For a type of functiona 且 ] y graded materials , volumetric fraction of particles varies continuously and extensively . in general, because particles are randomly distributed , it is diMcult to accurately evaluate the properties and to a( 加 st them . Aconcise evaluation of the properties is needcd for materia ]design . In the present paper, plates including an array of particles are dealt with and the relations between stress and strain under uniaxial tension are discussed . The plate specimens

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... are made of cpoxy resin and steel balls , with different volumetric fraction of steel balls . From the resu [ t of the tensile test, it is clarified the influence ofvolumetric fraction ofba11s on the stress − strain relations ofthe specimens . In addition , tangent coefficients of stress − strain curves are obtained and it is shown the change of the tangent coe 伍 cients with strain . The maximum tangent coefflcients are compared with values obtained by Voigt ' s, Reuss ' and the intermediate models . Also tangent coeMcients at O5 % strain are compared with values obtained by considering effective section .