The strain energy density function equals the Helmholtz. 應變能密度函數等于亥姆霍茲函數。
Multiaxial fatigue life prediction methods are concentrated, in which critical-plane strain energy density criteria seem to be the most promising. 主要評述各種多軸疲勞壽命估算方法,其中臨界面應變能密度法是較為有效的方法。