AN ORTHOGONAL UNIFORM/PARABOLIC SURFACE PRESSURE HALF-SPACE ELEMENT FOR THE ANALYSIS OF NON-HERTZIAN CONTACT
An orthogonal uniform/parabolic surface pressure half-space element is derived for the analysis of non-Hertzian contact. Restriction is made to parabolic variation of the surface gap in the contact in one orthogonal direction. The surface pressure is integrated analytically over the surface element to obtain influence co-efficeints, e.g. for the normal surface displacement. The coefficients are assembled into matrices leading to a linear system of equations. After solving the parabolic pressure variation is transformed to an equivalent semi-elliptic one coinciding with Hertzian line contact. Adjustments are introduced to approximate the finite size of the bodies in contact. The theoretical predictions are compared to experiments involving the non-Hertzian contact between cylinders of finite lengths.
Pressure between elastic bodies having a slender area of contact and arbitrary profiles
Abstract A numerical method is presented for calculating the pressure distribution and contact area shape between two elastic bodies of arbitrary profile which make contact over a slender contact area, i.e. where the relative curvature of the two profiles is much smaller in the longitudinal direction than in the transverse. The pressure distribution is assumed to be piecewise-linear in the longitudinal direction and semi-elliptical in the transverse. No a priori relationship is assumed between the shape of the contact area and the longitudinal variation in pressure; they are found simultaneously from dual integral equations for the compatibility of (a) the normal displacement and (b) the transverse curvature along the longitudinal axis of the contact zone. In cases where the profiles of the contacting bodies are smooth and continuous up to, and beyond, the ends of the contact area, the method gives a very reliable measure of the contact pressure distribution. Where discontinuities in profile are present, at roller ends for example, stress singularities are to be expected and like any numerical method, only approximate values of the stress concentration can be found. In the cases studied, the concentration of pressure associated with a “sharp” edge of contact is found to be very local. The method has been applied to both cylindrical and variously “crowned” rollers, also to a ball “over-riding” the edge of a closely conforming groove.
PASSIVE AND LOW-ENERGY RESEARCH AND PRACTICES-DEHUMIDIFICATION
Methods of achieving acceptable indoor conditions in overheated, temperate, and underheated humid climates are discussed and compared. Desiccants and desiccant systems utilizing solid and liquid sorbents and various low-energy mechanical systems are described and evaluated.