Negative stiffness

In FEM, a negative stiffness represents a formulation where a force does not monotonically increase with displacement. Vertical-motion isolation is provided by a stiff spring that supports a weight loa combined with a negative – stiffness mechanism (NSM). The net vertical stiffness . This paper reports a system with . We present a new negative stiffness –based load-bearing structure with dynamically tunable stiffness.

Negative stiffness , traditionally used to . Recent research has shown that constrained bistable structures can display negative stiffness behavior and provide extremal vibrational and acoustical . By incorporating constituents of negative stiffness in structures and composites, one can attain extremely high values of mechanical damping, stiffness . A mechanical system exhibits negative stiffness when it requires a decrease in applied force to generate an increase in displacement. A California company is developing products based on a mechanism called negative stiffness to cancel vibrations. Minimization of the fundamental frequencies of a vibratory system by means of springs with “ negative ” stiffness is probably the only way to . Vibration isolation plays an important role in the operation of . Erik Runge describes how Minus K isolators are different and how they work.

When an elastic object is presse we expect it to resist by exerting a restoring force. A reversal of this force corresponds to negative stiffness. The system uses negative – stiffness mechanisms to cancel the stiffness of a spring suspension.

Reduction in stiffness magnifies the damping inherent in the . Abstract: A new kind of vibration isolator, which is base on negative – stiffness theory, is made out for nano manufacture. In this paper, vibration isolation theory is . The renormalized elastic constants can become negative at large activity, leading to the selection of spatially inhomogeneous patterns via a . Here we analyze this unconventional behavior in further detail and find theoretical, numerical and experimental evidence of negative stiffness events. Bubbles of negative stiffness material embedded in a more ordinary material may lead to composites with very high stiffness. Interfaces with negative stiffness have been considered in crystals before, but the characteristic has now also been found in modern magnetism . Yielding can be emulated in a structural system by adding an adaptive negative stiffness device (NSD) and shifting the yielding away from the main structural . Authors: Takeshi Mizuno.

While positive stiffness systems provide increasing resistance to . Although low-frequency vibration isolation can be achieved by suspending nanoinstrumentation from a ceiling or using air tables, passive . Extreme damping in composite materials with negative – stiffness inclusions. Structural weakening and addition of damping is an approach previously proposed for the reduction of seismic forces . Improving active vibration isolation by reducing suspension stiffness with a negative stiffness mechanism.

This work presents a novel class of engineered structures with significant promise to improve vibration damping treatments and isolation systems: negative. The principal resonance of a delayed piecewise-smooth (DPWS) system with negative stiffness under narrow-band random excitation is . These unique devices are able to mechanically change stiffness, either by adding positive or negative stiffness , by using different types of rotational elements. The purpose of this paper is to study the behavior of negative stiffness beams when arranged in a honeycomb configuration and to compare the energy . Elements with a negative slope in their stress-strain or force-displacement relation . Director of Thesis: Kenneth K. Seismic events have always . A new tuning mechanism based on negative stiffness rather than the traditional dynamic tuning is proposed. The experimental prove .