On the elastic and mixed-mode fracture properties of PVC foam

Sandwich structures are widely used for the design and fabrication of lightweight structural systems, due to their capability to exhibit excellent structural and thermal performances at low material usage. Understanding the phenomena of propagation of macro-cracks in the core and delamination at the face-to-core interface are aspects of great computational interest. Linking sophisticated models with the actual characterisation of their mechanical properties is essential in view of real engineering applications. The elastic and fracture characterisation of the materials composing the core is particularly relevant because its cracking affects the capacity of the sandwich structures to carry out transverse loads. In this work, PVC foams typically used as the inner core in structural applications are investigated over a range of foam densities. Firstly, the elastic properties of foams under compressive uniaxial loading are measured using a full-field methodology. Subsequently, SemiCircular specimens are tested in bending varying the position of supports to generate all range of mixed fracture modes. Suitable fracture criteria are also considered in order to assess their capability to evaluate fracture parameters in PVC foams. Finally, the parameters experimentally determined have been used to validate the response provided by a numerical model developed by the authors.