(Solved): A notched rectangular bar of polyacetal with dimensions given below undergoes plane-strain fractur ...

A notched rectangular bar of polyacetal with dimensions given below undergoes plane-strain fracture in three-point bending (3PB) at room temperature at an applied force \( 390 \mathrm{~N} \). Calculate \( \mathrm{K}_{\mathrm{c}} \) Find the applied force needed to fracture the same polyacetal but now in a form of a compact tension specimen. Given: For \( 3 P B \quad Y=1.09-1.73(a / W)+8.20(a / W)^{2}-14.17(a / W)^{3}+14.55(a / W)^{4} \) For CT \( Y=16.70-104.7(a / W)+369.9(a / W)^{2}-573.8(a / W)^{3}+360.5(a / W)^{4} \)