Effect of Frequency and Position of the Accelerometer on the Displacement of Vibrating Cantilever Beam

A study of deflection on specimens has been done under forced vibratingconditions using dimensional analysis and deflection criteria to find crackposition. From various plots for cracked and un-cracked specimens, it wasfound that the locations of the cracks obtained graphically are in goodagreement with known locations of the cracks. Phase angle difference at twopoints on various specimens like cracked, un-cracked was observed torecognize the discontinuity status. Pattern of the deflection followed along thebean was used to recognize the location of the crack. Heat-treated specimenswere also used to observe the effect of molecular disturbances on the model.

Readings were observed and compared for the measurement of, deflectionof the beam at defined positions due to the different frequency on the differentspecimens. In the present investigation specimens were prepared using EN45steel and automatic muffle furnace was used for the heat treatment process.Specimens with size 500mm x 50mm x 12mm were prepared using extensiveuse of abrasive cutter. Two of the three specimens were further processedthrough heat treatment process. The heating temperature and soaking hourswere set to 930°C and half an hour respectively. Specimens were quenched tothe room temperature to obtain desired hardness and its effect on the vibrationanalysis. Hardened specimens were further clamped on the experimental setupfor useful experimentations. Experiments were conducted for the fixinglength, 400mm of specimen. Displacement for the frequency 60 Hz, 80 Hz,100 Hz and 120 Hz for various positions (i.e., 50 mm, 100 mm, 150 mm, 200mm and 250 mm from the free end) of single accelerometer was observed andplotted. The displacement value for the combinations of frequency andposition for the three specimens were compared.