Mixed-mode dynamic stress/strain characterization of elastomeric bushing materials

The elastomeric bushings used to link military tank shoes into drive tracks that provide motive force are plagued by short lifetimes due to high stresses and extreme service conditions. The magnitude and frequency of the dynamic service stresses induce significant localized heating as a result of the hysteretic loss properties of the materials. Material development for this application has been a topic of research with limited gains in service life. The application stresses on the elastomeric components are mixed mode, including localized cyclic compression with a superimposed dynamic torsion.; This work investigates the use of a mixed mode test fixture developed to provide generalized combined loading. Dynamic mechanical properties of a range of elastomeric bushing materials are characterized under compressive loads and superimposed dynamic shear. The results suggest that a single value of elastomer dynamic loss can be used to predict the generalized hysteresis behavior, provided the conditions are scaled properly to reflect the actual stresses and strains applied in application. This behavior indicates that a single viscoelastic relaxation process remains responsible for the complex dynamic behavior observed.