Detecting cracks in the tooth root of gears

A crack in the tooth root is the least desirable damage caused to gear units and often leads to failure of gear unit operation. A possible damage in gear units can be identified by monitoring vibrations. In relation to that, different methods of time signals analysis are presented. Signals have been obtained by experiments. Significant changes in tooth stiffness are the result of a fatigue crack in a tooth root. As a consequence, dynamic response differs from the one in concern to an undamaged tooth. Amplitudes of time signal are, by frequency analysis, presented as a function of frequencies in spectrum with time frequency analysis.     

Raman microprobe analysis of elastic strain and fracture in electrophoretically deposited CdSe nanocrystal films

The mechanical stability of nanocrystal films is critical for applications, yet largely unexplored. Raman microprobe analysis used here to probe the nanocrystal cores of thick, fractured electrophoretically deposited films of 3.2 nm diameter CdSe nanocrystals measures approximately 2.5% in-plane tensile strain in cores of unfractured films. The crack dimensions determine the overall in-plane film strain, approximately 11.7%, and the film biaxial modulus, approximately 13.8 GPa, from which the biaxial modulus of the trioctylphosphine oxide ligand matrix is inferred, approximately 5.1 GPa.