Friction Law. Applications with Impacts and Friction. References. Index.

Multibody dynamics with unilateral contacts

1. Introduction.- 1.1 Friction Laws.- 1.2 Literature Survey.- 1.3 Subjects and Contents.- 2. Fundamental Concepts.- 2.1 Internal and External Forces.- 2.2 The Law of Interaction.- 2.3 The Dynamic Equilibrium.- 2.4 The Virtual Work of a Dynamic System.- 2.5 Resultant Force and Inertia Terms.- 3. Rigid Body Systems.- 3.1 Preliminaries on the Vector Product.- 3.2 Rigid Body Kinematics.- 3.3 Rigid Body Kinetics.- 3.4 The Dynamic Equilibrium of a Rigid Body.- 3.5 The Virtual Work of a Rigid Body System.- 3.6 Classical Bilateral Constraints.- 3.7 Generalized Coordinates.- 4. Motion and Discontinuity Events.- 4.1 Preliminaries on Integration of Functions.- 4.2 Displacements, Velocities, and Accelerations.- 4.3 Restriction to Finite Numbers of Discontinuities.- 5. Displacement and Velocity Potentials.- 5.1 Directional Newton-Euler Equations.- 5.2 Set-Valued Force Laws.- 5.3 Scalar Potential Functions.- 5.4 On the Modeling of Force Laws.- 6. Representation of Scalar Force Laws.- 6.1 Decomposition into Unilateral Primitives.- 6.2 Variational Formulations and Upper Subderivatives.- 6.3 The Convex Case: Conjugate Potentials and Duality.- 6.4 Force Elements in Engineering Dynamics.- 7. Force Laws on Different Kinematic Levels.- 7.1 Continuity Properties of the Trajectories.- 7.2 Displacement Force Laws on Acceleration Level.- 7.3 Velocity Force Laws on Acceleration Level.- 8. Index Sets and LCP-Formulation.- 8.1 Index Sets.- 8.2 Formulation on Different Kinematic Levels.- 8.3 The Linear Complementarity Problem.- 8.4 The Dual Principle of Least Constraints.- 9. Principles in Dynamics.- 9.1 The Principle of Least Constraints.- 9.2 The Principle of Gauss.- 9.3 The Principle of Jourdain.- 9.4 The Principle of d'Alembert/Lagrange.- 9.5 Remarks on d'Alembert/Lagrange's Principle.- 10. Spatial Coulomb Friction.- 10.1 Geometry of Surfaces.- 10.2 Contact Kinematics.- 10.3 Kinetics.- 10.4 Contact Laws.- 10.5 Sliding Contacts.- 10.6 Friction Pyramid for Rolling Contacts.- 10.7 Friction Cones and NCP Formulations.- 10.8 A Differentiable NCP for Rolling Contacts.- 10.9 Example and Remarks.- 11. Velocity Jumps due to C0-Constraints.- 11.1 On Impacts in Mechanical Systems.- 11.2 Mechanical Model and Problem.- 11.3 Bilaterally Constrained Motion.- 11.4 Velocity Jump by Time-Scaling.- 11.5 Velocity Jump by Reflection.- 11.6 Reflections and Collisions - Remarks.- 12. Electropneumatic Drilling Machine.- 12.1 Mechanical Model.- 12.2 Simulations.- 13. Percussion Drilling Machine.- 13.1 Mechanical Model of the Drilling Machine.- 13.2 Mathematical Model for Non-Contact.- 13.3 The Contact Model.- 13.4 State Transitions.- 13.5 Results.- 14. Turbine Blade Damper.- 14.1 The Damper Model and the Non-Contact Case.- 14.2 Contact Kinematics of the Damping Device.- 14.3 Numerical Results.- 15. Concluding Remarks.- References.

Set-Valued Force Laws: Dynamics of Non-Smooth Systems

Snakes utilize irregularities in the terrain, such as rocks and vegetation, for faster and more efficient locomotion. This motivates the development of snake robots that actively use the terrain for locomotion, i.e., obstacle-aided locomotion. In order to accurately model and understand this phenomenon, this paper presents a novel nonsmooth (hybrid) mathematical model for wheel-less snake robots, which allows the snake robot to push against external obstacles apart from a flat ground. The framework of nonsmooth dynamics and convex analysis allows us to systematically and accurately incorporate both unilateral contact forces (from the obstacles) and isotropic friction forces based on Coulomb's law using set-valued force laws. The mathematical model is verified through experiments. In particular, a back-to-back comparison between numerical simulations and experimental results is presented. It is, furthermore, shown that the snake robot is able to move forward faster and more robustly by exploiting obstacles.

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Snake Robot Obstacle-Aided Locomotion: Modeling, Simulations, and Experiments

The main purpose of this paper is to present and discuss a methodology for a dynamic modeling and analysis of rigid multibody systems with translational clearance joints. The methodology is based on the non-smooth dynamics approach, in which the interaction of the elements that constitute a translational clearance joint is modeled with multiple frictional unilateral constraints. In the following, the most fundamental issues of the non-smooth dynamics theory are revised. The dynamics of rigid multibody systems are stated as an equality of measures, which are formulated at the velocity-impulse level. The equations of motion are complemented with constitutive laws for the normal and tangential directions. In this work, the unilateral constraints are described by a set-valued force law of the type of Signorini’s condition, while the frictional contacts are characterized by a set-valued force law of the type of Coulomb’s law for dry friction. The resulting contact-impact problem is formulated and solved as a linear complementarity problem, which is embedded in the Moreau time-stepping method. Finally, the classical slider-crank mechanism is considered as a demonstrative application example and numerical results are presented. The results obtained show that the existence of clearance joints in the modeling of multibody systems influences their dynamics response.

/pdf/modeling-and-analysis-of-rigid-multibody-systems-with-3u4x2tn9q0.pdf

Modeling and analysis of rigid multibody systems with translational clearance joints based on the nonsmooth dynamics approach

The aim of this paper is to develop a set-valued contact law for combined spatial Coulomb–Contensou friction, taking into account a normal friction torque (drilling friction) and spin. The set-valued Coulomb–Contensou friction law is derived from a non-smooth velocity pseudo potential. A higher-order Runge–Kutta time-stepping method is presented for the numerical simulation of rigid bodies with Coulomb–Contensou friction. The algebraic inclusion describing the contact problem is solved with an Augmented Lagrangian approach. The theory and numerical methods are applied to the Tippe-Top. The analysis and numerical results on the Tippe-Top illustrate the importance of Coulomb–Contensou friction for the dynamics of systems with friction.

http://www.mate.tue.nl/mate/pdfs/2823.pdf

Christoph Glocker

Papers

Multibody dynamics with unilateral contacts

Set-Valued Force Laws: Dynamics of Non-Smooth Systems

Snake Robot Obstacle-Aided Locomotion: Modeling, Simulations, and Experiments

Modeling and analysis of rigid multibody systems with translational clearance joints based on the nonsmooth dynamics approach

A set-valued force law for spatial Coulomb-Contensou friction