Table of Contents

BINDS

Description

Constitutive law for BINDS elements.

The model

This law is used to enforce non-linear constraints between several degrees of freedom of the discretized structure.

Files

Prepro: LBINDS.F

Availability

Plane stress state YES
Plane strain state YES
Axisymmetric state YES
3D state YES
Generalized plane state YES

Input file

Parameters defining the type of constitutive law

Line 1 (2I5, 60A1)
ILLaw number
ITYPE 30
COMMENT Any comment (up to 60 characters) that will be reproduced on the output listing

Integer parameters

Line 1 (5I5)
LTYP1 = 1 to enforce elastic constraints
= 2 to enforce elasto-plastic constraints
= 3 to enforce bi-linear elastic constraints
NALPHA number of different αi coefficients in the constraint equation (including α0)
ICODE = 0 if the constraint equation enforces a rigid body mode
= 1 else
NDEF Number of times of definition for α sets
IBEND = 0 generally
= 1 if management of bending/unbending thanks to generalized plane strain state

Real parameters

1. LTYP1 = 1

Line 1 (7G10.0) - repeated as many times as necessary
ALPHA(I)
I = 1,NALPHA		 The αi coefficients of the constraint equation
Line n=round(NALPHA/7) (G10.0)
TRACEK1 = the elastic stiffness of the constraint

2. LTYP1 = 2

Line 1 (7G10.0) - repeated as many times as necessary
ALPHA(I)
I = 1,NALPHA		 The αi coefficients of the constraint equation
Line n=round(NALPHA/7) (3G10.0)
TRACE(1)K1 = the elastic stiffness of the constraint
TRACE(2)K2 = the tangent elasto-plastic stiffness of the constraint
LH1The elastic limit of the constraint

3. LTYP1 = 3

Line 1 (7G10.0) - repeated as many times as necessary
ALPHA(I)
I = 1,NALPHA		 The αi coefficients of the constraint equation
Line n=round(NALPHA/7) (2G10.0)
TRACE(1)K1 = the elastic stiffness in tension
TRACE(2)K2 = the elastic stiffness in compression

Remarks

  1. if IBEND = 0 : coefficient α0 is multiplied by DMULT during the simulation
  2. if IBEND = 1 : in generalised plane strain state, thickness is given by: e(x,y) = A + B.x + C.y
    α1 is the coefficient of “A” and it must be equal to the curve in the OXZ plane
    α2 is the coefficient of “B” and it must be equal to 1.0
    α0 is automatically computed

Stresses

Number of stresses

1

Meaning

SIG(1)The generalized force necessary to enforce the constraint.

State variables

Number of state variables

List of state variables

1. LTYP1 = 1 (elastic constraint)

Q(1) = 0 (meaningless)
Q(6) = strain energy

2. LTYP1 = 2 (elasto-plastic constraint)

Q(1)current yield limit ; its initial value is LH1
Q(2) = 0 if the current state is elastic
= 1 if the current state is elasto-plastic.
Q(6) strain energy

3. LTYP1 = 3 (bi-linear elastic constraint)

Q(1) = 0 if the current state is in tension
= 1 if the current state is in compression