Creating a mesh

Using the material properties (neglecting Poisson's ratio), we can calculate the wave speed of the material using the equations introduced earlier.

c_{d} = \sqrt{\frac{E}{ρ}} = \sqrt{\frac{207 \times 10^{9} Pa}{7800 kg / m^{3}}} = 5.15 \times 10^{3} m / s .

At this speed the wave passes to the fixed end of the bar in 1.94 × 10⁻⁴ s. Since we are interested in stress propagation along the length of the bar through time, we need a sufficiently refined mesh to capture the stress wave accurately. We will assume that the blast load will take place over the span of 10 elements. To determine the length of these 10 elements, multiply the blast duration by the wave speed:

L_{10 e l} = (3.88 \times 10^{- 5} s) c_{d} .

The length of 10 elements is 0.2 m. Since the total length of the bar is 1.0 m, we would have 50 elements along the length. To keep the mesh uniform, we will also have 10 elements in each of the transverse directions, making the mesh 50 × 10 × 10. This mesh is shown in Figure 1.

Figure 1. 50 × 10 × 10 mesh.

Seed the part with a target global element size of 0.02. Select C3D8R from the Explicit library as the element type, and mesh the part.

Note:

The proposed mesh density exceeds the model size limits of the Abaqus Student Edition. If you are using this product, specify one of the following:

A global element size of 0.04.
A 50 × 3 × 3 mesh.
A 25 × 5 × 5 mesh.