How much force can a feeding-arm tip apply to a lip before the tissue bottoms out on bone?
research/osrobot-mjlayer
With tissue as a 5 to 20 mm layer bonded to bone at 4 to 45 kPa, the force that indents it 30 % is 0.05 to 9 N, 1.3 to 1000 times below the simulated 12.6 to 53 N trial forces, so the arm needs a newton-scale force cap, not 65 N (published bottom-effect corrections, no FE run)
What it found
osrobot-mjmodulus showed the half-space Hertz model is out of range at published 4 to 45 kPa face moduli. Here the tissue is a layer of 5 to 20 mm bonded to rigid bone, using two published bottom-effect polynomials (Dimitriadis and Garcia, as tabulated by Dal Fabbro et al., ν = 0.5). The force that indents the layer by 30 % of its thickness is 0.05 to 9.4 N across tip radii 4 to 15 mm; for a 15 mm lip and the 4 mm tip it is 0.2 to 2.2 N. The simulated trial forces (12.6 to 53.3 N) exceed it by 1.3 to 1000 times, and at them the model's depth is usually beyond the layer thickness. The two corrections agree within about 40 %. Limits: homogeneous linear bonded layer, polynomial fits extrapolated from micro-scale indentation, the 30 % limit is my choice, thicknesses are lip values from one summary, no finite-element check. Not a safety case.
A figure from its own output
Paper, code and results
More in Open-source purpose-built robots
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Produced with AI assistance (Claude). Results are from the code in this repository and are simulated or stylised unless the abstract says otherwise; nothing here implies affiliation with or endorsement by any lab, researcher or company cited. MIT licensed.