If at the current time increment, $\mathrm{\Delta}t$,

$$\mathrm{\Delta}t{\left(\frac{{S}^{J}}{\mathrm{\Delta}t}\right)}_{i}<{W}_{G}{T}^{J}$$

for all J in each of ${I}_{T}$ consecutive increments, i, and if no cut-back has occurred within those increments because of nonlinearity, the next time increment will be increased to

$$min\left({D}_{G}\mathrm{\Delta}{t}_{p},{D}_{M}\mathrm{\Delta}t\right).$$

You can define the values of ${I}_{T}$, ${W}_{G}$, and ${D}_{G}$. By default, ${I}_{T}$ = 3, ${W}_{G}$ = 0.75, and ${D}_{G}$ = 0.8. $\mathrm{\Delta}{t}_{p}$ is the proposed new time increment, which is defined as

$$\mathrm{\Delta}{t}_{p}=\left(\frac{{T}^{J}}{{S}^{J}/\mathrm{\Delta}t}\right)$$

for transient heat transfer and transient mass diffusion problems and which is defined as

$$\mathrm{\Delta}{t}_{p}={I}_{T}\left(\frac{{T}^{J}}{{\sum}_{i=1}^{{I}_{T}}{\left({S}^{J}/\mathrm{\Delta}t\right)}_{i}}\right)$$

for other transient problems.

A limit, ${D}_{M}$, is placed on the time increment increase factor. The default value of ${D}_{M}$ depends on the type of analysis:

${D}_{M}^{dyn}$ = 1.25 for dynamic analysis

${D}_{M}^{diff}$ = 2.0 for diffusion-dominated processes: creep, transient heat transfer, coupled temperature-displacement, soils consolidation, and transient mass diffusion

${D}_{M}$ = 1.5 for all other cases

You can redefine ${D}_{M}$ for each analysis type.

If the problem is nonlinear, the time increment may be restricted by the rate of convergence of the nonlinear equations. The time incrementation controls used with nonlinear problems are described in Convergence criteria for nonlinear problems.

Input File Usage

CONTROLS, PARAMETERS=TIME INCREMENTATION
, , , , , , , , , ${I}_{T}$
, , , , , , , ${W}_{G}$
${D}_{G}$, ${D}_{M}$, ${D}_{M}^{dyn}$, ${D}_{M}^{diff}$

Abaqus/CAE Usage

Step module: : toggle on Specify: Time Incrementation; click More to see additional data tables