Controllable bending stiffness and damping has significant applications in soft robotics, especially for soft slender manipulator arms inspired by octopus tentacles. The bending moment on a solid slender beam is balanced by the sum of moments generated by internal stresses. Resulting stresses are not controllable and decided by the bending curvature, area moment of inertia and elastic modulus o...

A major challenge in robotics and computational neuroscience is relative to the posture/movement problem in presence of kinematic redundancy. We recently addressed this issue using a principled approach which, in conjunction with nonlinear inverse optimization, allowed capturing postural strategies such as Donders' law. In this work, after presenting this general model specifying it as an exten...

The distribution of elastic stiffness and damping of individual phases in an α + β titanium alloy (Ti-6Al-4V) measured by using atomic force acoustic microscopy (AFAM) is reported in the present study. The real and imaginary parts of the contact stiffness k (*) are obtained from the contact-resonance spectra and by using these two quantities, the maps of local elastic stiffness and the damping ...

A theoretical framework is presented for the estimation of the physical parameters of a structure (i.e., mass, stiffness, and damping) from measured experimental data (i.e., input–output or output-only data). The framework considers two state-space models: a physics-based model derived from first principles (i.e., white-box model) and a data-driven mathematical model derived by subspace system ...

Gas foil bearings (GFBs) are finding widespread usage in oil-free turbo expanders, APUs and micro gas turbines for distributed power due to their low drag friction and ability to tolerate high level vibrations, including transient rubs and severe misalignment, static and dynamic. The static load capacity and dynamic forced performance of GFBs depends largely on the material properties of the su...

Aeroelastic two-dimensional wing section with both trailing-edge (TE) and leading-edge (LE) was investigated in this paper through numerical simulation in time domain. Structural stiffness and damping in pitch degree of freedom were represented by nonlinear polynomials. Open-loop limit cycle oscillation (LCO) characters of two examples were studied, and flutter boundaries with initial condition...

Dynamic properties of the soils at the Lotung test site, Lotung, Taiwan, are estimated from seismic vertical array measurements (input± output data sets) using both time-invariant and time-variant parametric modeling methods (system identi®cation). Soil properties are directly mapped from model parameters to an equivalent lumped mass model of the soil interval. Shear stiffness and damping ratio...

A technique to identifY damping parameters directly from the frequency response functions (FRF) in matrix forms has been developed. Furtl1ermore, the technique identifies the viscous damping and structural damping coefficients separately. The technique provides more accurate damping values because it does not rely on the information of the natural modes as in the conventional method. The dampin...