Dyn3d.jl

A 2d/3d rigid body dynamics solver

The main goal of this repository is to construct a rigid body-joint system and solve forward/backward dynamics problem on it. This package is functioned through:

• constructing 2d polygon shape rigid bodies and allow motion in 2d/3d space

• connecting bodies by joints which has 6 degree of freedoms for each

• solving motions on unconstrained(passive) degrees of freedom of joints

• solving forces on constrained degrees of freedom, allowing active motion

• plotting/making gif in Julia or making movies in Matlab

To solve a rigid body dynamics problem, this package express the dynamics using 6D spatial vector developed by Roy Featherstone[1]. The governing equations are formulated to fit in half explicit Runge-Kutta method on index-2 differential equations[2]. Constrained forces on joints are represented in Lagrange multiplier terms and solved together with motions of all degrees of freedom.

Based on the calculation of dynamical systems, Dyn3d.jl is also used to simulate fluid-structure interaction(FSI) problems together with package Whirl.jl for strongly coupled method. Notebook example is provided in notebook folder. Fully coupled method taking advantage of both Dyn3d.jl and Whirl.jl is implemented in package FSI.jl.

Installation

This package currently requires Julia 0.6. To install, simply download this Github repository, find the location of this repository expressed in Julia by

julia> Dyn3d_dir = Pkg.dir("Dyn3d")

and then setup a symbolic link in shell following

shell$ sudo ln -s actual_address Dyn3d_dir

The plots in this documentation are generated using Plots.jl. You might want to install that too to follow the examples.

If you have trouble in setting up the symbolic like to directory of Dyn3d.jl, a simple alternative solution is:

include(path*"Dyn3d.jl")

References