Contact condition

Adhesion between layers of plastic sheets in contact condition arises during storage or use when components are under pressure. 

Some explanations could be possible for these contradictory results. One is that a various types of CNTs may be obtained by different methods, since SWCNTs as much as 50 % are chiral and nonmetallic [42]. The other is that the result may be attributable to the contact condition of SWCNT bundles. When the bundles closely contact each other, the SWCNT system will likely become a three-dimensional one just as in the case of contacted MWCNTs. 

Zhou, L., Kato, K., Vurens, G., and Talke, F. E., The Effect of Slider Surface Texture on Flyability and Lubricant Migration under Near Contact Conditions, Tribal. Int., Vol. 36, No. 4-6,... 

The existence of asperity contacts in mixed lubrication causes great many local events and significant consequences. For example, the parameters describing lubrication and contact conditions, such as film thickness, pressure, subsurface stress, and surface temperature, fluctuate violently and frequently over time and space domain. It is expected that these local events would have significant effects on the service life of machine elements, but experimental measurements are difficult because of the highly random and time-dependent nature of the signals. Only a few successes were reported so far in experimental studies of mixed lubrication, mostly limited to the artificially manufactured... 

Product Information Sheet No. 212 , Sandwich, Pfizer Chemicals, 1969 Calcium or its alloys react violently with water (or dilute acids) and the heat of reaction may ignite evolved hydrogen under appropriate contact conditions. 

In contact with air, the fluoride ignites or explodes, depending on contact conditions. Heated sodium ignites in the gas. 

Groendes and Mesler (1982) studied the saturated film boiling impacts of a 4.7 mm water droplet on a quartz surface of 460 °C. The fluctuation of the surface temperature was detected using a fast-response thermometer. The maximal temperature drop of the solid surface during a droplet impact was reported to be about 20 °C. Considering the lower thermal diffusivity of quartz, this temperature drop implies a low heat-transfer rate on the surface. Biance et al. (2003) studied the steady-state evaporation of the water droplet on a superheated surface and found that for the nonwetting contact condition, the droplet size cannot exceed the capillary length. 

The situation is more complex when various other ingredients are added to PBT. Glass fibers, for instance, may lose adhesion from the resin due to the action of water on the glass-PBT interface, independent of the PBT-matrix reaction. This action will depend on specific contact conditions such as time, temperature and pH. In some instances, fiber-to-matrix adhesion can be recovered when the sample is dried, resulting in the recovery of some mechanical properties (if the PBT matrix is not too severely degraded). Other additives can introduce additional complications. 

The contact condition found (5.14) is essential for a theory of ignition. The necessary condition for ignition is that, at a surface temperature TB, the gradient should not exceed the value which corresponds to the contact of the curves tpc. At the point C we find from (5.8) and (5.14)... 

The basic theories of elastic deformations associated with various contact forces under static contact conditions have been introduced in the last section. Assuming that an impact process of two solids can be regarded as quasi-static, the theories given in 2.3 are used directly to link the dynamic deformations of the colliding solids with the impact forces. In this section, the collisions of elastic spheres are described. 

The essential material property of rubbers is their low elastic modulus, which ensures that the contact deformation remains elastic over a very wide range of contact conditions. The abrasive wear of rubbers is due to either fatigue of the material or tearing by a cutting force from impacts with sharp-edged particles. 

The boundary resistance R is dominated either by the space charge resistance in the current direction or the proper charge transfer resistance through the boundary core (Part I, Section VI.6). (Resistance effects due to laterally inhomogeneous contact conditions are discussed in Section III.9). 

Until today, the control of transfer from plastics packaging materials into foods has mainly been based on the measurement of the substance(s) in the food or simulant after certain specified, and in most cases standardized, contact conditions. Here, in principal, it can be distinguished between ... 

Therefore, the scope of the method seems to be limited only to very short and mild contact conditions in the case of aqueous food simulants, but the method is fully applicable to olive oil and other oils or fats as well as to non-proton-active alternative simulants such as iso-octane. 

Contact Conditions Under Small Amplitude Micromotions. 163... 

These observations underline the strongly intricate interactions between particle detachment, third body rheology and evolving contact conditions which are inherent to wear processes in many macroscopic contacts. 

Fig. 4 Brittle failure modes of polystyrene within contacts, a Poly(styrene) film on a poly(methylmethacrylate) substrate. The regular crack pattern is induced by the sliding of a glass sphere under elastic contact conditions, b Poly(styrene) under viscoplastic scratching by a cone indenter (from [40])...

The establishment of the interrelationships between polymer fracture properties and contact fatigue behaviour requires some knowledge of the contact stress field. The specificity of fretting loading is that, depending on the applied contact load and imposed relative displacement, two different contact conditions can be achieved within the interface [54,55] (Fig. 5) ... 

Fig. 5 Schematic description of the contact conditions encountered under small amplitude cyclic lateral micro-motions (fretting). S is the applied lateral displacement, Q is the lateral force and P is the applied constant normal load. The elliptic and trapezoidal Q(S) loops correspond to partial slip and gross slip condition respectively...

This combined analysis of AoA and Ar, therefore establishes that the main cracks that nucleate close to the contact edge correspond to predominantly tensile fatigue cracks. This conclusion remains valid whatever the contact condition (partial slip or gross slip). In addition, the distribution of within the contact plane is of interest (Fig. 15). The maximum amplitude... 

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