This work explores the variation law of mechanical parameters at fatigue crack tip of compact tension specimen
with type I pre-notch based on dynamic finite element method (FEM) in the high frequency resonant fatigue crack
propagation test. The displacement fields, the strain fields and the stress intensity factors (SIF) at CT specimen fatigue
crack tip in one stress cycle and at different crack lengths under constant amplitude high frequency sinusoidal alternating
loading condition are calculated and the related variation laws of mechanical parameters are analyzed. In order to calculate
the dynamic SIF at fatigue crack tip, the static SIF has been calculated first. The compared results of the static finite
element analysis with the theoretical calculation show that finite element modeling and calculating method and respective
results are accurate. Secondly, the variation law of SIF at crack tip during the process of fatigue crack propagation test is
studied by dynamic FEM. Finally, the high frequency resonant fatigue crack propagation test has been performed and the
dynamic strain gauge is used to measure the strain at crack tip during one stress cycle. The research results show that during
crack stable propagation stage, the displacement, strain and SIF at type I fatigue crack tip are in the same form having
high frequency resonant load, and the displacement, strain and SIF amplitude increase with the crack growth. The error of
static SIF between the calculated result by FEM and the theoretical result is 2.51%. The maximum error of the strain at
crack tip between the FEM calculating result and the experimental result is 2.93%.