MARGINAL. Peak 41.3 MPa on the 3 mm inside fillet (face 3) at (-5.09, 5.11, 7.2). It survives the load, but the safety factor 1.14 is below the 2.5 target. Confidence is medium.

Confidence: medium. mesh convergence: von Mises stress (layer pull scaled by layer strength) still moving: 44.4 -> 41.4 -> 45.4 -> 41.3 MPa, last change 9.7% (stopped by level limit); expect about that much error; singularities: excluded from the answer: 60.4 MPa where the rigid attachment load1 grabs the part (face 13) (set by the idealized support: 56.6 -> 75.2 -> 75.1 -> 60.4 MPa); 53.1 MPa at a sharp inside corner (face 5) (a sharp corner: singular in theory, so the value depends on the mesh: 54.9 -> 52.5 -> 53.5 -> 53.1 MPa); 59.4 MPa where the rigid attachment load1 grabs the part (face 13) (set by the idealized support: 54.4 -> 55.3 -> 57.2 -> 59.4 MPa). Wobbl reports the stress 1.85 mm or more away from these spots
Max deflection 2.6 mm at (-25, 0, 55).
Material PETG (3D printed), limit 47 MPa; mass 34.95 g.
Loads: 250 N down at 0,-15,31 @ normal +y and box -21,4,10,21,6,52 rigid. Fixtures: bolt holes d=5.5.

Checks:
  [warn] mesh convergence: von Mises stress (layer pull scaled by layer strength) still moving: 44.4 -> 41.4 -> 45.4 -> 41.3 MPa, last change 9.7% (stopped by level limit); expect about that much error
  [pass] force balance: reactions balance the loads to 0.00011% (forces) and 2.7e-05% (moments)
  [skip] hand calculation: no simple beam model applies (the governing point is not between the fixtures and the load, so no single section carries it)
  [warn] singularities: excluded from the answer: 60.4 MPa where the rigid attachment load1 grabs the part (face 13) (set by the idealized support: 56.6 -> 75.2 -> 75.1 -> 60.4 MPa); 53.1 MPa at a sharp inside corner (face 5) (a sharp corner: singular in theory, so the value depends on the mesh: 54.9 -> 52.5 -> 53.5 -> 53.1 MPa); 59.4 MPa where the rigid attachment load1 grabs the part (face 13) (set by the idealized support: 54.4 -> 55.3 -> 57.2 -> 59.4 MPa). Wobbl reports the stress 1.85 mm or more away from these spots
  [pass] bolt bearing: worst hole of fix1 (d 5.5 mm) carries 81 N sideways and 52.6 N along its axis; bearing stress 2.93 MPa, safety factor 16.04 on bearing
  [pass] units and sanity: part 102 mm across, peak strain 0.02, max deflection 2.6 mm (2.5% of size): all plausible
  [pass] large deflection: deflection is large next to the wall thickness, so Wobbl solved the first mesh with large deflection theory too: the peak moves +7.1% and the deflection +6.3%; linear theory holds
  [info] load introduction: the off part loads enter through a rigid attachment (the attached part does not flex). With a distributing coupling (the attached part adds no stiffness) instead, the governing stress converges to 73.6 MPa on face 13 at (-13.8, 4.86, 15.5) (1.8x, safety factor 0.64) over 3 meshes refined around that peak: 70.7 -> 73.1 -> 73.6 MPa, last change 0.7%. The verdict is the same either way

Assumptions:
  - Linear elastic material and small deflections (no yielding redistribution, no buckling).
  - PETG (3D printed): E 2100 MPa, Poisson 0.38, von Mises vs yield 47 MPa (Prusament PETG technical data sheet).
  - Loads are static and applied all at once; no impact, vibration or fatigue.
  - Printed layers stack along z; pull across layers is judged against 70% of the in-plane strength.
  - Bolted holes are rigidly held over the hole and a washer sized ring (twice the hole radius).
  - Remote loads reach the part through a rigid attachment (the attached part does not flex).
  - Contact between separate parts, friction and preload are not modeled.

Suggested fixes:
  - Stress piles up in the sharp inside corner. A fillet of 2.71 mm (about half the 5.41 mm wall) spreads it out.
  - The wall through the peak is 5.41 mm. To reach safety factor 2.5 it needs 8.02 mm (+48%), because bending stress falls with thickness squared.
  - The peak sits where two walls meet and bend. A gusset as thick as the wall, with legs about half as long as the shorter wall, ties them together and usually cuts the corner stress by half or more.

Images: stress: images/stress.png, zoom: images/zoom.png, safety: images/safety.png, deformed: images/deformed.png, convergence: images/convergence.png
Report: report.html
