Abstract
This paper presents details of a laboratory simulation of field load spectrum program developed and being implemented at the Advanced Project Engineering Division of Massey-Ferguson. The aspects of data acquisition, data reduction, and laboratory simulation are discussed.
Data acquisition includes calibration of transducers and indexing or control pulse coding of the analog tape to assist subsequent processing of data on a digital computer system. Data reduction involves analog-to-digital conversion, binary conversion, calibration, collection of useful portions of raw digitized data, transformation of data to their proper engineering units and analyses of data in time and/or frequency domains. Laboratory simulation is accomplished in two basic forms: (1) Controlled dynamometer testing, utilizing weighted composite load–frequency histograms derived from the field data, is preferred for complex mechanical systems with high inertia undergoing variety of loads with severe extremes. (2) Shaker testing, utilizing electromagnetic and electrohydraulic shakers, is preferred for structural testing of entire mechanical systems or their components by providing a duplication of field vibrations through a closed-loop magnetic tape control. Power spectral density analyses of the random signals (involving input forcing functions to the mechanical systems) are performed to correct for the frequency response characteristics of the shaker systems and the mountings used for the testing. The pertinent load spectrums can also be synthesized from their corresponding power spectra by using a white noise generator as the input device in place of the closed-loop analog tape playback system.
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