node mass problem

[jisb007]

Hello,

I met some weired warning message when I try to model a breakable bond:

WARNING: "In tied contact pair 3, node 291 on the slave surface UPPER_S has 9.1 times more mass than the mass of node 49901 on the master surface UPPER_M. Significant contact noise may result with the kinematic contact algorithm when the slave nodes have significantly
greater mass than the master nodes. Suggested workaround includes using mass-scaling to adjust the ratio of nodal masses."


Can someone tell me 1) why nodes have masses too? -- I thought only elements do; and 2) how can I solve it? -- My slace surface/nodes belong to a material much "lighter" than the master surface/nodes/elements.

Thanks very much.

 

[Drej]

1) Strictly speaking elements don't have mass associated with them - the corresponding nodes defining an element have the mass "smeared" at the nodes.

2) I think the answer is in your question (large differential mass). As it's only a warning, I wouldn't be concerned unless your analysis starts to fall over or your results are physically unreasonable.


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[jisb007]

Thanks. But there's the mass scaling in abaqus -- that applies to the elements, right? Also, when specifying the density of the material and to get the mass, it has to be defined on the elements as well, since only elements have "volume", not nodes. So, I am still confused why "strictly speaking", elements don't have mass and that the nodes carry them. THanks very much.