OpenTissue::fem Namespace Reference

Namespaces
namespace	detail
Classes
class	Mesh
Functions
template<typename fem_mesh , typename matrix_type >
void	export_K (fem_mesh &mesh, matrix_type &bigK)
template<typename fem_mesh , typename real_type >
void	init (fem_mesh &mesh, real_type const &young, real_type const &poisson, real_type const &density, real_type const &c_yield, real_type const &c_creep, real_type const &c_max)
template<typename fem_mesh , typename real_type >
void	simulate (fem_mesh &mesh, real_type const &time_step, bool use_stiffness_warping)
template<typename node_iterator >
void	update_original_coord (node_iterator const &begin, node_iterator const &end)

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Function Documentation

template<typename fem_mesh , typename matrix_type >

void OpenTissue::fem::export_K	(	fem_mesh &	mesh,
		matrix_type &	bigK
	)			[inline]

Export Assembled Stiffness Matrix to a Sparse Matrix format (UBLAS style).

Parameters:

	mesh	The mesh containing the assembled K matrix (animate_warp shold have been invoked on priory to ensure this).
	bigK	Upon return holds the output values.

template<typename fem_mesh , typename real_type >

void OpenTissue::fem::init	(	fem_mesh &	mesh,
		real_type const &	young,
		real_type const &	poisson,
		real_type const &	density,
		real_type const &	c_yield,
		real_type const &	c_creep,
		real_type const &	c_max
	)			[inline]

Initialize Data Structres. Should be invoked at start-up before any calls to animate_warping.

This function assumes that mesh geometry have been set up prior to invokation (i.e. both world coord and orignial coord are initlized and the same).

This method initialized the model with the same material parameters. End user could write his or her own initilization method replacing the steps where young modules, poisson ratio and densities are assigned to the model.

Parameters:

	mesh
	young	Young Moduls, a value of 500000 seems work quite well.
	poisson	Poisson ration, a value of 0.33 seems work quite well.
	density	Mass density, a value of 1000 seems to work quite well.
	c_yield	Plastic yield.
	c_creep	Plastic creep.
	c_max	Plastic max.

template<typename fem_mesh , typename real_type >

void OpenTissue::fem::simulate	(	fem_mesh &	mesh,
		real_type const &	time_step,
		bool	use_stiffness_warping
	)			[inline]

Simulate. Note external forces must have been computed prior to invocation.

The dynamic equation has the following form (where u=x-x_0, and x' is derivative wrt. time)

M x'' + Cx' + K (x-x_0) = f_ext

This can be transformed to a system of 2x3n equations of first order derivative:

x' = v M v' = - C v - K (x-x_0) + f_ext

The semi-implicit Euler scheme approximates the above with:

x^(i+1) = x^i + t * v^(i+1) M v^(i+1) = M v^i + t ( - C v^(i+1) - K ( x^i - x_0 ) + f^i_ext

This is solved using implicit integration.

Parameters:

	mesh
	time_step
	use_stiffness_warping

template<typename node_iterator >

void OpenTissue::fem::update_original_coord	(	node_iterator const &	begin,
		node_iterator const &	end
	)			[inline]

Update original coords with world coords.

Note: This completely destroys any prior initialization of force offset (f0 in stiffness elements initialization). Therefore these must be re-initialized after invocation of this function.

Parameters:

	begin
	end