Tension mode

In the tension mode, the exponential softening law is assumed (see fig.(3)). The yield function has the following form

$$f_1( \mbox{\boldmath$\sigma$} ,\kappa_1) = \sigma-f_t(\kappa_1)$$ (57)

where the yield value $f_t$ is defined as

$$f_t=f_{t0}\exp\left(-\mbox{$\displaystyle\frac{f_{t0}}{G^I_f}$}\kappa_1\right)$$ (58)

Figure: Tensile behavior of proposed model ($f_t=0.2$ MPa, $G_f^I=0.018$ N/mm)

The $f_{t0}$ represents tensile strength of joint or interface; and $G^I_f$ is mode-I fracture energy. For the tension mode, the associated flow hypothesis is assumed.