Vibro-insulation properties for spacer knitted fabric as a comparative study

This article presents research on spacer knitted fabrics (3D) and typical upholstery materials, as vibro-insulation inserts that can be used in workplace seating. The tests were carried out on a specially constructed laboratory stand that allowed excitation of general vibrations in the low frequency range. Each sample was placed between the sensor and the vibration actuator and vibrated in the range from 1 to 100 Hz. Seven spacer knitted fabrics with different physical and mechanical parameters and three upholstery materials were tested to check their vibro-insulation properties. The presented study showed the importance and impact of technological parameters such as thickness, areal density, stiffness, and compression module on the damping properties of spacer knitted fabrics. The research showed that all materials are characterized by vibro-insulating properties in the low frequency range. To assess the damping quality, a dimensionless SEAT (Seat Effective Amplitude Transmissibility) index was proposed, defined as the ratio of the weighted vibration acceleration determined at the station (without damping inserts) to the weighted vibration acceleration determined at the station with the use of knitted damping inserts. The work also carried out a comparative analysis of the SEAT coefficient with the physico-mechanical parameters of the studied materials, with the use of the Spearman’s rank correlation coefficient. That coefficient is used to describe the correlation of two factors characterizing the tested samples, which may influence the SEAT attenuation coefficient, e.g., surface mass on attenuation. The best and optimal vibro-insulation properties in the low frequency vibration range (f ₁ = 10 Hz and f ₂ = 40 Hz) characterized by a high protection factor (SEAT >1.5) was for the prototype of spacer knitted fabric coded W5. The thickness of W5 spacer fabric is half the size of reference foam material coded F1. The tests may have a practical application in promoting distance fabrics as a material that absorbs adverse vibrations to protect the human body.