Sharpness of Lid Edges

Abstract

In Experiment 1, 15 plexiglass lids were constructed, using all combinations of 3 diameters (32, 70, 82.5 mm) and 5 edges (having a radius of curvature of 0, .8, 1.6, 2.4 and 3.2 mm). The lids were inserted into a torquemeter and held vs 2.3 kg-m of torque. The 44 adult subjects (18 M; 26 F) indicated their discomfort. Gender significantly affected discomfort, with female discomfort values about 70% greater than male values. For the same radius of curvature, discomfort was highest at 32 mm dia, intermediate at 82.5 mm and least at 70 mm.

In Experiment 2, 82.5 mm dia lids with edges of .8, 1.6 and 2.4 mm radii were used by 10 subjects (5 M, 5 F). The torques were 1.1, 1.7, 2.3, 2.8 and 3.4 kg-m. Female discomfort vote increased 1.9/ kg-m while male vote increased 1.2/kg-m.