Property Notation Formula Single rubber layer thickness ${{t}_{r}}$ Number of rubber layers $n$ Steel shim thickness ${{t}_{s}}$ Outer diameter ${{D}_{o}}$ Inner/lead core diameter ${{D}_{i}}$ Rubber cover thickness ${{t}_{c}}$ Shear modulus $G$ Bulk modulus of rubber ${{K}_{bulk}}$ Yield stress of lead ${{\sigma }_{L}}$ Density of bearing ${{\rho }_{b}}$ Total rubber layer thickness $t_r$ $n{{t}_{r}}$ Total height $h$ $n{{t}_{r}}+(n-1){{t}_{s}}$ Bonded rubber area $A$ $\frac{\pi }{4}\left[ {{\left( {{D}_{o}}+{{t}_{c}} \right)}^{2}}-D_{i}^{2} \right]$ Lead area ${{A}_{L}}$ $\frac{\pi }{4}D_{i}^{2}$ Characteristic strength ${{Q}_{d}}$ ${{\sigma }_{L}}{{A}_{L}}$ Yield displacement $Y$ Shape factor $S$ $\frac{{{D}_{o}}-{{D}_{i}}}{4{{t}_{r}}}$ Moment of inertia $I$ $\frac{\pi }{64}\left[ {{\left( {{D}_{o}}+{{t}_{c}} \right)}^{4}}-D_{i}^{4} \right]$ Adjusted moment of inertia ${{I}_{s}}$ $I\frac{h}{{{T}_{r}}}$ Volume of bearing ${{V}_{b}}$ $Ah$ Mass of bearing ${{m}_{b}}$ ${{\rho }_{b}}{{V}_{b}}$ Diameter ratio ${{r}_{d}}$ $\frac{{{D}_{o}}}{{{D}_{i}}}$ Central hole factor $F$ $\frac{{{\left( {{r}_{d}} \right)}^{2}}+1}{{{\left( {{r}_{d}}-1 \right)}^{2}}}+\frac{1+{{r}_{d}}}{\left( 1-{{r}_{d}} \right)\ln \left( {{r}_{d}} \right)}$ Compression modulus ${{E}_{c}}$ ${{\left( \frac{1}{6G{{S}^{2}}F}+\frac{4}{3{{K}_{bulk}}} \right)}^{-1}}$ Rotational modulus ${{E}_{r}}$ $\frac{{{E}_{c}}}{3}$ Vertical stiffness ${{K}_{v}}$ $\frac{A{{E}_{c}}}{{{T}_{r}}}$ Horizontal post yield stiffness ${{K}_{d}}$ $\frac{GA}{{{T}_{r}}}$ Horizontal yield strength ${{F}_{Y}}$ ${{Q}_{d}}+{{K}_{d}}Y$ Horizontal elastic stiffness ${{K}_{el}}$ (${{K}_{1}}$) $\frac{{{F}_{Y}}}{Y}$ Stiffness ratio $\alpha$ $\frac{{{K}_{d}}}{{{K}_{el}}}$ $\left( =\frac{{{K}_{2}}}{{{K}_{1}}} \right)$ Torsional stiffness ${{K}_{t}}$ $\frac{2G{{I}_{s}}}{h}$ Rotational stiffness ${{K}_{r}}$ $\frac{{{E}_{r}}{{I}_{s}}}{h}$ Critical buckling load ${{P}_{cr}}$ $\frac{\pi \sqrt{{{E}_{r}}GI{{A}_{0}}}}{{{T}_{r}}}$ Critical buckling displacement ${{u}_{cr}}$ $\frac{{{P}_{cr}}}{{{K}_{v0}}}$ Cavitation force ${{F}_{c}}$ $3G{{A}_{0}}$ Cavitation displacement ${{u}_{c}}$ $\frac{{{F}_{c}}}{{{K}_{v0}}}$