Explicit dynamics: Taylor bar impact, convergence in the time step
Explicit dynamics (impact)PASS · 0.04%A steel bar hits a rigid wall at 150 m/s (the velocity is given to ALL nodes of the body, interior ones included). The mean plastic strain is computed at four time-step factors; the change between successive factors must shrink and the last one must stay within 2 %. The earlier built-in explicit law grew the plastic strain 6-fold when the step was cut 16-fold, because it accumulated plastic strain once per step on a held strain. This is a convergence study, not a comparison with an experiment.A steel bar hits a rigid wall at 150 m/s (the velocity is given to ALL nodes of the body, interior ones included). The mean plastic strain is computed at four time-step factors; the change between successive factors must shrink and the last one must stay withi… show full text
- Tolerance:
- 5%
Problem statement
- Geometry
- Bar 25.4 × 6.4 × 6.4 mm, tetrahedral mesh (Netgen, element size 1.6 mm).
- Material
- Steel: E = 200 GPa, ν = 0.3, ρ = 7850 kg/m³; J2, yield 400 MPa, linear hardening, tangent modulus 2 GPa.
- Boundary conditions
- Initial velocity 150 m/s along -x for the whole body; rigid wall at x = 0 (penalty contact, no friction); bulk viscosity 0.5 / 0.05; end time 40 µs; time-step factor 0.4, 0.2, 0.1, 0.05.
- Measured quantity
- Mean plastic strain at the end for each factor; the change 0.1 vs 0.05 (must be below 2 %) and the monotone decrease of the change.
WebCAE Terminal
Paste these commands into the Terminal panel inside WebCAE. They use the same text DSL as the application; run one command per line:
units mm
material E=2e11 nu=0.3 density=7850 plasticity=j2 yield=400e6 hardening=linear et=2e9
box dx=25.4 dy=6.4 dz=6.4
mesh tet size=1.6
bc explicit_velocity body vx=-150
bc rigid_wall plane x 0 friction=0
explicit endTime=0.00004 dtScale=0.4 saveStride=1000000 bulkQ1=0.5 bulkQ2=0.05
solve explicit
probe explicit_plastic_strain id="ep0.4"
probe explicit_displacement_x agg=min id="umin0.4"
probe explicit_energy kind=kinetic id="ke0.4"
probe explicit_energy kind=total id="et0.4"
probe explicit_steps id="n0.4"
explicit endTime=0.00004 dtScale=0.2 saveStride=1000000 bulkQ1=0.5 bulkQ2=0.05
solve explicit
probe explicit_plastic_strain id="ep0.2"
probe explicit_displacement_x agg=min id="umin0.2"
probe explicit_energy kind=kinetic id="ke0.2"
probe explicit_energy kind=total id="et0.2"
probe explicit_steps id="n0.2"
explicit endTime=0.00004 dtScale=0.1 saveStride=1000000 bulkQ1=0.5 bulkQ2=0.05
solve explicit
probe explicit_plastic_strain id="ep0.1"
probe explicit_displacement_x agg=min id="umin0.1"
probe explicit_energy kind=kinetic id="ke0.1"
probe explicit_energy kind=total id="et0.1"
probe explicit_steps id="n0.1"
explicit endTime=0.00004 dtScale=0.05 saveStride=1000000 bulkQ1=0.5 bulkQ2=0.05
solve explicit
probe explicit_plastic_strain id="ep0.05"
probe explicit_displacement_x agg=min id="umin0.05"
probe explicit_energy kind=kinetic id="ke0.05"
probe explicit_energy kind=total id="et0.05"
probe explicit_steps id="n0.05"Results comparison
| Reference value | <εp> converges with Δt: last step change < 2 % (0.1 → 0.05) |
| Our result | <εp> = 0.140210.139830.139620.13956 at dtScale 0.40.20.10.05 |
| Deviation | 0.04% |
| Tolerance | 5% |
| Status | PASS · 0.04% |
| Element family | Solid element |
| Mesh details | tet 1978 elements, 531 nodes (Netgen, native), four explicit;: webcae_solve (native) |
Updated: 2026-10-21 · WebCAE solver