Column dampers with negative stiffness: high damping at small amplitude

High structural damping combined with high initial stiffness is achieved at small amplitude via negative stiffness elements. These elements consist of columns in the vicinity of the post-buckling transition between contact of flat surfaces and edges of the ends for which negative incremental structural stiffness occurs. The column configuration provides a high initial structural stiffness equal to the intrinsic stiffness of the column material. Columns of the polymers polymethyl methacrylate (PMMA) and polycarbonate were used. By tuning the pre-strain, a very high mechanical damping was achieved for small amplitude oscillations. The product of effective stiffness and effective damping as a figure of merit vertical bar E-eff vertical bar tan delta(eff) of about 1.5 GPa was achieved for polymer column dampers in the linear domain and about 1.62 GPa in the small amplitude nonlinear domain. For most materials this value generally never exceeds 0.6 GPa.