p0 0.5[atm] "Pressure"
Fh p0*R*L "Hoop force"
k -1/2 "Biaxial loading parameter"
Sy_r 300[MPa] "Rivet yield stress"
fnmax Sy_r*pi*d_r^2/4 "Rivet critical normal force"
fsmax fnmax/2 "Rivet critical shear force"