Study of Static and Dynamic Fracture Using Strain Measurements

摘要

The analysis of strain fields surrounding both stationary and propagating cracksis presented. Series expansions of the static and dynamic strain fields are developed. Gage orientation angles are then studied to optimize the strain response. The orientation angles are found to be dependent on gage type and material. Algorithms are developed which use the temporal or spatial strain variations to extract fracture parameters. The accuracy of the parameter determinations is shown to be excellent, and limits are placed on the validity of the developed methods. The methods are then applied to the analysis of a large scale crack arrest test conducted in a pressure vessel steel. The behavior of the crack-tip position with time and the propagation toughness with time, temperature and position are determined. From this information, details of the conditions at crack arrest are extracted. The propagation toughness-crack-velocity relation is then constructed.