Model for piano hammers: Experimental determination and digital simulation

To explain the clearly nonlinear character of the interaction between a piano hammer and the strings it hits, a model for the hammer is proposed consisting of a point mass and a nonlinear, hysteretic spring that describes the action of the felt. Experimental determinations of force are fitted with an expression of generic form F = a(δy)α, where a takes values such as 2.1, 3.5, and S. Numerical simulations of hammer and string motions based on this model are found to be in good agreement with experimental measurements.