Transient behavior of elastomeric damper and bearing materials

The transient behavior of elastomeric materials commonly used in helicopter lead-lag dampers and bearings was characterized experimentally, system types of tests performed included strain-controlled quasi-static tests, stress relaxation tests, and ramp tests with and without harmonic oscillation. For each test, time domain force and displacement data was taken and used to produce force and displacement trajectories. Generally, the quasi-static test results show that as the displacement increases, the elastomers tend to soften, except for very stiff elastomers, which tend to initially soften and then stiffen. The stress relaxation test results show that elastomers with lower loss fectors generally display lower stress relaxation levels. The ramp tests show that, for the ramp times examined in this paper, the materials exhibit little dependence on the time it takes for the displacement to change from the initial displacement to the peak displacement.