[MBDyn-users] Questions on ' relative orientation matrix' in MBDyn

xiaoli zhang zhangxl.bitase at yahoo.com
Sat Sep 16 03:48:05 CEST 2017


Dear prof. P.Masarati,Thank you very much for your answer! I am sorry for not making the problem clear. The complete description of the example is as follow:---------------------------------------------------------
Here is a a rotating plate amounted on right side tip of a rigid beam, the left side of beam is connect to ground by two torsion springs in pitch and yaw direction, with the global coordinate Y axis coincide with pith axis, Z axis coincide with yaw axis, and stiffness constants ky and kz, respectively:
In the MBDyn model I use a Cardano hinge and a Deformable hinge to model the torsion spring in left tip, and a axial rotation hinge to model the rotation in the right hand.
the result didnot converge.
---------------------------------------------------------
                   \     /     | z
                    \   /      |
 |ground  beam       \ /       |
 O---------O----------O  plate |______x
 |                   / \
                    /   \
                   /     \
O---Stands for structural node;----------------------------------------------------------# Example.set

#    Coordinate NO.
set: integer ground = 10;
set: integer beam = 20;
set: integer beam_spring = 30;
set: integer beam_cardano = 40;
set: integer plate = 50;

set: integer RF_ground = 1000;
set: integer RF_beam = 2000;
set: integer RF_plate = 3000;

#    General data
set: real omega = 1500.0/60.0*2*3.14;

set: real kx = 0;
set: real ky = 100;
set: real kz = 200;


set: real l = 1;
set: real mass_beam = 10.0;
set: real Ixx_beam = 0.5;
set: real Iyy_beam = 1/12.0*mass_beam*l^2;
set: real Izz_beam = 1/12.0*mass_beam*l^2;

set: real R = 0.25;
set: real mass_plate = 100;
set: real Ixx_plate = 1/2.0*mass_plate*R^2;
set: real Iyy_plate = 1/4.0*mass_plate*R^2;
set: real Izz_plate = 1/4.0*mass_plate*R^2;----------------------------------------------------
# Example.ref
#Gound Frame

reference: RF_ground,
    reference, global, null,
    reference, global, eye,
    reference, global, null,
    reference, global, null;

#Beam Frame

reference: RF_beam,
    reference, RF_ground, l/2,0.,0.,
    reference, RF_ground, eye,
    reference, RF_ground, null,
    reference, RF_ground, null;

#Plate Frame

reference: RF_plate,
    reference, RF_beam, l/2,0.,0.,
    reference, RF_beam, eye,
    reference, RF_beam, null,
    reference, RF_beam, omega, 0., 0.;----------------------------------------# Example.mbd
# Parameters preset
include: "Example.set";

#Coordinate Frame Define
include: "Example.ref";

begin: data;
    problem: initial value;
end: data;

begin: initial value;
    initial time: 0.;
    final time: 0.1;
    time step: 0.02;

    tolerance: 1e-5;
    max iterations: 10;

    derivatives tolerance: 10e0;
    derivatives max iterations: 200;
    derivatives coefficient: 1e-3;
    
    linear solver: naive, colamd, mt, 1, pivot factor, 1e-8;
    nonlinear solver: newton raphson, modified, 10;
    eigenanalysis: 50., parameter, 1.e-6,
        output matrices, output eigenvectors;
    method: bdf;
    output: residual;
end: initial value;

begin: control data;
    structural nodes: 
        +1    #ground
        +1    #beam
        +1    #plate
        ;
    joints: 
        +1    #ground
        +1    #cardano joint constraint between beam and ground
        +1    #deformable joint between beam and ground
        +1    #plate rotation hinge
        ;
    rigid bodies:
        +1    #beam
        +1    #plate
        ;
    print: equation description;
    print: node connection;
end: control data;

begin: nodes;
    structural: ground, static,
        reference, RF_ground, null,
        reference, RF_ground, eye,
        reference, RF_ground, null,
        reference, RF_ground, null;

    structural: beam, dynamic,
        reference, RF_beam, null,
        reference, RF_beam, eye,
        reference, RF_beam, null,
        reference, RF_beam, null;

    structural: plate, dynamic,
        reference, RF_plate, null,
        reference, RF_plate, eye,
        reference, RF_plate, null,
        reference, RF_plate, null;
end: nodes;

begin: elements;
    joint: ground, clamp, ground, node, node;
    
