# Global Time Step

The global time step (GTS) method can be used to calculate the time step of a model based on the natural frequency of the model.

For some models the global time step method results in a higher time step when
compared to calculating the time step based on each element or node. An iterative
algorithm is used to calculate the global time step which is more expensive than
calculating the element or nodal time step. Therefore, the global time step
calculation is done every 20 cycles by default.

- /DT/GLOB/Iflag
- $\text{\Delta}{T}_{sca}$

If `Iflag`=1, insert the next line

`Tol_GTS`
`Ncycles`

Where,

- $\text{\Delta}{T}_{sca}$
- Scale factor for the element time step
`Tol_GTS`- Convergence tolerance for the iterative algorithm
`Ncycles`- Number cycles between the calculation of the global time step

The global time method is useful in models without a large change in stiffness such as drop test simulations.

The Global Time Step option is available for the following features:

- Solid elements: /TETRA4, /TETRA10, hexa with the flags below
- /PROP/SOLID:
`I`_{solid}= 1 (Belytschko), 14 (HA8), 17 (H8C), 24 (HEPH) and 16 (20-noded) - Shell elements:
`I`_{shell}= 1 (Belytschko-Tsay), 12 (Batoz), and 24 (HEPH) - Truss element
- Beam element
- Contact interfaces: TYPE7, TYPE24 (without edge-to-edge option), and TYPE2
with
`Spot`_{flag}=25 and 27