Mechanical Properties and Dynamic Constitutive Model of Polyurethane Foam under Different Strain Rates

Polyurethane foam (PUF) is widely utilized in cushioning and energy absorption applications, owing to its cellular structure, that provides high damage tolerance under compression. This study explores the dynamic mechanical properties of PUF with varying densities under different strain rates. Uniaxial compression tests were conducted on PUF samples with densities of 120, 200, and 300 kg/m³ using an improved Split Hopkinson Pressure Bar (SHPB) system and a universal testing machine, with loading rates ranging from 10^–4 to 2000s⁻¹. Results show that PUF properties are influenced by density and strain rate. Higher density foams have higher strength but lower densification strain. All samples demonstrated strain rate sensitivity, where higher rates leading to increased strength and decreased densification strain. Based on the aforementioned findings, a dynamic constitutive model was developed to incorporate the influences of density, strain, and strain rate. This model effectively predicts the mechanical behavior of PUF and offers valuable insights for engineering applications requiring impact protection and energy absorption.