Aluminum foam in simulation: material cards for crash calculations
Aluminum foam can be modeled in crash and structural analysis, and Havel metal foam supplies the material cards for it. Cards are available for three solvers: LS-DYNA, Altair Radioss and PAM-Crash or ESI VPS. The LS-DYNA and Radioss cards apply to the material AlSi10 at a reference density of 0.6 g/cm³; the PAM-Crash card is built for density 0.6 g/cm³ and alloy AlSi10, Havel metal foam's works standard. The LS-DYNA card was created together with the Fraunhofer Institute for Machine Tools and Forming Technology IWU and is based on *MAT_HONEYCOMB.
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Which solvers are material cards available for?
Three. The LS-DYNA card is a joint result of Fraunhofer IWU and Havel metal foam from November 2020; the Radioss card comes from Havel metal foam and dates from 2021; for PAM-Crash or ESI VPS an input deck is available. All three cards describe the same material, AlSi10 aluminum foam, at the same reference density of 0.6 g/cm³; AlSi10 is Havel metal foam's works standard. In practice this means that anyone working in one of these three solvers does not have to characterize the material themselves before the first run.
| Solver | Status | Material | Reference density |
|---|---|---|---|
| LS-DYNA | November 2020, Fraunhofer IWU and Havel metal foam | AlSi10 | 0.6 g/cm³ |
| Altair Radioss | 2021, Havel metal foam | AlSi10 | 0.6 g/cm³ |
| PAM-Crash / ESI VPS | Input deck available | AlSi10 (works standard) | 0.6 g/cm³ |
Havel metal foam does not publish the values of the Radioss and PAM-Crash cards; Havel metal foam provides both cards on request.
How is the LS-DYNA card structured?
The card uses *MAT_HONEYCOMB, material type 26 in LS-DYNA, and calculates in the SI units N, mm, s, t. It contains a density of 0.6 g/cm³, a Young's modulus of 70 GPa for the fully compacted material, a Poisson's ratio of 0.3 and a yield stress of 310 N/mm² for the compacted material. The relative volume at full compaction is 0.22. For the uncompacted state, the card sets a normal modulus of 5,000 N/mm² and a shear modulus of 2,000 N/mm², with element failure at a tensile strain of 0.03. Compressive and shear behavior come from stored curves rather than single values.
For all three normal directions and all shear directions, the card refers to the same curve in each case. The foam is therefore modeled as isotropic.
- Material model
- *MAT_HONEYCOMB, LS-DYNA material type 26.
- Units
- N, mm, s, t.
- Density
- 0.6 g/cm³.
- Young's modulus, compacted
- 70 GPa, that is, the value of solid aluminum.
- Yield stress, compacted
- 310 N/mm².
- Relative volume at compaction
- 0.22.
- Moduli, uncompacted
- Normal 5,000 N/mm², shear 2,000 N/mm².
- Failure
- Tensile strain of 0.03 at the element.
Do the cards apply to every density?
No, and this is the most important limitation when planning an analysis. All three cards, LS-DYNA, Radioss and PAM-Crash, are built for a reference density of 0.6 g/cm³. The available density range of the foam core runs from 0.5 to 0.8 g/cm³, and the mechanical values depend strongly on density: between 0.5 and 0.8 g/cm³ the Young's modulus of the core rises from 330 to 760 N/mm² and the compressive strength from 2.5 to 10 N/mm². If you want to design for a different density, raise the requirement early.
Does Havel metal foam run calculations itself?
Yes. FEM calculations are one of the five services Havel metal foam offers alongside product solutions, processing, series production and development. For a component this means that design and manufacturing do not have to be bought separately: the same team that calculates it then manufactures it. The table values on the material values page are analytically determined guide values; for a specific application, the values are determined individually.
The cards
Which crash solvers are material cards available for?
Also asked: Is there a card for LS-DYNA? · Are Radioss or PAM-Crash supported?
