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Multi-Lumen Core

The core drives the cross-section mechanics, including anisotropic bending for asymmetric profiles (a double-D bends differently across the septum than along it), and flows through every downstream tool: simulation, analysis, Reflow, and reports.

Enabling a core​

On the wizard's General Properties step, set Design mode to Multi-Lumen Core. This:

  • Adds a Core Profile step to the wizard, where the inner geometry is defined (the Step-1 diameter inputs are hidden; the core owns the inner dimension).
  • Builds the catheter inside-out: walls stack outward from the core OD, and the final OD is a computed result.

The Core Profile step​

Templates​

Pick a profile from the template gallery, then shape it with its parametric dimensions. Every dimension is unit-aware and live-previewed:

TemplateProfile
N Lumens1–8 round lumens evenly spaced on a pitch circle.
Central + N LumensA central lumen with 0–8 satellite lumens around it.
Multi-D2–4 D-shaped lumens separated by straight septa, with area-balance controls to size the lumens unequally.
Pie Sectors3–6 wedge-shaped sectors, with or without a central hub.
Round + CrescentA round lumen tangent to the outer wall, with a crescent filling the remaining bore. The crescent can be split in two.
Central + CrescentsA central lumen ringed by 2–4 crescent-shaped sections.
OvalA single horizontal oval lumen, optionally with one or two satellite lumens above/below.
Custom (Measured)Enter measured section properties (area and moments of inertia) directly when the profile comes from a supplier drawing or a measured part.

Templates with same-size lumen groups have an "All lumens are equal size" checkbox; uncheck it to dial individual lumen diameters (for example, one large aspiration lumen and smaller wire lumens on the same pitch circle).

Core material and guardrails​

  • Core outer diameter and Core material set the rod itself; the material comes from the Materials Library.
  • A status line continuously reports the minimum outer wall and minimum web (the thinnest polymer between lumens, and between lumens and the surface).
  • Geometry errors (overlapping lumens, or lumens escaping the core) block the Next button until fixed. Warnings (thin but manufacturable webs) do not block.

Core rotation​

Rotates the core about the catheter axis in 90° steps, sitting directly under the preview it re-orients. This is real assembly geometry: the rotation flows to the computed bending axes, all cross-section views, the 3D model, and the report. On a steerable design, it is how you align the core's lumens with the pullwire layout.

Per-section opt-out​

Each section has a "Use multi-lumen core in this section" checkbox (on by default). Uncheck it to build that one section on a plain bore at the core OD instead, for example a soft distal tip in front of a multi-lumen shaft.

Pullwires and the core​

Pullwires are never routed through the core. They are defined as usual on the Pullwire Settings step and run in the wall stack above the core; the wizard keeps the pullwire offset clear of the core OD automatically. To clock the core's lumens relative to the pullwires, use Core rotation on the Core Profile step.

How the core changes the analysis​

  • Anisotropic bending: asymmetric profiles report separate EIx / EIy bending stiffnesses on the Catheter Analysis tab and in the reports (plus the principal min/max range on the Review page and reports), and the dynamic simulation bends with the same independent X and Y stiffness.
  • Min. Bend Radius (first yield): the bend radius at which the core polymer first yields (onset of permanent set), the meaningful bend limit for a solid core, reported with its yield moment. Conservative: it ignores stress concentration at the lumen webs.
  • Round-bore KPIs show N/A: burst pressure and crush pressure assume a thin-walled round tube and are not reported for core sections.
  • Reflow: the core is the reflow boundary: the stackup builds outward from the core OD, and the core itself never reflows. It appears (statically) in the Reflow tab's 3D view.
  • Design Sweep: the core is treated as fixed tooling: its OD is shown read-only and cannot be swept. Sweep wall-stack parameters instead.
  • Reports: PDF and Excel document the core as authored (template, parametric dimensions, and manufacturability minima) with a cross-section image.