Question

The following graph displays four different creep curves, label primary, secondary, and tertiary creep on the T2 graph. Tz > T2 >T 03>2>0 T3 or 03 Creep strain Tor 02 T, ora; T <0.41 Time A popular urban legend concerns the apparent flow of stained-glass windows in medieval cathedrals, where the glass windows are observed to be thicker at the bottom than they are at the top. Explain why (using the above creep curve) this urban legend is rubbish, justify your answer.

Answer 1

primary creep Secondary Creep 13>T,>T Tertiary 3 > 0,01 creep slop of the curve T, or 03 Creep strain or 102 Toro TK 0.47 Time

This is not true. Glass were often made by the "Crown glass" process. A lump of molten glass was rolled, blown, expanded, flattened and finally spun into a disc before being cut into panes. The sheets were thicker towards the edge of the disc and were usually installed with the heavier side at the bottom. Other techniques of forming glass panes have been used, but it is only the relatively recent float glass processes that have produced good-quality flat sheets of glass.