Fracture behaviour of notched round bars made of PMMA subjected to torsion at −60 °C

This paper presents seventy new experimental results from PMMA notched specimens tested under torsion at −60 °C. The notch root radius ranges from 0.025 to 7.0 mm. At this temperature the non-linear effects previously observed on specimens of the same material tested at room temperature strongly reduce.The averaged value of the strain energy density over a control volume is used to assess the critical loads to failure. The radius of the control volume and the critical strain energy density are evaluated a priori by using in combination the mode III critical stress intensity factor from cracked-like specimens and the critical stress to failure detected from semicircular notches with a large notch root radius.

► Seventy new tests on notched specimens made of polymethyl-methacrylate are summarised. ► The tests are carried out at low temperature (−60 °C) under torsion loading. ► In all cases static failure is more brittle than previous tests at room temperature. ► Such results can help in evaluating theoretical models of the fracture under mode III loading. ► A final synthesis based on the strain energy density is carried out.