Added Viscoelastic_MR to templates

src/matadi/models/_templates.py

@@ -3,7 +3,7 @@
 from ._hyperelasticity_isotropic import neo_hooke
 from ._misc import morph
 from ._pseudo_elasticity import ogden_roxburgh
-from ._viscoelasticity import finite_strain_viscoelastic
+from ._viscoelasticity import finite_strain_viscoelastic, finite_strain_viscoelastic_MR
 
 
 class NeoHookeOgdenRoxburgh(MaterialTensorGeneral):
@@ -81,3 +81,26 @@ def fun(x, mu, eta, dtime):
             eta=eta,
             dtime=dtime,
         )
+
+class Viscoelastic_MR(MaterialTensorGeneral):
+    "Finite strain viscoelastic material formulation with Mooney-Rivlin hyperelasticity."
+
+    def __init__(
+        self,
+        c10 = 1,
+        c01 = 1,
+        eta = 1,
+        dtime=1,
+    ):
+        def fun(x, c10, c01, eta, dtime):
+            P, statevars = finite_strain_viscoelastic_MR(x, c10, c01, eta, dtime)
+            return P, statevars
+
+        super().__init__(
+            fun=fun,
+            statevars_shape=(6, 1),
+            c10 = c10,
+            c01 = c01,
+            eta=eta,
+            dtime=dtime,
+        )