RD-V: 0600 Assign Additional Non-structural Mass to a Soccer Ball

Analysis of adding additional non-structural mass to a soccer ball using /ADMAS.

The purpose of this analysis is to add non-structural mass by using /ADMAS with different inputs.

The ball (200mm diameter) is modeled with an elastic orthotropic material (/MAT/LAW19), a control volume (/MONVOL/AIRBAG1) and internal spring elements.

The analysis is done for all /ADMAS inputs.

Input Type: Description
0: Mass is added to each node of a node group.
1: Mass/N is added to each node of a node group.; N being the total number of nodes in the node group.
2: Mass/Area is the additional surface mass applied on the shell area.
3: Additional mass distributed on the part group.
4: Final mass distributed on the part group.
5: Mass is added to each single node.
6: Additional mass distributed on each single node.
7: Final mass distributed on each single node.

Options and Keywords

The following keywords are used in the models:

Materials: /MAT/LAW2 (PLAS_JOHNS) /MAT/LAW19 (FABRI) /MAT/GAS/MASS (LAWGAS) Properties: /PROP/TYPE4 (SPRING) /PROP/TYPE9 (SH_ORTH) /PROP/TYPE11 (SH_SANDW) /PROP/INJECT1 Elements: /SPRING /SHELL /SH3N	Loads: /BCS /GRAV Curves: /FUNCT Sets: /GRNOD /GRSH3N /GRSHEL /SURF /SURF/PART/EXT Solver masses: /ADMAS

Model Files

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

RD-V-0600.zip

Model Description

Units: g, ms, mm, MPa

Shell elements (/SHELL and /SH3N) were used to model the ball and a fabric elastic orthotropic material law (/MAT/FABRI) was applied. In addition, a controlled volume (/MONVOL/AIRBAG1) is created to keep the pressure inside the ball constant during the simulation. The initial ball mass is 432.55g, the target ball mass is 435g using /ADMAS.

The only load applied to the ball is gravity with /GRAV.

The ball is dropped with an initial velocity of zero.

The total mass will be estimated by HyperMesh and compared to the mass calculated by Radioss solver (in the Starter listing and in the time history).

Results

図 2. Mass calculated by HyperMesh without using /ADMAS

注: The value for the “Non Structural Mass” is zero. The total mass of the ball is 432.55g. This is calculated using material density and element volume.

/ADMAS/0:

The mass is added to each node contained in the specified node set. Each node receives 1.68e-3 g of additional mass, and the total added mass is 1.68e-3g x 1453 Nodes, or 2.445g. As expected, the total mass estimated by HyperMesh and the mass calculated by the Radioss solver (in the Starter listing and in the time history) are equal to 435g, as shown here.

表 1. Mass calculated by HyperMesh, Radioss and HyperGraph using input Type 0
HyperMesh	Radioss Starter Listing	Radioss Time History

/ADMAS/1

The added mass is divided equally among the nodes in the specified node set.

Thus, the 2.445 g mass is divided into 1453 nodes. As expected, the total mass estimated by HyperMesh and the mass calculated by the Radioss solver (in the Starter listing and in the time history) are equal to 435g, as shown here.

表 2. Mass calculated by HyperMesh, Radioss and HyperGraph using input Type 1
HyperMesh	Radioss Starter Listing	Radioss Time History

/ADMAS/2

A specified mass of 1.72e-05g is added per unit/area. As expected, the total mass estimated by HyperMesh and the mass calculated by the Radioss solver (in the Starter listing and in the time history) are equal to 435g, as shown here.

表 3. Mass calculated by HyperMesh, Radioss and HyperGraph using input Type 2
HyperMesh	Radioss Starter Listing	Radioss Time History

/ADMAS/3

A specified mass of 2.445g is added to the nodes in the specified part set. As expected, the total mass estimated by HyperMesh and the mass calculated by the Radioss solver (in Starter listing and in the time history) are equal to 435g, as shown here.

表 4. Mass calculated by HyperMesh, Radioss and HyperGraph using input Type 3
HyperMesh	Radioss Starter Listing	Radioss Time History

/ADMAS/4

The final mass of 435g is distributed to the part group. As expected, the total mass estimated by HyperMesh and the mass calculated by the Radioss solver (in the Starter listing and in the time history) are equal to 435g, as shown here.

表 5. Mass calculated by HyperMesh, Radioss and HyperGraph using input Type 4
HyperMesh	Radioss Starter Listing	Radioss Time History

/ADMAS/5

Adding the mass to each node by entering node ID and desired mass. As expected, the total mass estimated by HyperMesh and the mass calculated by Radioss solver (in the Starter listing and in the time history) are equal to 435g, as shown here.

表 6. Mass calculated by HyperMesh, Radioss and HyperGraph using input Type 5
HyperMesh	Radioss Starter Listing	Radioss Time History

/ADMAS/6 with Iflag=0: Volume weighted distribution

The desired mass to be added to each part is entered along with the part ID. As expected, the total mass estimated by HyperMesh and the mass calculated by the Radioss solver (in the Starter listing and in the time history) are equal to 435g, as shown here.

表 7. Mass calculated by HyperMesh, Radioss and HyperGraph using input Type 6 with `Iflag`=0
HyperMesh	Radioss Starter Listing	Radioss Time History

/ADMAS/6 with Iflag=1: Area weighted distribution

表 8. Mass calculated by HyperMesh, Radioss and HyperGraph using input Type 6 with `Iflag`=1
HyperMesh	Radioss Starter Listing	Radioss Time History

/ADMAS/7 with Iflag=0: Volume weighted distribution

The mass of the specified part is checked, and then the mass is added evenly to each node of the part so that the total mass of the part is equal to the specified mass.

As expected, the total mass estimated by HyperMesh and the mass calculated by the Radioss solver (in the Starter listing and in the time history) are equal to 435g, as shown here.

表 9. Mass calculated by HyperMesh, Radioss and HyperGraph using input Type 7 with `Iflag`=0
HyperMesh	Radioss Starter Listing	Radioss Time History

/ADMAS/7 with Iflag=1: Area weighted distribution

表 10. Mass calculated by HyperMesh, Radioss and HyperGraph using input Type 7 with `Iflag`=1
HyperMesh	Radioss Starter Listing	Radioss Time History

Conclusion

As shown in the study, the non-structural mass is added as defined with different inputs from /ADMAS. The target mass is found as expected. The results are consistent between HyperMesh and Radioss solver (in the Starter listing and in the time history).