Contact loading dynamic

PHASE TRANSFORMATIONS IN MATERIALS UNDER DYNAMIC CONTACT LOADING... 

In particular, phase transformations under contact loading need a more detailed investigation. Both static and dynamic interactions between hard surfaces may result in phase transformations. Hydrostatic and deviatoric stresses must be taken into account and phase transformations in contact loading can be described as deformation-induced transformations. At the same time, the transformation pressures for silicon obtained in indentation tests are in good agreement with the results from high-pressure cell experiments, which utilize hydrostatic loading. 

Before testing, a contact load, is applied equal to 5% of the dynamic load that will be applied to the specimen. The haversine dynamic load, Tdynamicj to be applied should be such to obtain axial strains between 50 and 150 microstrain. 

Thus, the research work of Trifigny (2013) has consisted of observing the kinematics of the weaving process by checking aU the contacts and dynamic loads applied on yams. Based on these observations, the design of electrically sensitive and mechanically resistant sensor yams has been achieved, tested and calibrated. Then, dynamic measurements on the different loom locations have been conducted to detect the local distribution of elongation on different warp yams, especially applied on two different tow counts of continuous E-glass yams inserted into 3D warp interlock fabrics. 

PAPER IX(ii) Transient oil film thickness in gear contacts under dynamic loads... 

Transient Oil Film Thickness In Gear Contacts Under Dynamic Load. ... 

Sand slurry in a pipe is flowing at 6.5 m/s (21.3 ft/sec). The pipe diameter is 717 mm (28.35") pipe and the sand particle diameter d = 360 p,m (0.0142"). The volumetric concentration was presented to be 0.27. Upon review of the composition of the sand, it was noticed that 15% of the solids were fines smaller than 74 p,m. If the lower bed is packed at 60%, the contact load C = 0.30, and the Columbian friction factor is 0-50, determine the pressure gradient (assume water dynamic viscosity 1 cP, and sand S.G. 2.65). Volumetric concentration in the upper layer consists essentially of fines ... 

The often-cited Amontons law [101. 102] describes friction in tenns of a friction coefiBcient, which is, a priori, a material constant, independent of contact area or dynamic parameters, such as sliding velocity, temperature or load. We know today that all of these parameters can have a significant influence on the magnitude of the measured friction force, especially in thin-film and boundary-lubricated systems. 

C = basic dynamic load rating in kg or N (provided by the bearing manufacturer). It is the load which will give a life of 1 million revolutions P - equivalent dynamic bearing load in kg or N p = exponent of the life equation, which depends upon the type of contact between the races and the rolling elements. It is recommended as 3 for ball bearings and 10/3 for roller bearings = speed of the machine in r.p.m. 

One of the most interesting uses of emission spectroscopy is the study of the action of lubricants 162,166,167 168,169,170). A loaded steel ball is rotated in a fluid bath and made to slide over a diamond window. A contact region is formed which can be measured by the radiant power emitted. A substraction of the ball surface radiation from the total radiation emitted from the contact region was electronically carried out. A study of the emission spectra of a polyphenyl ether and a naphthenic fluid under dynamic conditions was made. The widths of some of the bands of the ether increased dramatically when a certain load (pressure) was exceeded. These increases were correlated with the changes of chemical composition through decomposition of the fluid 170,171). 

The proportionality constant /j, is the friction coefficient. A microscopic analysis shows that the friction force is, in fact, proportional to the true contact area that, in turn, is proportional to the load. The friction coefficient is in general higher for static than for dynamic friction. 

Recently, dynamic mode SFM has been used for genltle and more controlled surface modification [464,465]. Depending on the substrate type, the loading force was varied with ca. 500 nN amplitude at a frequency of 0.1-10 kHz. Force modulation SFM was employed to write on polycarbonate surfaces with letters ca. 50 nm high (Fig. 50b) as the tip was in light contact with the surface and a modulation frequency was relatively low to ensure plastic deformation of the polymer [464]. 

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