Table 1: Maxwell viscoelastic medium.

              Model Constitutive equation
        ( 𝜕 𝑡 / 𝐸 + 1 / 𝜂 ) 𝐹 = ( 𝜕 𝑡 ) 𝑢 ; the differential operator 𝜕 𝑡 𝜕 / 𝜕 𝑡

        Viscoelastic Operator Corresponds to the Modulus of Elasticity 𝐸
                1 𝐸 1 𝐸 𝜕 𝑡 + 1 / 𝜏 𝜕 𝑡

              The modified Creep Model
   𝑢 ( 𝑡 ) 0 = 𝑏 𝜒 𝐸 𝑃 0 𝐿 0 1 / ( 𝜒 + 1 ) 𝑒 𝑡 / 𝜏 × 1 𝐹 1 2 + 𝜒 𝑡 1 + 𝜒 ; 1 ; 𝜏 , 1 𝐹 1 [ 2 + 𝜒 / 1 + 𝜒 ; 1 ; 𝑡 / 𝜏 ] is the confluent
        hypergeometric function (called Kummer’s equation) written as:
   1 𝐹 1 𝑐 [ 𝑐 ; 𝑑 ; 𝑥 ] = 1 + 𝑑 𝑥 + 𝑐 ( 𝑐 + 1 ) 𝑥 2 + 𝑑 ( 𝑑 + 1 ) 2 ! 𝑐 ( 𝑐 + 1 ) ( 𝑐 + 2 ) 𝑥 3 𝑑 ( 𝑑 + 1 ) ( 𝑑 + 2 ) 3 ! + , or 1 𝐹 1 [ 𝑐 ; 𝑑 ; 𝑥 ] = 𝑛 = 0 ( 𝑐 ) 𝑛 ( 𝑑 ) 𝑛 𝑥 𝑛 𝑛 !