Table 3: Standard Linear Solid viscoelastic medium.

              Model Constitutive equation
        1 𝜀 = 𝐸 𝑣 1 + 1 𝐸 𝑣 2 1 1 + 𝜏 𝜕 𝑡 𝜎 ; the differential operator 𝜕 𝑡 𝜕 / 𝜕 𝑡

        Viscoelastic Operator that Corresponds to the Modulus of Elasticity 𝐸
                 1 𝐸 1 𝐸 𝑣 1 + 1 𝐸 𝑣 2 1 1 + 𝜏 𝜕 𝑡

              The modified Creep Model
         𝑢 ( 𝑡 ) 0 = 𝑏 𝜒 𝐸 𝑣 1 𝑃 0 𝐿 0 1 / ( 𝜒 + 1 ) Φ 2 1 , 1 𝜒 + 1 𝐸 𝜒 + 1 , 1 , 𝑣 1 + 𝐸 𝑣 2 𝜂 2 𝑡 𝑡 , 𝜏

             The modified Thermal Creep Model
     𝑢 ( 𝑡 ) 0 = 𝑏 𝜒 𝐸 𝑣 1 𝑃 0 𝐿 0 1 / ( 𝜒 + 1 ) Φ 2 1 , 1 𝜒 + 1 𝐸 𝜒 + 1 , 1 , 𝑣 1 + 𝐸 𝑣 2 𝜂 2 𝑡 𝑡 , 𝜏 𝑄 × e x p 𝑅 1 𝑇 1 𝑇 0 ,
where Φ 2 is the confluent hypergeometric function of two variables (Appell function)
              which is defined by:
       Φ 2 ( 𝛼 , 𝛽 , 𝛾 , 𝑥 , 𝑦 ) = 𝑚 = 0 𝑛 = 0 ( 𝛼 ) 𝑚 ( 𝛽 ) 𝑛 ( 𝛾 ) 𝑚 + 𝑛 𝑥 𝑚 𝑦 𝑛 𝑚 ! 𝑛 ! , and ( 𝑥 ) 𝑛 = ( 𝑥 + 𝑛 1 ) ! ( 𝑥 1 ) !