Stress sign convention

[dineshp1]

Hi,
Which stress sign convention is used in the Porous Flow module: compressive stresses as positive or -ve?

Thanks,
Dinesh P

[WilkAndy]

It is the same convention as TensorMechanics, which is:

• a positive strain is extensional, which (usually) results from a positive (tensile) stress;
• a negative strain is compressional, which (usually) results from a negative (compressive) stress

[dineshp1]

Thank you much for the quick reply.

[jmeier]

Please allow me ask more in detail:

• Compressive porepressures (e.g. below a free water table) have a positive sign?
• Suction is represented by porepressures having a negative sign?