Abstract
The experimental study of heat flux evolution at the fatigue crack tip during biaxial loading was carry out in this work. The plane samples of stainless steel AISI 304 with thick of 3 mm were weakened by notch to initiate fatigue crack at the centre of samples. A contact heat flux sensor based on the Seebeck effect was used to monitor the dissipated thermal energy. During tests the samples were subjected to cyclic loading of 5 Hz with constant stress amplitude and different biaxial parameter. The experimental results confirm the previous conclusions of authors about two regime of energy dissipation at fatigue crack tip. The curve of the dissipated energy can be divided in two stages. In the second stage is characterized by classical linear relation between crack rate and energy dissipation. In the first stage the crack rate is proportional to the multiplication of the power of heat flux by crack length. The energy dissipation does not depend on the biaxial parameter during cyclic loading.
Highlights
Technical progress, complication of mechanisms and designs, ambitious projects in the field of mechanical engineering, aircraft construction, nuclear energy, and space exploration contributed to the active development of many fields of science and technology, including the fracture mechanics
It is well known that real metals have a complex structure, which is a hierarchy of different scale levels
The second stage corresponds to crack rate more 1e-6 m/cycle and it is characterised by classical linear relation between crack growth rate and energy dissipation
Summary
Complication of mechanisms and designs, ambitious projects in the field of mechanical engineering, aircraft construction, nuclear energy, and space exploration contributed to the active development of many fields of science and technology, including the fracture mechanics. A number of approaches has been developed to study the processes of nucleation and propagation of fatigue cracks [1,2,3,4]. It is well known that real metals have a complex structure, which is a hierarchy of different scale levels. The structural evolution is observed at all scale levels and leads to irreversible deformation and failure that is accompanied by energy accumulation and dissipation. The analysis of the kinetics of damage accumulation, the process of crack nucleation and kinetics of the crack development allows specialists to predict the time of structure failure and to perform in proper time a partial replacement or repair of deteriorated units of complex structures. It is very important to know the time during which the defects in the ill-behaved areas are reaching critical values
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