Abstract
There are two kinds of rubber vibration isolators such as bonded and unbonded among the compression type. We compared these two types in vibration tests, in which correction of shape effect was made by applying Hattori-Takei's formula. In addition to this the authors checked the accuracy of successive approximation method by this formula. In this calculation one constant called shape factor... (cross sectional area)/(free surface area) was taken. When rubber is deformed the cross sectional area and free surface can roughly be obtained. If the rubber is compressed between lubricated metals the cross section varies uniformly along to its axis, enabling the calculation of true section and surface. In order to compare the characteristics, we took three cases as follows:
(A) Bonded type.
(B) The contents and dimensions of rubber are the same to (A). The used unbonded specimens are held between two metal parts polished by No. 0 sand paper.
(C) The specimen is the same to (B), prouided it is lubricated with silicone in the contact faces between rubber and metals.
Using these types of isolators, we obtained many data in various mean stresses from experiments, and calculated characteristics in other mean stress from zero stress, and came to the following conclusions.
(1) The stiffness by the statical tests, (A) is the largest and (C) is the smallest.
(2) In (A) its complex modulus and loss factor are the largest, and in (C) they are the smallest.
(3) The amplitude dependencies are similar in these three cases.
(4) Calculated values by the successive approximation method are larger than (A) and smaller than (B), and (C) is quite another.
(5) Hattori-Takei's formula is applicable so long as statical deflection by mean stress is not too large.
(6) The differences between (A) and (B) are taken as chiefly due to the penetration of metal into rubber and sliding deformation of rubber on contact faces with metals as well.
