As it is a joint component, there often exists an initial gap or void. On the other hand, from a modeling
point of view, it is a lot easier to fill the spaces or volumes between the adjacent components with the
interface meshes, and then set an initial gap for the gasket material to account for it. As long as the
closure is less than the initial gap, no pressure is acted on the gaskets. Also, when it is under tension
loading, there will be an open gap. Therefore, gasket joints generally do not have tension pressure. A
stress cap is used to restrict tension pressure in the gasket joint elements.
The GASKET material option must be used with interface elements INTER192,INTER193,INTER194, and
INTER195.
Figure 10.2: Pressure vs. Closure Behavior of a Gasket Material (p. 321) shows the experimental pressure
vs. closure (relative displacement of top and bottom gasket surfaces) data for a graphite composite
gasket material. The sample was unloaded and reloaded 5 times along the loading path and then un-
loaded at the end of the test to determine the materials unloading stiffness.
Figure 10.2: Pressure vs. Closure Behavior of a Gasket Material
10.4.2. Input Format
You input gasket material data using TB,GASKET. The material data consists of 2 main parts: general
parameters and pressure closure behaviors. The general parameters define initial gasket gap, stable
stiffness for numerical stabilization, and stress cap for a gasket in tension. The pressure closure behavior
includes gasket compression (loading) and tension data (unloading).
The TB command specification for defining a gasket material is:
TB,GASKET,MAT,NTEMP,NPTS,TBOPT
where TBOPT = one of the following types of gasket material data:
- PARA: gasket material general parameters.
- COMP: gasket compression data.
- LUNL: gasket linear unloading data.
- NUNL: gasket nonlinear unloading data.
- TSS: gasket transverse shear stiffness data.
Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential informationMaterial Definition