The objective of this research is the computer simulation of the vibrations of the suspension system of a two-cylinder reciprocating compressor. A theoretical model is developed to describe the various steps undertaken to calculate the response of this six-degree-of-freedom rigid system. The response, which is in the form of a displacement vector, serves as the input to a computer animation of the motion of the orbit of the compressor with respect to the four suspension system springs. The theoretical model is developed by calculating (1) the System Mass and Inertial Matrix, (2) the Gyroscopic Matrix, (3) the Total Assembly Stiffness Matrix, and (4) the Shaking Forces and Moments Matrix. Experimental and finite element methods used to evaluate the parameters required to calculate these matrices are also discussed. An eigenanalysis is performed to calculate the eigenvalue frequencies and eigenvectors for the system. The force analysis is performed to calculate the forcing function in the time domain for the first 40 harmonics. The Fast Fourier Transform method is used to transform the forcing function from the time domain to the frequency domain. The validity of the results are checked by simultaneously developing another model using IMP (Integrated Mechanisms Program). The response is then calculated in original coordinates, after performing a modal transformation. Finally, the response, which is a displacement vector, is utilized by an animation program in PHIGS (Programmer's Hierarchical Interactive Graphics Standard) to animate the motion of the orbit of the compressor. / Master of Science

This thesis discusses the experimental modal analysis work done on a reciprocating Freon compressor. The primary goal of this work was to aid in the development of a dynamic finite element model for the compressor. The crankcase, the compressor shell, and the entire compressor were each studied individually so that the characteristics of each component could be determined separately. For each of the tested elements, a modal survey was done followed by the determination, with the use of a laser, of the forced frequency response shapes associated with each resonance. These shapes, along with the associated frequencies, were compared with the results from the finite element analysis model to determine if the model needed to be updated. The crankcase was also tested to determine if a rigid-body assumption would be valid for the purpose of force analysis. This study resulted in the experimental data that could be used for comparison with the finite element model results. In general, the forced frequency response shapes could be matched to the finite element mode shapes up to 1400 Hz for the empty shell and assembled compressor, 2000 for the crankcase. Also, there were several conclusions that resulted from this study. These included acceptance of the rigid-body assumption for purposes of the force analysis, the need for a further look at the dynamic variations between individual compressors, and a suggestion to move the suspension mounts to the narrow side from the broad side. / Master of Science