Specification of stressstrain 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 stressstrain relation (diagram)
Undefined / Prescribed names: Bilinear, Ductile, DSHardening, Cyclic
(If Undefined, the Bilinear diagram is applied in case of material non linear calculations.
Bilinear = Bilinear stressstrain relation
Ductile = Ductile stressstrain relation
DSHardening = Ductile stressstrain relation with Strain Hardening
Cyclic = Stressstrain relation under cyclic loading
See below for further description.)
KVALUE:
(cyclic) hardening coefficient
> 0. if SIGEPS = CYCLIC / Undefined
NVALUE:
(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 nonlinear analysis. If exceeded, a warning is given.)
The diagram for the stressstrain 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
Builtin stressstrain relations:
BILIN StressStrain diagram 
DUC StressStrain diagram 
DSH StressStrain diagram 

Strain / 
Stress / 
Strain / 
Stress / 
Strain / 
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 
The above diagram shows the various built in (dimensionless) stressstrain relations (yieldstrain = Re/Emod). The following diagram shows various stressstrain relations for a specific situation:
The Hutchinson & Miles and Ramberg & Osgood curves are frequently occurring stressstrain 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 stressstrain relation of the material used for an inplane bending test with soil pressure simulation by TNO.
H310181, last changed: 6/26/2018
See also: