Strength of Glass Fibers

In Situ Visual Observation of Fracture Processes in Several High-Performance Fibers

“…3c and 4c show the failure process of S-2 Glass Ò , which upon inspection, demonstrates that the fiber undergoes a brittle fracture process that is located at a single point along the fiber gauge length. It has been previously thought that high-performance glass fibers undergo a simultaneous disintegration process, wherein numerous cracks propagate through the filament during failure [7,15]. These images clearly show that this failure process is not occurring for S-2 Glass Ò , rather the fiber is breaking in a single point, and further breakage noted in the aforementioned studies is most likely occurring during the unloading or bending of the fiber specimen post initial rupture.…”

“…For example, it has been previously alluded to that aramid fibers exhibit a possible necking behavior during failure due to post-mortem rupture morphologies showing a very fine point break [2], which as will be described, is just an alternate form of the common failure mode, namely fibrillation. Furthermore, this method also becomes inadequate when examining high-strength glass fibers, which upon tensile failure, shatter into many pieces, thereby leaving the true fracture surface unrecoverable post deformation [7,15].…”

Glass Fibre Strength—A Review with Relation to Composite Recycling

“…Around this flaw, stress will be concentrated at the crack tip, which is assumed to be infinitely sharp (although in reality, it must have atomistic dimensions). Cracks are considered the most important type of flaw, as they can only grow under the application of tensile stress [19]. However, when considering a highly brittle material, like glass, where no crack tip blunting occurs, the issue with an infinitely sharp crack tip is that any externally-applied stress immediately translates to an infinitely concentrated stress at the crack tip.…”

“…Despite the long history of GF research and development, a full fundamental understanding of the strength performance of GF still eludes us. When discussing the strength of GF, one must primarily consider the effects of flaws, and it is important to make the distinction between intrinsic and extrinsic flaws (and strengths) [19]. Extrinsic strength is controlled by the presence of flaws and their severity.…”

“…In addition to intrinsic and extrinsic strengths, the difference between GF inert and fatigue strength must also be addressed. Gupta [19] describes inert strength as that measured in the absence of fatigue, for instance by testing at very low temperature (´196˝C), where the rate of the fatigue reaction may be neglected. Conversely, fatigue strength is measured at a higher temperature (room temperature for example) and at some known level of humidity.…”