Catheter shaft mechanical behavior
Predict push (Euler buckling), twist (whipping angle) and bend (cantilever deflection) for an isotropic homogeneous catheter shaft from OD, ID, length, material and temperature. Snapshot two configurations and compare them side by side.
Three independent calculations on an isotropic homogeneous shaft:
where I = π/64 · (OD⁴ − ID⁴), J = π/32 · (OD⁴ − ID⁴), A = π/4 · (OD² − ID²). Modules E, G are temperature-corrected: E(T) = E(23°C) · k(T), idem G.
Material database — 11 medical-grade polymers and 2 alloys, with temperature corrections derived from DMA measurements and literature. Pebax 35D to 72D, Nylon 12 (PA12), Pellethane TPU 75D, PEEK, PTFE, FEP, HDPE, 316L stainless, Nitinol.
For polymers, E and G drop significantly near Tg. Pebax 72D loses ~30% modulus from 23°C to 37°C; Nylon 12 and Pellethane lose ~30-35%. PEEK, PTFE, and metals are nearly insensitive in this range.
Nitinol is marked with a phase-change warning — the martensite/austenite transition near Af creates a discontinuity in mechanical behavior.
Isotropic homogeneous assumption. Real shafts are multi-layer composites with braid/coil reinforcement, multi-durometry transitions, and complex loading. These results are baseline orders of magnitude — bench testing required for final design.
Boundary condition K. The Euler factor K depends on how the shaft is constrained: 0.5 (fixed-fixed), 0.7 (fixed-pinned), 1.0 (pinned-pinned), 2.0 (cantilever). For a catheter pushed against tissue with a fixed proximal grip, K=2 is the conservative default.
Whipping convention. The torsion result expresses the angle released instantaneously when distal friction unblocks — a conservative measure of torque transmission unpredictability.
Protobrix · catheter design, prototyping & clinical small-series. ISO 13485 certified.
Want to discuss your shaft design?
Calculations assume isotropic homogeneous material. Real shafts have multi-durometry, braid reinforcement, and friction — use these results as a baseline, not as a final specification.
Stiffness gradient design, durometer transition strategy, kink-resistance trade-offs? Our catheter engineers can help with full shaft design.
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Catheter shaft mechanical behavior
Predict push (Euler buckling), twist (whipping angle) and bend (cantilever deflection) for an isotropic homogeneous catheter shaft from OD, ID, length, material and temperature. Snapshot two configurations and compare them side by side.
Three independent calculations on an isotropic homogeneous shaft:
where I = π/64 · (OD⁴ − ID⁴), J = π/32 · (OD⁴ − ID⁴), A = π/4 · (OD² − ID²). Modules E, G are temperature-corrected: E(T) = E(23°C) · k(T), idem G.
Material database — 11 medical-grade polymers and 2 alloys, with temperature corrections derived from DMA measurements and literature. Pebax 35D to 72D, Nylon 12 (PA12), Pellethane TPU 75D, PEEK, PTFE, FEP, HDPE, 316L stainless, Nitinol.
For polymers, E and G drop significantly near Tg. Pebax 72D loses ~30% modulus from 23°C to 37°C; Nylon 12 and Pellethane lose ~30-35%. PEEK, PTFE, and metals are nearly insensitive in this range.
Nitinol is marked with a phase-change warning — the martensite/austenite transition near Af creates a discontinuity in mechanical behavior.
Isotropic homogeneous assumption. Real shafts are multi-layer composites with braid/coil reinforcement, multi-durometry transitions, and complex loading. These results are baseline orders of magnitude — bench testing required for final design.
Boundary condition K. The Euler factor K depends on how the shaft is constrained: 0.5 (fixed-fixed), 0.7 (fixed-pinned), 1.0 (pinned-pinned), 2.0 (cantilever). For a catheter pushed against tissue with a fixed proximal grip, K=2 is the conservative default.
Whipping convention. The torsion result expresses the angle released instantaneously when distal friction unblocks — a conservative measure of torque transmission unpredictability.
Protobrix · catheter design, prototyping & clinical small-series. ISO 13485 certified.
Want to discuss your shaft design?
Calculations assume isotropic homogeneous material. Real shafts have multi-durometry, braid reinforcement, and friction — use these results as a baseline, not as a final specification.
Stiffness gradient design, durometer transition strategy, kink-resistance trade-offs? Our catheter engineers can help with full shaft design.
Request received.
We'll get back to you within 1 business day.
Leaving without a result? In one line — what were you looking for? It helps us improve.
Thanks for using the tool. If it saved you time:
Suggested text copied — paste it into your LinkedIn post.
Thank you.
Noted — this helps us improve.
