Nonlinear stress-strain curve, true or engineering strain?

SOFiSTiK Teddy
1

Hi,
I want to create a custom stress-strain curve using the SSLA command. Is the input true strain or engineering strain? AQUA manual doesn’t specify this.
Best regards
Joachim

2

For anyone interested: it’s engineering stresses and strains. I did a simple materially nonlinear calculation with a single quad element and the results were the same as with a handcalculation for a constant section (no necking).
I used SSLA calc in AQUA and in ASE I used SYST prob nonl nmat yes and NSTR ksv cal.