mbs_modal.c File Reference

#include "mbs_modal.h"
#include "mbs_linalg.h"
#include "mbs_errors_names.h"
#include "math.h"
#include "mbs_statespace.h"
#include "mbs_message.h"
#include "mbs_check.h"
#include "mbs_trigo.h"

Macros
#define	_USE_MATH_DEFINES

Functions
MbsModal *	mbs_new_modal (MbsData *s)
	Create a new modal structure. More...
MbsModal *	mbs_new_modal_aux (MbsData *s, MbsAux *mbs_aux)
	Create a new modal structure. More...
int	mbs_run_modal (MbsModal *mo, MbsData *s)
	Run the Modal Analysis. More...
int	mbs_modal_init (MbsModal *mo, MbsData *s)
	Initialize the Modal structure variables. More...
int	mbs_modal_loop (MbsModal *mo, MbsData *s)
	Perform the Modal analysis. More...
int	mbs_modal_finish (MbsModal *mo, MbsData *s)
	Set Modal flag to done in MbsData structure and save the modal analysis. More...
void	mbs_delete_modal (MbsModal *mo, MbsData *s)
	Free the MbsModal structure (pointers table, ...) More...
int	mbs_modal_norm_evec (double **mat_r, double **mat_phi, int nqu, int Nux, int ind, double *evec_r, double *evec_phi)
	Additional function necessary for modal analysis post-process. More...
int	mbs_modal_save_result (MbsModal *mo, MbsData *s, char *filename)
	Write the modal analysis results (eigenmode, eigenfrequencies, mode type, ...) into a ASCII text file. More...
int	mbs_modal_save_anim (MbsModal *mo, MbsData *s, char *filepath)
	Save the modes animations in the MbSysPad format. More...

Detailed Description

This file implements the functions of the modal module in C.

Creation date: 26/11/2015

Author

Quentin Docquier (based on the work of Aubain Verle and Paul Fisette)

(c) Universite catholique de Louvain

Macro Definition Documentation

_USE_MATH_DEFINES

#define _USE_MATH_DEFINES

Function Documentation

mbs_delete_modal()

void mbs_delete_modal	(	MbsModal *	mo,
		MbsData *	s
	)

Free the MbsModal structure (pointers table, ...)

The MbsModalOptions (MbsModal::options), the MbsLpk (MbsModal::lpk) and MbsAux (MbsModal::aux) structures are also freed.

Parameters

[in,out]	mo	The MbsModal to be freed.
[in]	s	The MbsData structure related to the parameter mo.

mbs_modal_finish()

int mbs_modal_finish	(	MbsModal *	mo,
		MbsData *	s
	)

Set Modal flag to done in MbsData structure and save the modal analysis.

The Modal analysis results are saved in .txt file:

• the A matrix
• the modal analysis (with UNSORTED MODES !!!)
• the mode animation (to read with the MBSysPad)

Parameters

[in,out]	mo	the MbsModal to be saved.
[in]	s	the MbsData structure related to the parameter mo.

Returns

Error status, <0 in case of failure.

mbs_modal_init()

int mbs_modal_init	(	MbsModal *	mo,
		MbsData *	s
	)

Initialize the Modal structure variables.

It allocates the memory based on the number of independant (nqu) variables in the MBS system

Parameters

[in,out]	mo	the MbsModal to be run
[in]	s	the MbsData structure of the model for which the modal analysis is computed

Returns

Error status, <0 in case of failure.

mbs_modal_loop()

int mbs_modal_loop	(	MbsModal *	mo,
		MbsData *	s
	)

Perform the Modal analysis.

The modal analysis requires the following operations:

1. Linearization of the Rr term into the stiffness matrix Kr, and the damping matrix Gr (see Basics)
2. Compution of matrix A (see basics)
3. Modal analysis (through gcl libraries)
4. Post processing:
   • 4.1. EigenModes
   • 4.2. EigenModes ordering by types and frequencies

Based on the solvepk algorithm (see Numerics)

Parameters

[in,out]	mo	the MbsModal to be run
[in]	s	the MbsData structure of the model for which the modal analysis is computed

Returns

Error status, <0 in case of failure.

mbs_modal_norm_evec()

int mbs_modal_norm_evec	(	double **	mat_r,
		double **	mat_phi,
		int	nqu,
		int	Nux,
		int	ind,
		double *	evec_r,
		double *	evec_phi
	)

Additional function necessary for modal analysis post-process.

It allows to normalize the position nqu part of the eigenvector based on the position part of the vector (vel is ommited). To avoid complication this features is only available when Nux=0 (because for multiphysics, order of magnitude can be different depending on the units chosen...).

Parameters

[in]	mat_r	norm of the eigen vectors.
[in]	mat_phi	phase of the eigen vectors.
[in]	nqu	number of independant joints.
[in]	Nux	number of extra ODE variables.
[in]	ind	index of the eigen value processed.
[out]	evec_r	Norm of the eigen vector associated to the mode.
[out]	evec_phi	Phase of the eigen vector associated to the mode.

Returns

0

mbs_modal_save_anim()

int mbs_modal_save_anim	(	MbsModal *	mbs_modal,
		MbsData *	s,
		char *	filepath
	)

Save the modes animations in the MbSysPad format.

Parameters

[in]	mbs_modal	the MbsModal to be run
[in]	s	the MbsData structure of the model for which the modal analysis is computed
[in]	filepath	the path and basename of the file to write.

Returns

Error status, <0 in case of failure.

mbs_modal_save_result()

int mbs_modal_save_result	(	MbsModal *	mbs_modal,
		MbsData *	s,
		char *	filename
	)

Write the modal analysis results (eigenmode, eigenfrequencies, mode type, ...) into a ASCII text file.

The modes are not sorted.

Parameters

[in]	mbs_modal	the MbsModal to be run
[in]	s	the MbsData structure of the model for which the modal analysis is computed
[in]	filename	the path and full name of the file to write.

Returns

Error status, <0 in case of failure.

mbs_new_modal()

MbsModal* mbs_new_modal

(

MbsData *

mbs_data

)

Create a new modal structure.

This function also initialize the options structures and the MbsAux for storing computational info during simulation.

mbs_data the data structure of the model for which the modal analysis will be computed

mbs_new_modal_aux()

MbsModal* mbs_new_modal_aux	(	MbsData *	s,
		MbsAux *	mbs_aux
	)

Create a new modal structure.

This function also initialize the options structures. A pointer to the given MbsAux structure is kept by the returned structure.

mbs_data the data structure of the model for which the modal analysis will be computed

mbs_run_modal()

int mbs_run_modal	(	MbsModal *	mo,
		MbsData *	s
	)

Run the Modal Analysis.

The modal analysis consists in the following function

• mbs_modal_init()
• mbs_modal_loop()
• mbs_modal_finish()

The MbsData structure associated should not be modified if the process success.

Parameters

[in,out]	mo	the MbsModal to be run
[in]	s	the MbsData structure of the model for which the modal analysis is computed

Returns

Error status, <0 in case of failure.