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Dynamic modulus is the ratio of stress to strain under ''vibratory conditions'' (calculated from data obtained from either free or forced vibration tests, in shear, compression, or elongation). It is a property of viscoelastic materials. == Viscoelastic stress–strain phase-lag == Viscoelasticity is studied using dynamic mechanical analysis where an oscillatory force (stress) is applied to a material and the resulting displacement (strain) is measured.〔(PerkinElmer "Mechanical Properties of Films and Coatings" )〕 *In purely elastic materials the stress and strain occur in phase, so that the response of one occurs simultaneously with the other. *In purely viscous materials, there is a phase difference between stress and strain, where strain lags stress by a 90 degree ( radian) phase lag. *Viscoelastic materials exhibit behavior somewhere in between that of purely viscous and purely elastic materials, exhibiting some phase lag in strain.〔Meyers and Chawla (1999): "Mechanical Behavior of Materials," 98-103.〕 Stress and strain in a viscoelastic material can be represented using the following expressions: *Strain: *Stress: 〔 where : where is frequency of strain oscillation, : is time, : is phase lag between stress and strain. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「dynamic modulus」の詳細全文を読む スポンサード リンク
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