# Subspring Network Model Properties

The properties of the Subspring Network Model are shown below for reference. More detailed information regarding these properties is presented in the model description.

Note

Some properties are read-only; these are indicated with *(r)* in the right margin.

- dp_force v
\(\mathbf{F^d}_{sub}\) - dashpot force in units force. Expressed in the contact plane coordinate system. The returned value is the total dashpot force if sn_index is 0, or the corresponding subcontact dashpot force otherwise.

- dp_mode i
\(M_d\) - dashpot mode with default value 0.

- dp_nratio f
\(\beta_n\) - normal critical damping ratio with default value 0.0.

- dp_sratio f
\(\beta_s\) - shear critical damping ratio with default value 0.0.

- fric f
\(\mu\) - friction coefficient with default value 0.0. If zero, \(\mu\) will be set if the bond friction angle \(\phi\) is specified.

- kn f
\(k_n\) - normal stiffness in units stress/disp/area, with default value 0.0.

- kratio f (r)
\(\kappa^*\) - normal-to-shear stiffness ratio.

- krot v
\(k_r\) - rotational stiffness in units stress/disp/area, with default value \(\mathbf{0}\). In 2D this is a floating point value.

- ks f
\(k_s\) - shear stiffness in units stress/disp/area, with default value 0.0.

- rgap f
\(g_r\) - reference gap in units length with default value 0.0.

- sn_area f (r)
\(A\) - area of the contact.

- sn_cntconv i
convergence count to check if the Poisson correction should be computed with default value -1 meaning that no check will occur.

- sn_coh f
\(\sigma_c\) - bond cohesive strength in units stress with default value 0.0.

- sn_cohdc f
critical slip distance (i.e., for degradation of shear strength as a function of slip) in units distance with default value 0.0.

- sn_cohtab v
cohesive strength multiplier (\(x\)-component) as a function of slip (\(y\)-component). Use sn_tabpos to set the table position when retrieving a value.

- sn_cohres f
residual cohesive strength in units stress with default value 0.0.

- sn_conv f
convergence value to check if the Poisson correction should be computed with default value 1000.

- sn_dil f
dilation angle in degrees with default value 0.0.

- sn_dilzero f
shear displacement where dilation stops in units distance with default value infinity.

- sn_fa f
\(\phi\) - bond friction angle in units degrees with default value 0.0. If specified and the friction coefficient \(\mu=0\) then it is set to this value.

- sn_force v
\(\mathbf{F}_{sub}\) - linear force in units force with default value \(\mathbf{0}\). Expressed in the contact plane coordinate system. The returned value is the total force if sn_index is 0, or the corresponding subcontact force otherwise.

- sn_gap f
\(g_{sub}\) - tracked gap. The returned value is the maximum gap if sn_index is 0, or the corresponding subcontact gap otherwise.

- sn_heal i
healing mode with default value 0 (no healing). If set to 1 then the strength goes back to

`sn_coh`

when sliding ceases.

- sn_index i
index used to query subcontacts properties. The index can range from 0 (the default) to {2 in 2D; 3 in 3D}.

- sn_moment v
\(\mathbf{M}_{sub}\) - moment. Expressed in the contact plane coordinate system. The returned value is the total moment if sn_index is 0, or the corresponding subcontact moment otherwise.

- sn_non_diag i
off-diagonal computation mode with default 1 (off-diagonal Poisson correction). Off-diagonal terms are not utilized when set to 0.

- sn_pois f
Poisson ratio with default value 0.0.

- sn_pois_force v (r)
Poisson force correction in units force. Expressed in the contact plane coordinate system. The returned value is the total fictitious force if sn_index is 0, or the corresponding subcontact fictitious force otherwise.

- sn_porp f
\(P_p\) - Pore pressure in units stress. Positive pore pressure reduces the effective normal stress for failure computations.

- sn_sdisp f
accumulated shear displacement magnitude in units distance with default value 0. The returned value is the maximum subcontact slip if sn_index is 0, or the corresponding subcontact slip otherwise.

- sn_slip b (r)
\(s_{sub}\) - slip state. The returned value is true if any subcontact is slipping if sn_index is 0, or the corresponding subcontact slip state otherwise.

- sn_shear f (r)
\(\tau_{c}\) - bond shear strength in units stress.

- sn_state i (r)
\(B_{sub}\) - bond state. The returned value is the accumulated state of each subcontact if sn_index is 0, or the corresponding subcontact state otherwise.

- sn_states s (r)
bond state string. The returned value is the accumulated state of each subcontact if sn_index is 0, or the corresponding subcontact state otherwise.

- sn_tabpos i
position in the cohesion table.

- sn_tau f (r)
\(\tau\) - bond shear stress at bond periphery in units stress.

- sn_ten f
\(\sigma_c\) - bond tensile strength in units stress with default value 0.0.

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