Dynamic analysis of structures with elastomers using substructuring with non-matched interfaces and improved modeling of elastomer properties

A variety of engineering structures are composed of linear structural components connected by elastomers. The components are commonly analyzed using large-scale finite element models. Examples include engine crankshafts with torsional dampers, engine structures with an elastomeric gasket between the head and the block, engine-vehicle structures using elastomeric engine mounts, etc. An analytical method is presented in this research for the dynamic analysis of large-scale structures with elastomers. The dissertation has two major parts. In the first part, a computationally efficient substructuring method is developed for substructures with non-matched interface meshes. The method is based on the conventional fixed-interface, Craig-Bampton component mode synthesis (CMS) method. However, its computational efficiency is greatly enhanced with the introduction of interface modes. Kriging interpolation at the interfaces between substructures ensures compatibility of deformation.;In the second part, a series of dynamic measurements of mechanical properties of elastomers is presented. Dynamic stiffness as a function of frequency under controlled temperature and vibrational amplitude is measured. Also, the strain and stress relaxation behavior is tested to investigate the linearity and histeresis of an elastomer. The linearity of dynamic stiffness is studied and discussed in detail through the strain and stress relaxation test. The dynamic stiffness of elastomers is measured at different conditions such as temperature, frequency, and amplitude. The relationships between dynamic stiffness and temperature, and frequency and amplitude are discussed.;After the dynamic properties of an elastomer are measured, a mathematical model is presented for characterizing the frequency and temperature-dependent properties of elastomers from the fundamental features of the molecular chains forming them. Experimental observations are used in the model development to greatly enhance the current analytical capabilities of elastomer modeling, especially in the noise and vibration control area. A frequency-domain vibration analysis of an engine-vehicle system is performed to demonstrate the advantages of the developed mathematical modeling of elastomers.