Relationship between mirror dimensions and failure stress for optical fibers
Standard glass optical fiber was intentionally damaged and strength tested in tension for a wide range of failure stress values. The mirror/mist boundary on each specimen was measured and compared to the measured failure stress. When the size of the fracture mirror is small compared to the fiber diameter, the well-known linear square root dependence of strength on mirror size was reaffirmed. However, when the mirror size approaches the fiber diameter, this relationship does not hold. The classical relationship overestimates the failure stress for large mirrors. It was determined that the circular shape of the fiber contributes to, but can not fully account for, departure from the classical strength/mirror relationship. A new empirical relationship was developed to enable predictive determinations of failure stress to levels as low as 20 to 25 kpsi (0.14 to 0.17 GPa).
The fracture behaviour of glaos
Revue des principaux phenomenes associes a la rupture du verre: pourquoi, normalement, la resistance n'est pas aussi elevee qu'elle devrait etre et que peut-on faire pour ameliorer les resistances pratiques; comment l'etude de la propagation des fissures macroscopiques aide a resoudre certains problemes mais en revele d'autres et comment sinon pourquoi, les particularites que l'on trouve sur les surfaces de fracture se produisent. La suggestion contestee que l'ecoulement pourrait jouer un role dans la fracture du verre est discutee
The Influence of Stamping Temperature on the Properties of a Glass Mat Thermoplastic Composite
The effect of varying the mold temperature on the mechanical properties of a stampable thermoplastic composite has been examined. A series of tensile, flexure and impact tests have shown that a distinct mold temperature dependency exists. This is most evident under impact loading conditions where it has been shown that the energy absorbing capacity of a material stamped at a low temperature is almost twenty-five percent lower than that of a similar composite molded at a much higher temperature. It is concluded that residual stresses resulting from the higher cooling rate may be in part responsible for this significant difference in impact resistance. It is also possible that greater damage occurred during the flow process in the lower temperature mold. A subsequent heat treatment cycle designed to simulate the passage of a component through a paint oven has been shown to improve quite significantly the energy absorbing capability of the material.