Tapered Double Cantilever Beam Fracture Tests of Phenolic-Wood Adhesive Joints

Tapered double cantilever beam specimens were developed and used to test the effects of bondline thickness, wood anisotropy, and cure time on the fracture energy of phenolic-wood adhesive joints. Fracture, energy, G10, increases slowly with bondline thickness (in the range 160-100 microns) then jumps considerably (100-90 microns), and finally drops sharply at bondline thicknesses less than 70 microns. As the grain orientation with respect to the bonded surface (grain angle) is increased from zero degrees, G10 decreases and goes through a minimum at about 20 degrees grain angle. At larger grain angles, G10 increases. The fracture energy also increases strongly with cure time, reaching a plateau at long cure times

Competition After Unbundling: Entry, Industry Structure, and Convergence

In the last few years, U.S. telecoms policy has shifted from encouraging the sharing of existing networks to facilitating the deployment of advanced communications networks. Given the large capital expenditures required for these networks, there can be only a few of such networks. In light of the natural forces that limit the number of facilities-based suppliers, it is vital for policymakers to investigate and implement rules that make markets more conducive to facilities-based entry and eliminate any existing rules that discourage deployment. The purpose of this Article is to provide a simple conceptual framework to evaluate the effect of particular rules and regulation on the construction of advanced communications networks and the expansion of existing networks into new markets. We provide numerical examples and a number of applications to illustrate how the conceptual framework implicates particular rules and regulations as to their effect on facilities-based entry. Applications include an analysis of convergence, regulated limitations on service offerings, the pernicious effects of cable franchising, and the potential for collusion

Tapered Double Cantilever Beam Fracture Tests of Phenolic-Wood Adhesive Joints: Part II. Effects of Surface Roughness, the Nature of Surface Roughness, and Surface Aging on Joint Fracture Energy

Tapered double cantilever beam specimens were used to test the effect of surface roughness, the nature of surface roughness, and surface aging on the fracture energy of phenolic-wood adhesive joints. The fracture energy and the failure characteristics of the joints were found to depend not only on the surface roughness but also on the method of surface preparation. The fracture energy increased monotonically with surface roughness for specimens derived from hand-sanded surfaces but exhibited a minimum for specimens obtained from machine-sanded surfaces. Generally, joints from hand-sanded surfaces had higher fracture energies than those derived from the machine-sanded surfaces. Within the joints derived from the machine-sanded surfaces, those sanded perpendicular to the direction of crack growth had higher fracture energies than those sanded parallel to the direction of crack growth. Aging surfaces prior to bonding significantly decreased adhesive joint strength.Notwithstanding the differences in roughness, microscopic examination revealed little difference in the appearance of the sanded surfaces. Adhesive did not penetrate hand-sanded surfaces to any appreciable extent, but did deeply penetrate both the vessel and fiber lumens on the machine-sanded surfaces. Microscopic examination of the fractured surfaces did reveal significant differences that related to the fracture toughness of the bond

Competition After Unbundling: Entry, Industry Structure, and Convergence

In the last few years, U.S. telecoms policy has shifted from encouraging the sharing of existing networks to facilitating the deployment of advanced communications networks. Given the large capital expenditures required for these networks, there can be only a few of such networks. In light of the natural forces that limit the number of facilities-based suppliers, it is vital for policymakers to investigate and implement rules that make markets more conducive to facilities-based entry and eliminate any existing rules that discourage deployment. The purpose of this Article is to provide a simple conceptual framework to evaluate the effect of particular rules and regulation on the construction of advanced communications networks and the expansion of existing networks into new markets. We provide numerical examples and a number of applications to illustrate how the conceptual framework implicates particular rules and regulations as to their effect on facilities-based entry. Applications include an analysis of convergence, regulated limitations on service offerings, the pernicious effects of cable franchising, and the potential for collusion