The Truss, Explicit Dynamics (truss) interface (), found under the Structural Mechanics branch () when adding a physics interface, is used for general time explicit analysis of slender elements that can only sustain axial forces. It can be used for analyzing truss works where the edges are straight, or to model sagging cables like the deformation of a wire exposed to gravity. It is available in 3D and 2D.

This interface is similar to the The Truss Interface, upon which it is based. There are a number of specializations for explicit dynamics, but the interface can also be used with most other study types. The most important use case for that is to provide initial conditions for a time-explicit analysis.

The default material model is Linear Elastic Material. With the Nonlinear Structural Materials Module, you can also model Plasticity.

When this physics interface is added, these default nodes are also added to the Model Builder: Linear Elastic Material, Cross-Section Data, Free (a condition where points are free, with no loads or constraints), and Initial Values. Then, from the Physics toolbar, you can add other nodes that implement, for example, loads and constraints. You can also right-click Truss, Explicit Dynamics to select physics features from the context menu.

The Label is the default physics interface name.

The Name is used primarily as a scope prefix for variables defined by the physics interface. Refer to such physics interface variables in expressions using the pattern <name>.<variable_name>. In order to distinguish between variables belonging to different physics interfaces, the name string must be unique. Only letters, numbers, and underscores (_) are permitted in the Name field. The first character must be a letter.

The default Name (for the first physics interface in the model) is truss.

From the Structural transient behavior list, select Include inertial terms (the default) or Quasistatic. Use Quasistatic to treat the dynamic behavior as quasi static (with no mass effects; that is, no second-order time derivatives). Selecting this option gives a more efficient solution for problems where the variation in time is slow when compared to the natural frequencies of the system. The default solver for the time stepping is changed from Generalized alpha to BDF when Quasistatic is selected.

From the Store dissipation list, select Individual contributions, Total, or Off.

Select Individual contributions to treat each dissipative process independently. Selecting this option gives a more flexible implementation for problems where dissipation occurs at different time scales, and you want to distinguish each phenomenon separately.

Select Total to accumulate all the dissipative processes into one variable.

The dependent variable (field variable) is for the Displacement field u which has two components (u, v) in 2D and three components (u, v, and w) in 3D. The name can be changed but the names of fields and dependent variables must be unique within a model.