STRESSES AND DEFORMATIONS IN MULTI-PLY AIRCRAFT TIRES SUBJECT TO INFLATION PRESSURE LOADING.
Technical rept. Aug 68-Dec 69,
AIR FORCE FLIGHT DYNAMICS LAB WRIGHT-PATTERSON AFB OHIO
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The pneumatic tire casing is treated as a laminated, anisotropic, toroidal shell of revolution possessing bending rigidity. The plies are considered to be homogeneous orthotropic laminae on a macroscopic scale, which are constructed of elastic textile cords embedded in an elastic rubber matrix. Modern micro-mechanics theory, which is based on the self-consistent model of composite materials, is used to calculate the four basic elastic moduli of a single lamina. The tire shell is considered to deform according to the classical Love hypothesis. The equilibrium, strain-displacement, and laminate constitutive equations governing the tire shell are reduced to a system of six first order ordinary differential equations with variable coefficients. A multi-segment, forward integration technique is used which first transforms the two point boundary value problem into an equivalent set of initial value problems which can then be integrated numerically with a fourth order Runge-Kutta routine. The finite displacements are taken into account by an incrementing process which builds up the total solution as sequence of linearized solutions. The theory and solution technique is illustrated by means of a numerical example. The tire chosen for this purpose is a 32 x 8.8 Type VII aircraft tire. A complete set of numerical data is presented. The calculations were verified experimentally by measuring tire strains and the inflated tire meridian profile. The agreement between theory and experiment is good. Author