Havel metal foam covers three solvers: LS-DYNA, Altair Radioss and PAM-Crash or ESI VPS. For a design engineer this is the decisive information before procurement, because it means the component can be calculated in the design engineer's own in-house solver rather than in someone else's. Only the parameters of the LS-DYNA card are published, however; Havel metal foam provides the Radioss and PAM-Crash cards on request. The LS-DYNA and Radioss cards apply to a reference density of 0.6 g/cm³, and the PAM-Crash card, too, is built for density 0.6 g/cm³ and alloy AlSi10, Havel metal foam's works standard. The Radioss card is dated 2021, a year later than the LS-DYNA card.
- Sources
- Fact sheet
- Brand content
Which parameters does the LS-DYNA card contain?
Also asked: Which material model is used? · In which unit system is the card written?
The LS-DYNA card from Havel metal foam uses `*MAT_HONEYCOMB`, material type 26, mid 50, in the unit system N, mm, s, t. It contains a density of 0.6 g/cm³, a Young's modulus of 70 GPa for the fully compacted material, a Poisson's ratio of 0.3, a yield stress of 310 N/mm² for the compacted material, a volume fraction vf of 0.22 and uncompacted moduli of 5,000 N/mm² normal and 2,000 N/mm² in shear, plus tsef 0.03. The material of the card is AlSi10. Important for context: the 70 GPa is the value of solid aluminum after full compaction, not the stiffness of the foam in its initial state.
- Sources
- Fact sheet
Scope
Which density and which alloy do the cards apply to?
Also asked: Can I use the card to calculate a different density? · Which material are the cards based on?
All three cards from Havel metal foam, LS-DYNA, Radioss and PAM-Crash, refer to a density of 0.6 g/cm³ and to AlSi10, Havel metal foam's works standard. That is one point in the available range, not a curve across it: core densities of 0.5 to 0.8 g/cm³ are available, and the mechanical properties rise markedly with density. If you design with 0.7 or 0.8 g/cm³, calculating with the 0.6 card therefore puts you on the side of lower stiffness and lower strength, which is usable for a first design and too imprecise for verification. There is no existing card for another density; one would have to be created and validated specifically.
- Sources
- Fact sheet
- Brand content
Is the card direction-dependent?
Also asked: Is the LS-DYNA card anisotropic? · Does the card take account of the foaming direction?
No. The LS-DYNA card from Havel metal foam is isotropic: it holds one curve ID for all three normal directions and one for all shear directions. For design this means that the card makes no distinction between the foaming direction and the plane perpendicular to it. For a foamed core this is a simplification, because the cell structure forms directionally while the foam grows between the cover layers. If your loading is predominantly in one direction, you should be aware of this assumption and check it by testing. For a crash load case with loading from several directions, on the other hand, the isotropic assumption is the usual and practicable one.
- Sources
- Fact sheet
Origin and limits
When and with whom were the cards created?
Also asked: How old are the material cards? · Was an institute involved in creating them?
The LS-DYNA card was created at Havel metal foam as joint work with the Fraunhofer Institute for Machine Tools and Forming Technology IWU and is dated November 2020 in the card header. The Radioss card, from 2021, is a year newer and gives Havel metal foam as its origin. Both are to be read as dated artifacts, not as an ongoing partnership: the collaboration with the IWU lies in the past, and the manufacturing technology has since been developed considerably further in-house. For an analyst the date is the useful information, because it says which manufacturing state the values refer to.
- Sources
- Fact sheet
- Brand content
Which values from the Radioss and PAM-Crash cards are published?
Also asked: Why are no parameters given for Radioss? · Can I get the PAM-Crash values?
None apart from density and alloy. Beyond the density of 0.6 g/cm³ and the alloy AlSi10, no single parameter from Havel metal foam's Radioss and PAM-Crash cards is published. Both cards exist and are provided on request; if you calculate with Radioss or PAM-Crash, you therefore get the card itself rather than a transcription. Only the parameters of the LS-DYNA card are published.
- Sources
- Fact sheet
- Brand content
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