| บทคัดย่อ(English) |
The accuracy of the vibration measurement of rectangular thin plates was studied using scalinglaw for vibration problem. A scaling law for vibration response of rectangular isotropic plateswas derived from the governing equation and verified with closed form solutions. The experimentstudy was conducted on two groups of the specimens; a group of the same material and a groupwith different material. Rectangular plates with SSSS, SFSS, SFSF, and SSFF boundary conditionswere identified as a model or a prototype and tested for natural frequencies using impact testmethod. Natural frequencies from the first three modes were obtained from the vibrationresponse in frequency domain. Measured natural frequency of a model was substituted into thescaling law to determine the scaling natural frequency of the corresponding prototype which wasthen compared to the measured natural frequency to determine the accuracy of the vibrationmeasurement. Natural frequencies of the prototype determined from both approaches agree witheach other very well. From the comparisons, the average and the standard deviation of percentdiscrepancy between measured and scaling natural frequencies of the prototype is 0.24(+,ฑ)6.51%. The accuracy in this study is notably better that of the previous study on scaling lawfor buckling of plate. The use of scaling law to determine the accuracy of the vibrationmeasurement is better than that of comparing the measured natural frequency with the closedform solution since it is impossible to build the ideal simple support or clamped supportboundary conditions in the experiment. With a scaling law, the ideal boundary condition is notrequired in the experiment setup. |
