Experimental requirements of small and large scale dynamic fracture mechanics testing
The paper deals with experimental requirements of dynamic fracture mechanics tests in general with special focus on ductile cast iron materials. This is based on instructions for dynamic measurement techniques provided by the standards ASTM E 1820 and BS 7448-3 which were compared and rated. The low blow multiple specimen technique using a drop tower was investigated for crack resistance curve determination on SE(B)25x25 specimens. It was shown that no detrimental effects should be expected from the second impact of the rebounded striker. Strain gage instrumentations for direct force measurement according to the standards provided different results. The ASTM position should be preferred. Important conclusions were drawn concerning hidden friction in drop towers from a comparison of electro-optically measured displacement and calculations from force-time record. Full blow large scale tests on SE(B)140x280 specimens were performed using a servo-hydraulic test system to determine dynamic fracture toughness values. Different strain gage instrumentations were compared with respect to their force measurement capability. For displacement measurement only a non-contact electrooptical camera technique was applicable. An appropriate method of instrumentation was identified whose results show good agreement with numerical simulations of the tests. It can be concluded that the recommendations of the test standards provide different results. Therefore, they must not simply be transferred to the own specific test requirements. It is regarded absolutely essential for dynamic fracture mechanics tests in general that all measuring techniques are being validated in advance.
dynamic fracture mechanics testing ductile cast iron measurement
Wolfram Baer
BAM Federal Institute for Materials Research and Testing,Berlin,Germany
国际会议
北京
英文
1-10
2013-06-16（万方平台首次上网日期，不代表论文的发表时间）