No abstract

The presented work is devoted to the experimental study of heat dissipation process caused by fatigue crack propagation. To investigate a spatial and time temperature evolution at the crack tip, set of experiments has been carried out using plate titanium specimens with pre-grown centred fatigue crack. An original mathematical algorithm for experimental data treatment has been developed to obtain the power of heat dissipation caused by plastic deformation at the crack tip. The algorithm includes spatial-time filtration and relative motion compensation procedures. The time dependence of the stored energy was calculated as the difference between work caused by plastic deformation near the crack tip and heat dissipation energy obtained from experimental data. As a result, it has been shown that the stored energy has to accumulated during the fatigue test and has to be equal to zero when the crack reaches the critical length corresponding to the failure of sample.

No abstract

No abstract

No abstract

No abstract

No abstract

In this paper the so-called Theory of Critical Distances is reformulated to make it suitable for estimating the strength of notched metals subjected to dynamic loading. The TCD takes as its starting point the assumption that engineering materials' strength can accurately be predicted by directly post-processing the entire linear-elastic stress field acting on the material in the vicinity of the stress concentrator being assessed. In order to extend the used of the TCD to situations involving dynamic loading, the hypothesis is formed that the required critical distance (which is treated as a material property) varies as the loading rate increases. The accuracy and reliability of this novel reformulation of the TCD was checked against a number of experimental results generated by testing notched cylindrical bars of Al6063-T5. This validation exercise allowed us to prove that the TCD (applied in the form of the Point, Line, and Area Method) is capable of estimates falling within an error interval of ±20%. This result is very promising especially in light of the fact that such a design method can be used in situations of practical interest without the need for explicitly modelling the non-linear stress vs. strain dynamic behaviour of metals.