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Catheter Analysis tab

The Catheter Analysis tab is the static-design counterpart to the Simulation Analysis tab — instead of live runtime metrics, it reports the predicted static properties of each section once the model is built.

At a glance​

KPIWhat it tells youSection below
Elastic Instability RadiusTightest bend the linear-elastic model can be trusted for. Lower bound for design margins.Failure Mode Analysis
Max Moment (Instability)Bending moment at the Elastic Instability Radius.Failure Mode Analysis
Tensile Failure LoadAxial pull at which the first material reaches its tensile strength.Failure Mode Analysis
Torque FailureApplied torque at which the first material reaches its shear capacity.Failure Mode Analysis
Burst PressureInternal fluid pressure at which the wall ruptures.Failure Mode Analysis
External Crush PressureExternal pressure at which the structure collapses inward.Failure Mode Analysis
Bending Stiffness (EI)Resistance to bending. Drives trackability and tip behavior.Stiffness Properties
Torsional Stiffness (GJ)Resistance to twisting.Stiffness Properties
Axial Stiffness (EA)Resistance to stretching/compression along the axis.Stiffness Properties
Linear DensityMass per unit length.Stiffness Properties
Model Confidence chipPer-section qualitative confidence band (VHIGH / HIGH / MED / LOW) for the analytic predictions.Model confidence indicator

Units adapt to the global Metric/Imperial setting (see Menu Bar > Units). See Model accuracy and confidence for typical accuracy by regime.

Failure Mode Analysis​

  • Elastic Instability Radius: The bend radius at which the cross-section is predicted to first fail mechanically — through elastic ovalization, or through polymer matrix yielding, whichever happens at a looser bend. Below this radius, the linear-elastic model is no longer valid; the visible kink event you would observe in a physical wrap test depends on which mechanism actually governs and may occur at a different bend than predicted. Reported as a defensible lower bound for design margins, not as a prediction of the visible kink event itself. See Model Accuracy and Confidence for how this is computed for braid versus coil sections.
  • Max Moment (Instability): The internal bending moment that produces the Elastic Instability Radius, i.e., the maximum moment the linear-elastic model considers safe.
  • Tensile Failure Load: The axial pulling force at which the first material in the section is predicted to reach its tensile strength.
  • Torque Failure: The applied torque at which the first material in any layer is predicted to reach its shear capacity.
  • Burst Pressure: The maximum internal fluid pressure the section can contain before its wall ruptures.
  • External Crush Pressure: The maximum external pressure the section can withstand before its structure collapses inward. For coil-reinforced sections this is computed as the more conservative of two mechanisms (polymer-only elastic ring collapse, polymer matrix yield in hoop compression).

Stiffness Properties​

  • Bending Stiffness (EI): This value, also known as Flexural Rigidity, defines the catheter section's resistance to bending.
  • Torsional Stiffness (GJ): This value, also known as Torsional Rigidity, defines the catheter section's resistance to twisting.
  • Axial Stiffness (EA): This value represents the resistance to stretching and compression along the axis.
  • Linear Density: This is the mass per unit length of the section.

Calculated Reinforcement Characteristics​

Braid/coil characteristics are calculated for each reinforced layer for each catheter section.

  • Angle: Wrap angle of the braid/coil wire.
  • Pitch: The axial distance between successive wraps of the braid or coil wire.
  • Coverage: The percentage of the catheter's surface area covered by the reinforcing wires.
  • Fill Factor: The volume fraction of the reinforced layer occupied by braid/coil wire.
  • Total Wire Length: The total unspooled length of wire required to construct this specific layer for the current section length.

Model confidence indicator​

At the bottom of the Catheter Analysis tab, a Model Confidence card shows one chip per section, classifying how trustworthy the analytic predictions are for that section's specific design:

  • VHIGH (deep green) — The section sits in a part of VirtuCath's FEA-based validation testing where the analytic model and FEA agree very closely. Predictions should be reliable.
  • HIGH (light green) — The section is well-covered by FEA-based validation testing; the analytic result should be a reliable starting point.
  • MED (yellow) — The section sits in a region where the analytic model and FEA can disagree. Use the result for design exploration; verify with FEA before finalizing.
  • LOW (orange) — The section sits in a region where the analytic model is less reliable — typically very low or very high braid angle, very dense braids, or very soft matrices. Treat the values as approximate.

Hover any chip for a short tooltip describing what the band means against VirtuCath's FEA-based validation testing. The bands are calibrated against VirtuCath's internal FEA-based validation testing; see Model Accuracy and Confidence for what each band means quantitatively and how the bands are computed.

Model accuracy​

The stiffness values shown above (EA, EI, GJ) and several derived failure-mode KPIs (Elastic Instability Radius, Max Moment (Instability)) come from a calibrated composite-mechanics model. Accuracy is regime-dependent — typically within ~10–15% on common designs, wider on densely-packed braids at extreme angles. Errors are systematic rather than random, so relative comparisons between similar designs remain reliable even when absolute accuracy is wider.

See Model Accuracy and Confidence for the full regime guidance, including which KPIs share these accuracy characteristics, how A/B-style design comparisons stay useful in lower-accuracy regimes, and how variation in material properties versus the Materials Library defaults affects predictions.