Thermal Isolation Bracket — Design Study

Three bracket geometries were developed in Siemens NX to reduce conductive heat leakage prior to Simcenter thermal simulation.

Model

Heat conduction through the bracket is governed by Fourier's Law: q = (k · A / L) · ΔT.

Geometric Levers:
• A_eff: Effective cross-section of remaining ligaments.
• L_eff: Effective conduction path length (serpentine route).

Thermal resistance Rth ≈ Leff / (k · Aeff). By maximizing Leff and minimizing Aeff, the geometry creates a conductive bottleneck.

Setup

Base plate: 100 × 80 mm
Thickness: 8 mm
Material: Al 6061
Fasteners: Ø6.6 through, counterbore 11 mm

k and ΔT held constant → ranking follows A_eff / L_eff
Design 1 — Baseline (2 slots)

Straight slots reduce the conduction cross-section. Heat still has a relatively direct route across the remaining bridges.

Design 1 front view
Front view
Design 1 isometric view
Isometric view
  • Change: Aeff decreases.
  • Expectation: moderate increase in Rth.
  • Tradeoff: simplest machining; baseline case.
Design 2 — Center slit with radiused ends

The center slit further restricts conduction through the middle while keeping symmetry. Radiused ends are included for stress relief.

Design 2 front view
Front view
Design 2 isometric view
Isometric view
  • Change: smaller Aeff through the main heat bridge.
  • Intent: radii reduce stress concentration at slot ends.
  • Expectation: higher Rth than Design 1.
Design 3 — Serpentine multi-pass slot

The serpentine forces a longer conduction route through remaining ligaments, increasing Leff and reducing Aeff.

Design 3 front view
Front view
Design 3 isometric view
Isometric view
  • Change: Leff increases; Aeff decreases.
  • Expectation: highest Rth (lowest conductive heat leak).
  • Tradeoffs: more machining, lower stiffness, and higher ligament stress → verify.

Best expected isolation of the three designs (screening-level model).

Engineering Detail: 1.5mm Thermal Relief Pocket

A 1.5mm recessed pocket was integrated into the serpentine path to further decouple the heat source from the mounting interface.

  • Thermal Objective: Minimizing the conduction cross-section to create a high-resistance bottleneck for heat flux.
  • Mechanical Constraint: 1.5mm depth optimized to balance thermal path restriction with structural requirements for bolt pre-load and assembly torque.
  • Validation Goal: Analyze von Mises stress at pocket-to-ligament transitions in Simcenter 3D to ensure safety factors are maintained under thermal expansion loads.
Design ranking

With the same k and ΔT across all cases, heat leak scales with Aeff/Leff. Expected ranking: Design 3, then Design 2, then Design 1. Final selection should be confirmed with thermal FEA and a stress check at slot ends/ligaments.

Design Geometry change Thermal lever Tradeoff
1 Two straight slots Aeff ↓ Simple manufacturing
2 Center slit + radiused ends Aeff ↓↓ Lower stiffness than 1
3 Serpentine multi-pass Leff ↑↑ and Aeff ↓ Machining + ligament stress/fatigue checks
Design 1
Baseline
Geometry
Two straight slots
Thermal
Aeff ↓
Tradeoff
Simple manufacturing
Design 2
Center slit
Geometry
Center slit + radiused ends
Thermal
Aeff ↓↓
Tradeoff
Lower stiffness than 1
Design 3
Lowest heat leak expected
Geometry
Serpentine multi-pass
Thermal
Leff ↑↑ and Aeff ↓
Tradeoff
Machining + ligament checks
Simcenter 3D thermal simulations
Coming soon

Thermal isolation bracket simulation

NX geometry → Simcenter temperature and heat flux simulation