Data interpretation adhesion force

The occurrence of areas of high and low adhesive forces, which are oriented parallel to the PVA fiber axis, can be attributed to an increased and decreased effective contact area between the side of the tip as compared to the tip apex. As the fiber shape is not a priory known, no definite conclusions about the chemical contrast can be obtained. However, a careful comparison of topography and force data clearly reveals the artifact. These observations demonstrate that force maps, and force data in general, must be interpreted carefully. In particular, attention must be paid to avoid coupling of the topography into the force images. 

The work of Gordano et al. [42] suggests that a number of factors might influence the adhesion of particles to membranes, including electrostatic interactions, van der Waals forces, short-range interactions, surface roughness, and membrane deforma-bility. For quantitative interpretation of data, the influence of each of the important factors must be considered. 

Fig. 7.8. Changing stress experienced by a steel lap joint as the load is progressively increased. Load (kN) A, 112 B, 100 C, 84 D, 68 E, 56 F, 44 G, 32 H, 20 I, 8 J, 4 K, 1. Joint as Fig. 7.6. Adhesive epoxide (half joint only displayed). The interpretation of computer generated data such as this does need care, for in practice the combination of the approach of the adhesive to its asymptotic (ultimate) shear stress coupled with the elastic/plastic deformation of the joint s thin sheet steel will normally cause adhesive failure of the adhesive, due to tensile forces induced by cleavage. If, in reality, adherend distortion is suppressed then the steel itself fails — not the adhesive This could be expected in the region of loads E-F. However, the computer model has been run on to illustrate the sort of load transfer, towards the inner areas of the joint, which might be anticipated for heavy steel section symmetrically loaded and not...

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