Nonlinear vibration of knitted spacer fabric under harmonic excitation

Abstract

Knitted spacer fabrics can be an alternative material to typical rubber sponges and polyurethane foams for the protection of the human body from vibration exposure, such as automotive seat cushions and anti-vibration gloves. To provide a theoretical basis for the understanding of the nonlinear vibration behavior of the mass-spacer fabric system under harmonic excitation, experimental, analytical and numerical methods are used. Different from a linear mass-spring-damper vibration model, this study builds a phenomenological model with the asymmetric elastic force and the fractional derivative damping force to describe the periodic solution of the mass-spacer fabric system under harmonic excitation. Mathematical expression of the harmonic amplitude versus frequency response curve (FRC) is obtained using the harmonic balance method (HBM) to solve the equation of motion of the system. Parameter values in the model are estimated by performing curve fit between the modeled FRC and the experimental data of acceleration transmissibility. Theoretical analysis concerning the influence of varying excitation level on the FRCs is carried out, showing that nonlinear softening resonance turns into nonlinear hardening resonance with the increase of excitation level, due to the quadratic stiffness term and the cubic stiffness term in the model, respectively. The quadratic stiffness term also results in biased vibration response and causes an even order harmonic distortion. Besides, the increase of excitation level also results in elevated peak transmissibility at resonance.

Development of data-driven modeling method for nonlinear coupling components

“…Luo et al [4] applied this method to analyze dynamic characteristics in a rubber-based rail fastener system, utilizing the superposition principle for hysteresis loop simulations on rubber components. Chen et al [5] extended this ap-preach to fabric spacers, introducing asymmetric elastic force and fractional differ-ential force. Roncen et al [6] expanded the Numerical Approach using the harmonic balance and shooting method, focusing on the softening effect in a rubber isolator subjected to random exciting forces.…”

Development of data-driven modeling method for nonlinear coupling components

“…Luo et al 4 applied this method to analyze dynamic characteristics in a rubber-based rail fastener system, utilizing the superposition principle for hysteresis loop simulations on rubber components. Chen et al 5 extended this approach to fabric spacers, introducing asymmetric elastic force and fractional differential force. Roncen et al 6 expanded the Numerical Approach using the harmonic balance and shooting method, focusing on the softening effect in a rubber isolator subjected to random exciting forces.…”

An experimental study on the vibration behavior and the physical properties of weft-knitted spacer fabrics manufactured using flat knitting technology

“…Studies have been carried out to study the vibration properties of knitted spacer fabrics from different perspectives. 34–44 Frydrysiak and Pawliczak 41 found that knitted spacer fabric has the advantage of having much lower thickness than typical sponges as vibration damping inserts in workplace seating. Krumm et al.…”

“…Chen et al. 34,44 have studied the nonlinearity in the frequency responses of weft-knitted spacer fabrics using experimental, theoretical and numerical methods.…”