Lifetime Predictions for High-Density Polyethylene under Creep: Experiments and Modeling.

Area of Science:

• Materials Science
• Polymer Physics
• Mechanical Engineering

Background:

• High-density polyethylene (HDPE) exhibits complex viscoelastoplastic behavior under mechanical stress.
• Understanding this behavior is crucial for predicting material performance and lifetime.

Purpose of the Study:

• To develop and validate a constitutive model for the viscoelastoplastic response of HDPE.
• To accurately predict the long-term behavior and failure of HDPE under creep conditions.

Main Methods:

• Uniaxial tensile tests, relaxation tests, and creep tests were conducted on HDPE at room temperature.
• A seven-parameter viscoelastoplastic model was developed and calibrated using experimental data.
• Numerical analysis was employed to validate the model's predictive capabilities against independent creep tests.

Main Results:

• The developed constitutive model accurately captures the viscoelastoplastic response of HDPE.
• The model successfully predicted short- and medium-term creep behavior.
• The model's application allowed for the evaluation of HDPE lifetime under creep, incorporating the creep endurance limit.

Conclusions:

• The proposed viscoelastoplastic model provides a robust framework for analyzing HDPE behavior.
• The model's ability to predict stress-time-to-failure diagrams enhances its practical applicability.
• This approach offers valuable insights into the creep endurance limit of semicrystalline polymers.