Changing elastic parameters during simulation

In order to obtain the true elastic parameters, it is necessary to change the elastic parameters during the simulation process and obtain them iteratively. May I ask how to modify the elastic parameters during the simulation process? Thank you!

Physical parameters

rho: 1075 #density of the model [kg/m3] material: NeoHookean #constitutive law, choose among [StVenantKirchhoff, NeoHookean, Corotated] E: 2850 #Young's modulus nu: 0.39 #Poisson ratio