    joint: beam_spring, deformable hinge,
        ground, position, reference, RF_ground, null,
                orientation, reference, RF_ground, eye,
        beam, position, reference, RF_ground, null,
                 orientation, reference, RF_ground, eye,
    linear elastic generic,
        sym, 0, 0., 0.,
               -ky, 0.,
                   -kz; 
    joint: beam_cardano, cardano hinge,
        ground, position, reference, RF_ground, null,
                orientation, reference, RF_ground, eye,
        beam, position, reference, RF_ground, null,
                orientation, reference, RF_ground, eye;
    joint: plate, axial rotation,
        beam, position, reference, RF_plate, null,
                 orientation, reference, RF_beam,
                        1, 0., 0., -1.,
                        3, 1., 0., 0.,
        plate, position, reference, RF_plate, null,
                   orientation, reference, RF_plate,
                        1, 0., 0., -1.,
                        3, 1., 0., 0.,
        const, omega;
    body: beam, beam,
            mass_beam, 
            reference, RF_beam, null,
            diag,
                Ixx_beam,
                Iyy_beam,
                Izz_beam;
    body: plate, plate,
            mass_plate,
            reference, RF_plate, null,
            diag,
                Ixx_plate,
                Iyy_plate,
                Izz_plate;
end: elements;------------------------------------------------# the last iteration 

Residual(1:10) t=0.02 dt=0.02
Eq         1:                    0 StructNode(10): force equilibrium Fx
Eq         2:                    0 StructNode(10): force equilibrium Fy
Eq         3:                    0 StructNode(10): force equilibrium Fz
Eq         4:                    0 StructNode(10): moment equilibrium Mx
Eq         5:                    0 StructNode(10): moment equilibrium My
Eq         6:                    0 StructNode(10): moment equilibrium Mz
Eq         7:                    0 StructNode(20): momentum definition Bx
Eq         8:                    0 StructNode(20): momentum definition By
Eq         9:                    0 StructNode(20): momentum definition Bz
Eq        10:                    0 StructNode(20): momenta moment definition Gx
Eq        11:                    0 StructNode(20): momenta moment definition Gy
Eq        12:                    0 StructNode(20): momenta moment definition Gz
Eq        13:                    0 StructNode(20): force equilibrium Fx
Eq        14:                    0 StructNode(20): force equilibrium Fy
Eq        15:                    0 StructNode(20): force equilibrium Fz
Eq        16:                    0 StructNode(20): moment equilibrium Mx
Eq        17:                    0 StructNode(20): moment equilibrium My
Eq        18:                    0 StructNode(20): moment equilibrium Mz
Eq        19:                    0 StructNode(50): momentum definition Bx
Eq        20:                    0 StructNode(50): momentum definition By
Eq        21:                    0 StructNode(50): momentum definition Bz
Eq        22:              42.6781 StructNode(50): momenta moment definition Gx
Eq        23:                    0 StructNode(50): momenta moment definition Gy
Eq        24:                    0 StructNode(50): momenta moment definition Gz
Eq        25:                    0 StructNode(50): force equilibrium Fx
Eq        26:                    0 StructNode(50): force equilibrium Fy
Eq        27:                    0 StructNode(50): force equilibrium Fz
Eq        28:                    0 StructNode(50): moment equilibrium Mx
Eq        29:                    0 StructNode(50): moment equilibrium My
Eq        30:                    0 StructNode(50): moment equilibrium Mz
Eq        31:                    0 ClampJoint(10): position constraint Px
Eq        32:                    0 ClampJoint(10): position constraint Py
Eq        33:                    0 ClampJoint(10): position constraint Pz
Eq        34:                    0 ClampJoint(10): orientation constraint thetax
Eq        35:                    0 ClampJoint(10): orientation constraint thetay
Eq        36:                    0 ClampJoint(10): orientation constraint thetaz
Eq        37:                    0 Joint(40): equation(1)
Eq        38:                    0 Joint(40): equation(2)
Eq        39:                    0 Joint(40): equation(3)
Eq        40:                    0 Joint(40): equation(4)
Eq        41:                    0 AxialRotationJoint(50): position constraint Px
Eq        42:                    0 AxialRotationJoint(50): position constraint Py
Eq        43:                    0 AxialRotationJoint(50): position constraint Pz
Eq        44:                    0 AxialRotationJoint(50): orientation constraint gx
Eq        45:                    0 AxialRotationJoint(50): orientation constraint gy
Eq        46:               13.657 AxialRotationJoint(50): angular velocity constraint wz
Max iterations number 10 has been reached during first step, Time=0; TimeStep=0.02 cannot be reduced further; aborting...
An error occurred during the execution of MBDyn; aborting... 
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