# OS-V: 1210 Contact with Friction

A deformable block is slid over a fixed rigid plate using enforced velocities and the problem is solved using an explicit dynamic analysis in OptiStruct. The results from OptiStruct are compared with an equivalent model in Radioss.

## Model Files

Before you begin, copy the file(s) used in this problem to your working directory.

## Benchmark Model

The finite element model consists of a deformable block on which enforced velocities are applied causing it to slide over a rigid fixed block.

Both blocks are meshed with first-order CHEXA elements and frictional contact is defined between the blocks with a friction coefficient of 0.05. The bottom block is constrained in all directions. One side of the top block is constrained along the Y direction, while the opposite side is subjected to an enforced velocity and constrained along the X, Y, and Z rotational degrees of freedom. The upper side of the top block is subjected to an enforced velocity and is constrained along the X, Y, and Z rotational degrees of freedom.

The Y and Z directional velocities are applied in the form of a sinusoidal variation as a function of time ( $t$ ) given by:(1)
$V=\frac{{V}_{m}}{2}\left[1+\mathrm{sin}\left(\frac{2\pi }{T}t+\frac{3\pi }{2}\right)\right]mm/s$
Where, ${V}_{m}$ and $T$ for Y and Z velocities are:
Direction ${V}_{m}$ $T$
Y 565 mm/s 0.009 s
Z -102 mm/s 0.001 s
The material properties are
Property
Value
Elastic modulus
193000 N/mm2
Poisson’s ratio
0.3
Density
7.75 E-09 tonn/mm3

## Results

The Y displacement results are compared between OptiStruct and Radioss at a node on the side where Y-velocity is applied. They seem to be in good agreement (Figure 3).