GB696881A - Improvements relating to the suspension of vibratory bodies - Google Patents

Abstract

696,881. Resilient mountings. M.B. MANUFACTURING CO., Inc. Feb. 20, 1948 [Feb. 21, 1947], No. 5144/48. Class 108 (iii). A suspension system for isolating a body against vibration with not more than two sets of coupled modes, comprises a number of vibration isolator units all having the same stiffness ratio, attached to and supporting the body at points in a plane parallel to two of the inertial axes of the suspended body, each point of attachment being determined by the formula in each of two orthogonal planes, s and d being the horizontal and vertical distances of the mounting unit axis from the c.g. (m), as shown in Fig. 11, r the radius of gyration of the body about an axis perpendicular to the plane in which s and d are measured, and Kv and Kh are the vertical and horizontal stiffnesses of the mounting. The respective curves B-H and B1-H7 (which are omitted in the upper half of the Figure for the purpose of clarity) relate to mountings having the same stiffness ratio Kv/Kh but different absolute stiffnesses, and are derived from the same equation, the left-hand side of which is multiplied by <12>#10 or a multiple thereof. The scale of the co-ordinates of the diagram is chosen so that r equals unity. The curves M represent ratios of maximum to minimum natural coupled frequencies and the curves N, ratios of minimum to translational frequency. The curves O represent the location of nodal points. In use, the outline of the body in a plane parallel with two principal axes X, Y (Fig. II), is superposed on Fig. IV with m coincident with the origin 3 and the axes X, Y parallel with the axes s/r, d/r. The points on the outline for positioning the respective mountings so that the ratio of maximum to minimum natural frequencies of the suspended body is a minimum, are indicated by the intersection of the body outline with the curves A-H and A<1>-H7. The intersection of the outline with the curves M, N, O indicate the respective frequency ratios and nodal points. Specifications 692,691 and 696,055 are referred to.