Atomic force microscopy (AFM) is an established approach to map nanoscale mechanical properties because of its high spatial resolution and sensitivity. However, the data obtained from AFM mechanical property measurements on heterogeneous materials is often convoluted with the mechanical properties of the substrate, i.e., the "substrate effect." The substrate effect arises from a structural stress field due to the rigid body in addition to the intrinsic mechanical properties of matrix and interphase. The substrate effect thus confounds AFM mechanical property measurements near surfaces. Several computational approaches have been proposed to extract interphase properties from AFM indentation measurements, but the experimental validation of these approaches has not yet been sufficiently established. For example, Brune, et al., combined finite element analysis (FEA) with high resolution AFM to characterize the complex interphase between a rubber and a silicon substrate. They evaluated several interphase models via FEA and found an interphase model that can explain the stiffness gradient obtained from the experiment. However, their approach requires iterative adjustment between simulation and experiment and makes assumptions about the modulus gradient of the interphase and, additionally, requires significant computational resources.