Four types of elements are available to simulate gaskets. They are referred to as interface elements and are summarized as follows:
The 2D elements, INTER192 and INTER193, use a KEYOPT to define various stress-state options.
The following topics about the interface elements are available:
The simulation of an entire gasket joint assembly, consisting of the gasket and the structural elements on either side of the gasket, involves choosing interface elements and structural elements that have the same characteristics. Use the following table as a guideline for choosing interface and structural elements that have the same characteristics:
| For elements with these characteristics: | Use this interface element: | ... with one of these structural elements: |
|---|---|---|
| 2D, linear | INTER192 | PLANE182 |
| 2D, quadratic | INTER193 | PLANE183 |
| 3D, quadratic | INTER194 | SOLID186, SOLID187 |
| 3D, linear | INTER195 | SOLID185, SOLSH190, SOLID285 |
Proper element type is chosen based on the stress states of interest and structural element types used.
Element selection is done by the element type command, ET, for example,
ET,1,195
defines element type 1 as element INTER195.
In general, linear and quadratic elements are chosen for the following reasons:
Fewer nodes produce a smaller model that runs faster with less computer resources.
Quadratic elements are necessary if stress gradients are present in surrounding bodies.
If elements are to follow a curved boundary closely, quadratic elements are ideal because their edges are arcs.
With a free mesh (tetrahedral elements) the mid-node (quadratic) is required for an accurate solution.
When a surrounding structure can be considered as a 2D structure, for example, plane stress / strain / axisymmetric, 2D elements are the ideal choice. A good example of the use of 2D element INTER192 or INTER193 is the gasket between the "flanged" ends of pipe line. In this case the gasket properties do not vary significantly with geometric location.
For a 3D structure such as an internal combustion engine, 3D element INTER194 or INTER195 is a good choice for simulating the gasket between the cylinder head and block. In this case there is no "nice" geometry because the gasket must fill in between two complicated surfaces, in between cylinders, and around other holes and passages. Also the gasket properties can vary in different zones. For example in a cylinder head, there is usually a much stiffer zone immediately around the cylinder to contain combustion pressure (called the "fire ring"). The remainder of the gasket is much softer.