Equivalence of light-control-point instabilities and spurious low-frequency modes

Establish whether light-control-point instabilities and trimming-induced spurious low-frequency modes are equivalent phenomena in row-sum-lumped trimmed isogeometric discretizations.

Background

The paper discusses two related phenomena associated with strongly reduced active supports and small lumped masses. Light control points are stabilized relative to neighboring control points, whereas trimming-induced spurious low-frequency modes arise from spectral effects associated with reduced support and mass lumping.

Although the phenomena appear related, the authors state that their equivalence has not been established. Resolving this relationship could clarify whether light-control-point stabilization addresses the same instability mechanism as the observed low-frequency spectral pathologies.

References

Although light-control-point instabilities and trimming-induced spurious low-frequency modes are both associated with strongly reduced active supports and small lumped masses, an equivalence between the two phenomena has not been established.

— Boundary-Level-Constrained Refinement for Suppressing Trimming-Induced High-Frequency Outliers in Explicit Isogeometric Analysis  (2609.10161 - Hollweck et al., 9 Sep 2026) in Section 4, subsection “Applicability and limitations,” paragraph on light control points