THERMAL AGING BEHAVIOR INSIDE HDR BEARING

摘要

Among various degradation factors, thermal oxidation plays the most significant role during the aging process of high damping rubber (HDR) material. However, as for HDR bearing, aging displays the feature of a diffusion-limited oxidation. Material properties develop heterogeneously from the bearing surface to the interior. In the accelerated thermal oxidation test, it is discovered that besides oxidation, temperature may also cause HDR to deteriorate. In order to distinguish the temperature effect from the oxidation effect, an accelerated aging test is designed and performed. In this test, specimens are divided into two groups. In one group, all specimens are directly exposed to air, while in the other group specimens are heated in an oxygen-off container. The oxidation group is thought to represent the HDR beating surface, while the oxygen- free group represents the interior region. In each group, there are two types of specimens, one for uniaxial tension test, and the other for lap-shear test. The environmental temperature is set as 70°C and the thermal aging time is divided into 7 stages, the initial state, 1, 2, 5, 10, 20 and 40 days. When aged to a certain time, the specimens are taken out, and the uniaxial tension test and the lap-shear test are performed. The comparison between the property variations in those two groups gives valuable insight into the thermal aging behaviors inside HDR beatings. In addition to these specimens, small sized HDR bearings are also put into the air-aging oven and accelerated aged. At the prescribed time, HDR beatings are sliced to pieces to verify the above test results.