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The dynamic analysis of a swather/windrower header first included an initial analytical model that predicted natural frequencies (7.6, 8.9, 10.6, and 12.5 Hz) and associated mode shapes of the header. The mode shapes indicated that the header oscillated predominantly in the vertical direction and the excitation force during the experimental modal test should be applied in the vertical direction near the centre rear of the header. An experimental modal test was then completed to determine the natural frequencies, mode shapes, and damping coefficients of the header. While the header was supported in its working environment, four natural frequencies within the 7.5 to 14.0 Hz range (7.7, 9.4, 10.5, and 12.5 Hz) and the associated mode shapes were determined. The damping coefficients were 0.039, 0.020, 0.026, and 0.013, respectively. Inadequacies of the initial analytical model were identified by comparing the predicted results with experimental values and steps were taken to reduce modelling errors. The modified analytical model predicted natural frequencies that were similar to the results from the initial analytical model, but the adjusted mode shapes more closely simulated results from the experimental work.
T.G. Crowe and G.E. Laliberte 1996. DYNAMIC ANALYSIS OF A SWATHER!WINDROWER HEADER. Canadian Agricultural Engineering 38(1):13-20.
Canadian Society for Bioengineering