Buckling in Deployable Booms: Folding Pattern Influence

Overview of Technical Issues:

The folding structural elements in deployable booms insufficiently resist buckling under operational compressive loads because the folding pattern introduces geometric discontinuities, stress concentrations, and residual deformations at fold lines, leading to premature structural failure during deployment or under axial loading; the goal is to understand and optimize the folding pattern influence to enhance buckling resistance and ensure reliable load-bearing performance in the deployed configuration.

Solution directions generated for this problem

Problem Direction 1 :

ImproveFold region structural strength
VS
ConstraintManufacturing precision requirement

Inspiration 1 : Cross-domain reference

Application Principle: #11 Beforehand cushioning
Cross-domain applicability Assess applicability
Force switch
Innovative Solution Refine solution

Pre-compensated fold geometry with tolerance-absorbing design margins

Design fold lines with built-in geometric compensation to absorb manufacturing variation
How to solve :
  • Implement oversized material thickness zones at fold regions — add 15–25% extra thickness within ±20mm of fold centerline to pre-compensate for geometric imperfections from ±2° angle and ±1mm radius variations
  • Incorporate pre-formed radius profiles with nominal radius 8–12mm (vs. sharp crease) directly into material forming stage — use roll-forming or composite layup with mandrel to establish fold geometry at ±0.8mm tolerance before boom assembly
  • Design gradual stiffness transition zones spanning 50–80mm on each side of fold line through tapered thickness or fiber orientation changes — creates stress redistribution buffer that maintains ≥80% nominal strength despite manufacturing deviations
Expected Effect : Fold strength recovery to 82–85% nominal; manufacturing tolerance relaxed to ±2° angle, ±1mm radius; stress concentration reduced from 2.8× to 1.7× nominal
Risk Control :
  • thickness variation control in transition zones
  • pre-formed radius consistency across production batches
  • material cost increase from thickened regions

Problem Direction 2 :

ImproveBuckling load capacity
VS
ConstraintManufacturing precision requirement

Inspiration 1 : Cross-domain reference

Application Principle: #11 Beforehand cushioning
Cross-domain applicability Assess applicability
motor
Innovative Solution Refine solution

Pre-compensated fold geometry with tolerance-absorbing transition zones

Design fold geometry with built-in tolerance compensation
How to solve :
  • Design oversized material thickness zones at fold lines (+0.3–0.5mm local thickness) that compensate for ±1–2mm positioning errors while maintaining 80% nominal strength
  • Implement gradual stiffness transition zones spanning 60–80mm on each side of fold lines with thickness tapering from 1.2× to 1.0× nominal, distributing stress and absorbing geometric variations
  • Incorporate pre-formed radius profiles (R=15–20mm) during material fabrication stage using composite layup or progressive forming, establishing fold geometry before assembly with ±0.8mm radius tolerance
Expected Effect : Strength retention ≥82%, manufacturing tolerance relaxed to ±1.5mm, stress concentration reduced to 1.6× nominal
Risk Control :
  • thickness transition zone delamination risk
  • pre-formed radius springback variation
  • local thickness increase affecting deployment kinematics

Problem Direction 3 :

ImproveStress distribution uniformity
VS
ConstraintStructural complexity

Inspiration 1 : Cross-domain reference

Application Principle: #6 Universality
Cross-domain applicability Assess applicability
Module and assembly for managing the flow of water
Innovative Solution Refine solution

Multi-functional fold line geometry with integrated load distribution channels

Fold lines serve dual structural and stress redistribution roles
How to solve :
  • Design fold lines as integrated longitudinal channels with U-shaped cross-section (depth 8–12mm, width 15–20mm) that simultaneously function as deployment hinges and stress redistribution pathways, eliminating separate reinforcement components
  • Implement gradual wall thickness transition within the channel geometry: base material thickness maintained at nominal value, channel walls taper from 1.2× to 1.0× thickness over 30mm length on each side, creating natural stress gradient without adding parts
  • Use composite laminate layup with 0°/±45° fiber orientation: 0° fibers aligned along boom axis carry axial loads, ±45° fibers concentrated in 20mm zones adjacent to fold channels redistribute shear stress, achieving material-based stress management within single-piece structure
Expected Effect : Stress concentration reduced from 2.5× to 1.4× nominal; zero additional components; buckling load recovery 30–40%
Risk Control :
  • channel dimensional tolerance ±0.3mm required
  • fiber orientation accuracy ±3° critical
  • deployment friction increase in channels

Problem Direction 4 :

ImproveFold region structural strength
VS
ConstraintMust not deteriorate

Inspiration 1 : Cross-domain reference

Application Principle: #15 Dynamics
Cross-domain applicability Assess applicability
Bladed fuse connectors for use in a vehicle battery module
Innovative Solution Refine solution

Thermally-activated stiffness transition fold hinges for deployable booms

Adaptive stiffness via thermal phase change
How to solve :
  • Embed shape memory polymer (SMP) hinges at each fold line using thermoplastic polyurethane with glass transition temperature Tg=45–55°C
  • during ground assembly and deployment at 20–30°C, SMP remains soft (flexural modulus 50–150 MPa) enabling compact folding with bending radius ≥10mm
  • upon orbital deployment, solar heating raises temperature to 60–80°C, triggering SMP transition to rigid state (flexural modulus 1200–1800 MPa), increasing fold line stiffness by 10–15× and recovering buckling load capacity to ≥80% of nominal strength
  • Integrate resistive heating elements (nichrome wire, 0.2mm diameter, 5 Ω/m) within SMP hinge layers as backup activation, consuming 2–3W per hinge for 3–5 minutes to ensure complete stiffening in shadow periods
  • Quality control protocol: verify SMP Tg within ±3°C via differential scanning calorimetry, measure deployed flexural modulus ≥1200 MPa at 70°C per ASTM D790, confirm fold line positioning tolerance ±0.8mm, conduct thermal cycling tests (−40°C to +80°C, 50 cycles) with <5% stiffness degradation acceptance criterion
Expected Effect : Buckling capacity +45–50%; fold strength 82–85% nominal; no precision manufacturing
Risk Control :
  • SMP aging under UV radiation
  • incomplete thermal activation in eclipse
  • creep under sustained compressive load
Patsnap Eureka Solution