Linear is a special purpose material method that distributes stress forces within the material in a linear manner. Linear elasticity is only valid for materials or stress states in materials that does not produce yielding (plastic deformation). Due to its linear nature of this material property it is easy to get this material to “explode” or even create infinite results. Such borderline mathematics are usually only kept in check by increasing the accuracy of the calculations (Sub-Frame Samples).
In general, this linear elasticity method is meant to reproduce a simplified representation of elastic materials and their behavior under stress.

Stiffness - defines the overall “rigidness” or stiffness of the material. As always, all MPM simulation are heavily dependent on Cell Size. A proper balance between Cell Size and Stiffness prevents explosive behavior or and simulation artifacts. Explosive behavior can always be counteracted by increasing the amount of simulation sub-step in the solver.

Volume Conserv. - this is one of the most important parameters to affect the look or behavior of the simulation. A theoretical value of 0.5 (not recommended) will keep the volume constant even when the material experiences stretching. Lower values will allow the material to freely stretch and distribute stress within the material's volume.