This option in the Material New/Modify panel lets you change cutoff values that are used by Autodyn. The following fields are available:

**Maximum Expansion**This is used to limit the maximum expansion of a cell. If the expansion of a cell exceeds this maximum value, it is reduced to this value.

**Minimum Density Factor (Euler)**This cutoff prevents floating point errors due to small quantities of mass in an Euler cell. It is used to ensure that the minimum amount of a particular materials mass in a cell is never less than

{density cutoff} * {reference density} * {cell volume}

if {density cutoff} > 0.0

or

- {density cutoff} * {cell volume}

if the {density cutoff} < 0.0

The default value of 1.0E-4 should be adequate for most problems. You might need to change this value if you have a material which expands to well below its reference density (e.g. high explosive expanding into a vacuum or air).

**Minimum Density Factor (SPH) and Maximum Density Factor (SPH)**These options let you define minimum and maximum density values for the SPH regions of your problem.

**Minimum Soundspeed**This is used to help avoid division by zero in the time step calculation and avoid the possibility of taking the square root of a negative value of C2. If the computed soundspeed is less than this cutoff, it is set equal to the cutoff value.

**Maximum Soundspeed (SPH)**This is used to limit the maximum soundspeed for SPH. If the soundspeed exceeds this maximum value, it is reduced to this value.

**Maximum Temperature**This is used to limit the maximum temperature within a cell. If the temperature within a cell exceeds this maximum value, it is reduced to this value.