Specification of stress-strain relation of pipe material (Input Table)

Data description/conditions:

MATREF:

Reference name of material data

Unique name in list

Rm:

Ultimate tensile strength

> 0. / Undefined

SIGEPS:

Type of stress-strain relation (diagram)

Undefined / Prescribed names: Bilinear, Ductile, DS-Hardening, Cyclic

(If Undefined, the Bilinear diagram is applied in case of material non linear calculations.
Bilinear = Bilinear stress-strain relation
Ductile = Ductile stress-strain relation
DS-Hardening = Ductile stress-strain relation with Strain Hardening
Cyclic = Stress-strain relation under cyclic loading
See below for further description.)

K-VALUE:

(cyclic) hardening coefficient

> 0. if SIGEPS = CYCLIC / Undefined

N-VALUE:

(cyclic) hardening exponent

> 0. if SIGEPS = CYCLIC / Undefined

CHKEPS:

Check strain of pipe material

> 0. / Undefined

(If UNDEFINED, the value is set to 7 or 5 permil (see NEN 3650). This strain is considered to be an allowable strain in case of material non-linear analysis. If exceeded, a warning is given.)

 

The diagram for the stress-strain relation can be described approximately by an analytical function, for cyclic loading by the equation:

e = s/E + (s/K)**(1/N)

where:        e = strain
         s = stress
         E = Young's modulus
         K = hardening coefficient
         N = hardening exponent

Built-in stress-strain relations:

 

BILIN Stress-Strain diagram

DUC Stress-Strain diagram

DSH Stress-Strain diagram

Strain /
Yield-strain

Stress /
Yield-stress

Strain /
Yield-strain

Stress /
Yield-stress

Strain /
Yield-strain

Stress /
Yield-stress

0.000

0.000

0.000

0.000

0.667

0.667

1.000

1.000

0.450

0.450

0.926

0.800

~

1.000

0.650

0.600

1.111

0.850

 

 

0.830

0.700

1.370

0.900

 

 

1.080

0.800

1.667

0.940

 

 

1.300

0.850

1.889

0.960

 

 

1.700

0.900

2.000

0.970

 

 

2.300

0.950

2.259

0.980

 

 

2.830

0.980

2.630

0.990

 

 

3.400

1.000

3.370

1.000

 

 

~

1.000

9.000

1.001

 

 

 

 

18.000

1.167

 

 

 

 

27.000

1.267

 

 

 

 

36.000

1.325

 

 

 

 

45.000

1.358

 

 

 

 

54.000

1.375

 

 

 

 

63.000

1.390

 

 

 

 

~

1.390

 

Normalized Stress-Strain diagram

 

The above diagram shows the various built in (dimensionless) stress-strain relations (yield-strain = Re/Emod). The following diagram shows various stress-strain relations for a specific situation:

 

Stress-Strain diagram

 

The Hutchinson & Miles and Ramberg & Osgood curves are frequently occurring stress-strain relations in literature.
They can be modeled in Ple4Win too by using the 'Cyclic' option with the appropriate parameters K' en n'.
The MATCON curve shows the stress-strain relation of the material used for an in-plane bending test with soil pressure simulation by TNO.

 


H310181, last changed: 6/26/2018

See also:

Table description

Table error description