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).
Mechanical Strength of Microstructured Optical Fibers
An experimental study of the mechanical reliability of microstructured optical fibers (MOFs) is reported. Tensile tests were carried on five types of MOFs and two reference fibers, and the tensile strengths were analyzed using Weibull statistics. Optical microscopy of the surfaces of rupture allowed identifying the critical flaws and determining the failure mechanisms. First, it appears that the MOFs have lower tensile strengths than standard optical fibers. Second, the mechanical strength of MOFs was found to be related to the dimensions and morphology of the microstructure. Finally, fractographic examinations confirmed that MOFs can fail from defects located in the vicinity of the air holes, in contrast to standard optical fibers for which cracks always start propagating from defects located on the outer silica surface.
The Impact of EU Unfair Contract Terms Law on U.S. Business-to-Consumer Internet Merchants
When the Court of Appeals for Versailles issued its decision in AOL France v. UFC Que Choisir2 in September 2005, it sent the message to U.S. Internet businesses that even contractual boilerplate localized for European markets may be invalid in European consumer transactions. In that case, a French consumer advocacy group challenged the terms AOL offered its French customers after AOL had made extensive revisions to its standard form contracts to respond to the concerns regarding those terms expressed in an advisory opinion by a French consumer protection agency. In 2004, a trial court invalidated nearly every term in the revised agreement; the appeals court affirmed on all counts. Subsequently, in July 2006 following concerns raised by the Office of Fair Trading (“OFT”), a United Kingdom government agency charged with “making sure markets work well for consumers,”3 Dell Corporation Limited changed its online terms and conditions to make them fairer to consumers.4 European consumer contract law had an impact in both cases. At issue for AOL France and Dell Corporation Limited was the application of France’s and the UK’s consumer contract law which is based on the Unfair Contract Terms Directive of 19945 and calls into question the validity of many of the terms that U.S. courts routinely enforce in transactions involving American consumers and merchants.