Dry Friction Contribution to Damage‐Caused Increase of Damping in Fiber‐Reinforced Polymer‐Based Composites

Abstract

The investigations deal with the contribution of the dry friction to the damage-caused increase of the anisotropic material damping in composite materials. Plate specimens made of glass fiber reinforced epoxy were damaged in controlled impact tests using two different projectile's geometries at three different kinetic energies. Unique investigation of the damaged specimens by means of simultaneous use of a universal testing machine with X-ray computed tomography reveals slip motions between the macroscopic laminate constituents. Such motion in the damage zone unavoidably leads to an energy dissipation due to friction and hence to increase of damping. Dry friction forcesin contrast to viscous damping forcesare assumed velocity-independent in a wide range of velocities. This observation served as the basis for the formulation of a method that enables the differentiation of material-intrinsic and damage-specific energy dissipating mechanisms. The anisotropic damping properties necessary for the validation of the method were acquired using a commercially available dynamic mechanical analyzer.

Chitin nano-whiskers (CNWs) as a bio-based bio-degradable reinforcement for epoxy: evaluation of the impact of CNWs on the morphological, fracture, mechanical, dynamic mechanical, and thermal characteristics of DGEBA epoxy resin

“…However, other factors can effect this general behaviour, one being interfacial sliding whereby sliding at the interfaces between the particles and the matrix require large out of phase stress components resulting in higher loss modulus and tan delta. 47,48 Thus it is believed that the lower storage modulus and higher loss modulus & tan delta of 0.75 wt% CNWs in comparison with the other CNWs epoxy nanocomposites is a result of sliding and energy dissipation between the adjacent CNWs nano-whiskers. This also follows from the preceding discussion where the morphology of 0.75 wt% CNWs displayed the largest clustered stacks and the highest fracture toughness and resilience.…”

Comparison of the thermal, dynamic mechanical and morphological properties of PLA-Lignin & PLA-Tannin particulate green composites

“…In general, a weaker interface has increased rotational and translational degrees of freedom, which dissipates energy and reduces storage of energy across the interface. As a result, it is believed that an increase in loss modulus and damping due to weaker interfaces is by frictional dissipation mechanisms [44]. The overall mechanical behavior of the composite is the resultant of particulate reinforcement dependent primarily on particulate volume within the composite, and interface effects primarily dependent on the interfacial area and characteristics of the matrix-filler interface.5PL composites show increased storage modulus as compared to PLA however, they also display higher loss modulus compared to PLA & 10PL and higher loss tangent compared to PLA, 10PL & 15PL.…”

Explicit Finite Element Modelling as a Development Tool for New Ultrasound Testing Methodologies for Detection and Characterization of Porosity and Defects in Composites

“…In order to demonstrate the physical basis of the proposed concept, it is convenient to use a viscoelastic material model to represent the vibrational energy absorbing effects of practically occurring [19] damage-caused dry friction. Assuming the VOIGT material model, the mechanical work per cycle and per unit volume , and hence the dissipated energy of a vibrating structure is [20]:…”