Meaning
Predicting the multi-axial deformation of polymer components under high loads requires a mathematical framework that incorporates both stress-dependent and time-dependent behaviors. The schapery model provides this framework, utilizing thermodynamics to describe how stress accelerates the rate of molecular relaxation and creep in viscoelastic materials. It establishes the limits of linear viscoelastic theory by introducing stress-dependent factors that adjust the material’s internal timescale.
This model is a standard tool for designing plastic components that experience high-stress environments.
Parameter Calibration
Calibrating the material parameters requires a series of creep and recovery tests conducted at multiple stress levels. In the schapery model, these parameters include non-linear factors that modify the elastic and transient compliance. If the tests are conducted across too narrow a stress range, the model will fail to predict the onset of rapid creep under high loads.
This calibration ensures the simulation matches physical tests.
Creep Prediction
Non-linear creep behavior must be evaluated to ensure that plastic parts do not deform beyond acceptable limits during their service life. The model predicts the non-linear relationship between stress and strain over time. It prevents premature component failure.
Analysis Integration
Mechanical engineers integrate this model into finite element software to run complex structural simulations. This integration allows for the design of lighter parts without sacrificing mechanical reliability. This modeling is standard in the automotive industry.
