Course 23 | Advanced Engineering Methods

Multibody Dynamics and Mechanical-System Simulation

Model connected rigid bodies with joints and forces, then build and integrate their equations of motion into checked mechanical-system simulations.

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Course snapshot

Purpose
Multibody dynamics teaches how to turn a mechanism, vehicle, or robot into constrained equations of motion and simulate its motion over time.
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Content status
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How to study this course

  1. Define bodies, joints, and forces
  2. Choose generalized coordinates
  3. Write the constraint equations
  4. Assemble the equations of motion
  5. Integrate the motion in time
  6. Check energy, constraints, and a hand estimate
01

How this course is designed

Model before you solve

Every study starts by naming the bodies, joints, and forces and counting the degrees of freedom. That count sizes the problem and tells you how many inputs and initial conditions a simulation needs, before a single equation is written.

Grounded in Wittenburg

The course follows Wittenburg, Dynamics of Multibody Systems, from rigid-body kinematics through the general equations of motion to impacts, so the vocabulary matches the formalism used in real multibody software.

Every result is checkable

Each module ends in a quantity: a degree-of-freedom count, a constraint Jacobian, a Lagrange multiplier, a stable time step, or a conserved energy, the evidence that turns a running simulation into a defensible result.

02

The 10 modules

01 | Module

Introduction to Multibody Systems and Simulation

Bodies, joints, and forces, tree and closed-loop topology, and the degree-of-freedom count.

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02 | Module

Rigid-Body Kinematics: Position and Orientation

Rotation matrices, Euler and Bryan angles, angular velocity, and Euler parameters.

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03 | Module

Generalized Coordinates and Degrees of Freedom

Minimal coordinates and the Grubler-Kutzbach mobility criterion in the plane and in space.

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04 | Module

Kinematic Constraints and Joints

Holonomic and nonholonomic constraints, the Jacobian, and velocity and acceleration analysis.

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05 | Module

Mass, Inertia, and Momentum

The inertia tensor, the parallel-axis theorem, kinetic energy, and angular momentum.

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06 | Module

Newton-Euler Equations of Motion

Force to acceleration for the mass center and Euler’s equations for three-dimensional spin.

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07 | Module

Lagrangian Dynamics and Virtual Work

Energy methods, generalized forces by virtual work, and Lagrange multipliers.

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08 | Module

Constrained Equations of Motion (DAEs)

The augmented system, multipliers as reactions, differential index, and Baumgarte stabilization.

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09 | Module

Numerical Simulation of Multibody Systems

State-space form, explicit and implicit integrators, DAE solvers, and choosing a time step.

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10 | Module

Impacts, Contact, and Simulation Validation

Impulsive dynamics and restitution, and validating a model by momentum, energy, and constraints.

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