Digital image correlation is utilized to characterize deformation and strain fields developed within the layers of density-graded multilayered foam structures subjected to uniaxial quasi-static and dynamic compression. Three-layered graded structures fabricated from rigid polyurethane foams with nominal densities of 160, 240, and 320 kg/m³ are subjected to both quasi-static and dynamic loading. The quasi-static measurements show that, irrespective of the loading direction, the densification initiates in the lowest density layer and propagates into other layers later once the first layer is fully densified. The deformation mechanisms are seen to be different in the case of dynamic loading conditions compared to the quasi-static loading. The deformation mechanism, in the case of dynamic loading, depends on the sample orientation relative to the direction of the applied load. In cases where the higher density layers are impacted, the propagation of the elastic and compaction waves leads to partial deformation of the lowest density layer. Sample deformation continues in all layers upon the reflection of the stress waves from the distal end of the sample. In cases where the lowest density layer is oriented towards the impact face, a completely different deformation response is observed. A detailed full-field analysis of strain and stress is performed. The mechanisms associated with the formation and propagation of stress waves from the impact ends to the distal ends of the samples are discussed.

利用数字图像相关来表征在经受单轴准静态和动态压缩的密度渐变多层泡沫结构层内形成的形变和应变场。由硬质聚氨酯泡沫制成的三层渐变结构，标称密度为160、240和320 kg / m ³承受准静态和动态载荷。准静态测量表明，无论加载方向如何，致密化均始于最低密度的层，并在第一层完全致密后传播到其他层。与准静态载荷相比，动态载荷条件下的变形机理不同。在动态载荷的情况下，变形机制取决于样品相对于所施加载荷方向的方向。在高密度层受到冲击的情况下，弹性波和压实波的传播导致最低密度层的部分变形。在来自样品远端的应力波反射后，样品变形在所有层中继续。在最低密度层朝向冲击面的情况下，观察到完全不同的变形响应。进行了详细的应变和应力全场分析。讨论了与从冲击端到样品远端的应力波的形成和传播相关的机制。