Structural Longerons
Primary Load-Bearing Longitudinal Members
Structural longerons are primary longitudinal load-bearing members that carry axial and bending loads along the length of habitat modules. Typically shaped into I-beam or C-channel cross sections, these components use aluminum-lithium alloys such as Al-Li 2195 to provide ten percent lower density and higher stiffness than conventional aluminum, connected via titanium Ti-6Al-4V splice fittings and A286 fasteners. In the lunar environment, longerons must maintain cryogenic toughness while withstanding 100 years of thermal cycling fatigue across temperature swings from -173 °C to +127 °C. Modular splice joints enable robotic inspection and replacement of damaged sections during service.
Main longitudinal structural members carrying axial loads along Ark modules
Purpose
Main longitudinal structural members carrying axial loads along Ark modules
Context
Child of L2-STR-FRAME
Principles
- ▸Longerons carry primary axial and bending loads along module length
- ▸Al-Li alloy provides 10% lower density than standard aluminum with higher stiffness
- ▸I-beam or C-channel cross sections optimized for bending stiffness vs mass
- ▸Splice joints enable modular assembly and robotic replacement of damaged sections
Typical implementations
- ▸ISS truss longeron design (Al 6061-T6)
- ▸Airbus A350 fuselage longerons (Al-Li/CFRP)
- ▸SpaceX Starship stringer-stiffened shell design
Lunar considerations
- ▸Must resist 100 years of thermal cycling fatigue (-173C to +127C)
- ▸Al-Li 2195 or 2050 alloy offers good cryogenic toughness for cold-side structures
- ▸Splice joints must be robotically inspectable and replaceable
Specifications
Functional
| primary function | Main longitudinal structural members carrying axial loads along Ark modules |
Physical
| materials | Al-Li 2195 alloy, Titanium Ti-6Al-4V splice fittings, A286 fasteners |
Interfaces
Provides
- Primary axial load carrying members
Requires
- Foundation support at longeron base
Cite this entry
Lunar Ark Codex. "Structural Longerons" (L3-STR-FRAME-LONG). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-STR-FRAME-LONG
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.