64 J.M. Liu et al. 0 0 0.25 0.5 0.75 1.0 -180 -90 0 90 180 20 40 60 80 100 Name:Ip dB Test No.:7 Input:14 Output:13 Half Spectrum SF= 10.000Hz Ave. times: 4 Df= 0.0098Hz Tot points: 401 cursor: 121 f = 1.1719Hz H = 84.050 dB((m/s2)2) Ph.= 48.682 Co.= 0.921 Fit.= 94.577% 0.50 1 1.50 2 2.50 3 3.50 (Hz) Fig. 6.4 Half spectrum of averaged four times 0 0 0.25 0.5 0.75 1.0 -180 -90 0 90 180 20 40 60 80 100 0.50 1 1.50 2 2.50 3 3.50 (Hz) Name:Ip dB Test No.:7 Input:14 Output:13 Half Spectrum SF= 10.000Hz Ave. times: 8 Df= 0.0098Hz Tot points: 401 cursor: 121 f = 1.1719Hz H = 83.999 dB((m/s2)2) Ph.= 46.913 Co.= 0.941 Fit.= 94.885% Fig. 6.5 Half spectrum of averaged eight times 6.3.2 Impact Test and Coherence Function An educational beam with both ends pinned connection, is illustrated as Fig. 6.8, to obtain the FRF between point A and point B with impact test method.
RkJQdWJsaXNoZXIy MTMzNzEzMQ==