Analysis of Stress Distribution in SHOFU Zirconomer using cdmHUB Estimates Against Experimental Cyclic Loading

Abstract

This study investigates the predictive accuracy of the Composites Design and Manufacturing HUB (cdmHUB), a cloud-based micromechanics platform, in simulating the compressive behavior of Zirconomer. The primary objective is to determine if virtual "bottom-up" modeling can reliably predict fatigue failure and stress distribution as observed in experimental cyclic loading. The study utilized a dual-track approach:Computational Phase: We employed the Mori-Tanaka (MT) homogenization scheme on cdmHUB to calculate the effective elastic properties of a composite consisting of a polyalkenoate matrix (f=4.5GPa) reinforced with 10% volume fraction (Vf) zirconia particles (F=210 GPa). Structural analysis was conducted using the SwiftComp solver to map Von Mises stress distributions. Experimental Phase: Specimens of SHOFU Zirconomer (n=15) were fabricated (6x4mm cylinders) and stored for 24 hours at 37oC. Dynamic fatigue testing was performed using a Universal Testing Machine (UTM) at a frequency of 1.0 Hz for 500,000 cycles, with loads ranging from 50 N to 250 N. The cdmHUB simulation predicted a static compressive strength of 295.4 MPa, while experimental UTM results yielded a mean strength of 278.5 ± 12.3 MPa, representing a narrow deviation of 6.1%. Analysis of the Stress Distribution Map revealed that peak stresses were concentrated at the poles of the zirconia inclusions, aligning with the "interfacial debonding" failure modes observed in SEM micrographs of the experimental samples. However, a "deviation gap" was identified as zirconia content increased; at 20% Vf , the prediction error rose to 16.3%. This is attributed to the computational model's assumption of perfect particle dispersion, which contrasts with the physical agglomeration and micro-porosity typically encountered in high-viscosity hand-mixed cements. Furthermore, the S-N Curve demonstrated that while Zirconomer exhibits high static strength, its long-term endurance limit settles near 180 MPa, a critical threshold for clinical design. This research validates cdmHUB as a high-fidelity diagnostic tool for dental material prototyping. With a 94% accuracy rate for standard formulations, micromechanics simulations can effectively reduce the reliance on destructive testing during the initial stages of material design. Future iterations should incorporate time-dependent maturation kinetics to account for the dynamic chemical setting of glass ionomers.