RD-E: 1703 Distorted

Units: mm, ms, g, N, MPa

The material used follows an isotropic elasto-plastic (/MAT/LAW2) with the Johnson-Cook plasticity model, with the following characteristics:

Material Properties

Initial density

7.8 x 10^-3 $$\left[\frac{g}{m{m}^3}\right]$$

Young's modulus

210000 $\left[\mathrm{MPa}\right]$

Poisson ratio

0.3

Yield stress

206 $\left[\mathrm{MPa}\right]$

Hardening parameter

450 $\left[\mathrm{MPa}\right]$

Hardening exponent

0.5

Maximum stress

340 $\left[\mathrm{MPa}\right]$

Figure 2. Problem Studied

Model Method

Four beams are modeled with different kinds of mesh, all having 56 elements in length and 8 in height. The layout of the elements is shown in Figure 3.

The following are tested for each model:

• Element formulation:
  • BT_TYPE1
  • BT_TYPE3
  • QEPH
  • BATOZ
  • C0
  • DKT18
• Plasticity:
  • Global plasticity
  • Progressive plasticity with five integration points
  • Iterative plasticity with five integration points and variable thickness

Figure 3. Meshes

Mesh Influence of a Given Shell Using Global Plasticity and BT_TYPE3 Formulation

Figure 4. Total Energy for a BT_TYPE3 Formulation

Figure 5. Hourglass Energy for a BT_TYPE3 Formulation

Figure 6. Force for a BT_TYPE3 Formulation

Influence of Element Formulation Using Mesh 1 and Global Plasticity

Figure 7. Total Energy for Different Element Formulation

Figure 8. Total Energy for Different Element Formulation

Figure 9. Hourglass Energy for Different BT Element Formulation

Figure 10. Force for Different Element Formulation

Figure 11. Force for Different Element Formulation

Influence of Plasticity Options Using Mesh 0 and BT_TYPE3 Formulation

Figure 12. Total Energy

Figure 13. Hourglass Energy

Figure 14. Crushing Force

Figure 15. MESH 0

Figure 16. MESH 1

Figure 17. MESH 2

Figure 18. MESH 3

Figure 19. Formulation: BT_TYPE1

Figure 20. Formulation: BT_TYPE3

Figure 21. Formulation: BT_TYPE4

Figure 22. Formulation: QEPH

Figure 23. Formulation: BATOZ

Figure 24. Formulation: DKT18

Figure 25. Formulation: C0

Conclusion

The crash of a box beam using several meshes and finite element formulations was studied in detail. The simulation results for uniform, mapped and transit meshes are classified and compared for each different shell formulation. The results obtained illustrate the sensitivity of the shell elements with respect to the quality of the mesh for a typical crash problem.