Sigma-spring can be used as a passive
vehicle suspension system of built-in damping, a passive
vehicle suspension system with hydraulic
damper, a semi-active
vehicle suspension system of two opposite Sigma-springs (10,11) of built-in damping, or a semi-active vehicle suspension
system of two opposite Sigma-springs (10,11) penetrated at line of external loading by hydraulic
damper (12). The Sigma-spring is a spring of a special Sigma-shape above which
mass can be suspended vertically while under static or
dynamic loading conditions. The outer two arms of the Sigma-shape of the spring are inclined such that to be horizontal while fully loaded ensuring safe compression pattern. The Sigma-shape has two opposite sets of turns of different sizes one of small
radius of curvature at the side of line of the applied external load and the opposite one has large
radius of curvature in order to maximize spring
vertical deflection capability. Thickness throughout the Sigma-spring developed length is graduated in order to minimize induced stresses, weight, and cost. Stiffness of the Sigma-spring can be nonlinear in order to provide improved
vibration isolation and can be adjusted for same compact space allowance through increasing or decreasing its number of turns. The Sigma-spring can be made of
Polymeric Matrix Composite of resin strengthened at nano-scale by nanometer-sized
powder E-glass fibers. Moreover, the Sigma-spring can be made of Metallic Matrix Composite or of whole metallic monolithic material.