Studies on Digital Shearography for Testing of Aircraft Composite Structures and Honeycomb-Based Specimen
This paper reviews shearography and its applications for testing of aircraft composite structures and honeycomb-based specimen. Shearography is a laser-based interferometry in conjunction with the digital imaging processing technique for full-field measurement of surface deformation. It reveals defects in an object by looking for defect-induced deformation anomalies. It does not require special vibration isolation, and with the development of a small and mobile measuring device (portable inspection system), it can be employed easily in field/factory environments.
Quality evaluation of rubber-to-metal bonded structures based on shearography
The quality of bonding is often a concern in rubber-to-metal bonded parts with regard to the integrity and stability of the structure. In this study, shearography has been used to detect the out-of-plane deformation of the defects caused by thermal and vacuum stresses. A sample of the vulcanized styrene-butadiene rubber bonded to steel with known artificial voids was prepared and during bonding process a region was glued with thick adhesives. The rubber surface of the sample was inspected in thermal radiation and vacuum modes respectively with a self-designed shearography device. Meanwhile, a numerical simulation was conducted to predict the out-of-plane deformation of the rubber surface in these two stress modes. Results from the numerical simulation and the experiments indicated that the debonding defects could be inspected in both loading modes. In the thermal radiation mode the region with thick adhesives could be identified successfully. This study provides a guideline for quality control of rubber-to-metal structures using an optical method.
Corporations and the Market for Law
The state competition for corporate law has long been studied as a distinct phenomenon. Under the traditional view, corporations are subject to a unique choice-of-law rule, the internal affairs doctrine (IAD). This rule is explained as a historical accident, or by the special logistics of the corporate contract. The resulting market for corporate law appears to have special characteristics, particularly including the dominance by the single state of Delaware. This paper challenges the traditional view. It shows that the corporate law market is best understood as a special application of the general market for law. Any differences are matters of degree rather than kind, and are explained by considerations underlying enforcement of all choice-of-law contracts rather than by factors unique to corporations. It follows that theories of corporate competition that ignore the broader law market context are incomplete, and that the competition for corporate law carries lessons for the law market generally. Moreover, the connection between the corporate and other law markets has implications for the nature of corporate law, the constitutional status of the IAD, the scope of the IAD, and for the relationship between state and federal law.