An article in the Journal of Aircraft described a new equivalent plate analysis method formulation that is capable of modeling aircraft structures such as cranked wing boxes and that produces results similar to the more computationallyintensive finite element analysis method. Natural vibration frequencies for the cranked wing box structure are calculated using both methods, and results for the first seven natural frequencies follow:
Freq. Finite Element Cycle/s Equivalent Plate, Cycle/s
1 14.58 14.76
2 48.52 49.10
3 97.22 99.99
4 113.99 117.53
5 174.73 181.22
6 212.72 220.14
7 277.38 294.80
a. Do the data suggest that the two methods provide the same meanvalue for natural vibration frequency? Use α = 0.05. Find the P-value.
b. Find a 95% confidence interval on the mean difference betweenthe two methods.