APPARATUS FOR PREVIOUSLY INTRODUCING FATIGUE CRACK TO COD TEST PIECE FOR FATIGUE TESTER

摘要

PURPOSE:To make it possible to introduce precracks to two test pieces simultaneously and improve efficiency of COD testing operation by mounting a transverse rod and two test pieces horizontally and perpendicularly to each other between the upper load head and the lower horizontal table. CONSTITUTION:When a load head (b) is lowered by the descent of an elevating head, the pressing down force of the load head (b) is divided into two by a transverse rod (c), and two test pieces (d) are pressed down by second load rollers 3 and 3' of the transverse rod (c). The position where the second load rollers 3 and 3' press down the test pieces (d) is located in the exact middle of the interval (m) between supporting rollers 1 and 1' on blocks 2 and 2'. Therefore, the precrack introducing operation is performed on the two test pieces (d) under equal pressures and equal supporting conditions. When the precracks reach a crack gauge (f) a signal is outputted to stop the pressing down.