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A rigid/flexible multi-link mechanism simulation methodology is discussed for off-highway machinery applications. This formulation combines nonlinear large displacement dynamics with elastic structural dynamics effects. The first part of the paper briefly discusses the mathematical formulation (i.e., the 4 x 4 transformation methodology) while the second part discusses the application of the methodology. The rigid/flexible multi-link simulation methodology is used to model the dynamic response of a stiffness-sensitive loader linkage. The simulation results for the loader model are compared with the results of finite element analysis (i.e., normal mode, harmonic force and linear transient analyses).

A modal analysis methodology is presented for multi-degree-of-freedom articulated machinery and vehicles. The analytical technique formulates the eigenvalue problem for linearized, constrained dynamical systems during steady-state motion or at a static equilibrium position. The technique is implemented into a computer simulation program to compute the system modal properties. The system eigenvalues and eigenvectors are combined with the system geometrical transformation data to yield the system transfer function ratios for the generalized coordinates and points of interest, as well as the mode shapes. In turn, the frequency response magnitudes and phase angle shifts for a specified frequency range are computed from the system transfer functions.

Data envelopment analysis (DEA) is used to examine the efficiency of 74 front wheel assist agricultural tractors from three U.S. manufacturers. The outputs of drawbar horsepower and power takeoff horsepower are modeled in a constant returns-to-scale framework using three productive performance inputs (fuel consumption, slip, and center of gravity), and one price input, namely, retail tractor price. The results suggest that by and large, John Deere tractors are more DEA efficient than their competitor's tractors. However, competitor's tractors that are DEA efficient are most often the top benchmarks for DEA inefficient tractors. These results suggest that while John Deere appears to produce many quality tractors, competitor's like CNH and AGCO produce a few tractors that may be of even higher quality.

An overview of a design methodology based on finite element and fatigue analyses is described for the design of welded structures. Fatigue life is a primary design consideration for agricultural equipment structural members. The re-design of an agricultural implement frame and hitch assembly is used to illustrate the methodology for optimal design and improved fatigue life. A description of the finite element mode of the agricultural implement and the simulated loading history are described. Results from finite element analysis are used to optimize the frame member sizes and calculate the fatigue strength characteristics. This design analysis strategy provides improved fatigue life characteristics for the implement frame or welded structure.