Foldcores made of thermoplastic materials: Experimental study and finite element analysis

• A manufacturing process for thermoplastic foldcores was established.
• Mechanical properties of PET and PEEK foldcores were tested and compared.
• A FE modeling protocol for PEEK foldcores was developed.
• A parametric study on the mechanical properties of PEEK foldcores was performed.
• The mechanical properties of a PEEK and aramid foldcores were compared.

Foldcore sandwich structures have aroused considerable research interests in recent years as a promising alternative to honeycomb sandwich structures. While metallic, aramid and CFRP foldcores have been extensively studied, foldcores made of thermoplastic materials have not been well investigated. This paper presents an experimental and numerical study on thermoplastic foldcores. A manufacturing process involving folding with dies and shape-setting by heat-treatment was established. Both PET and PEEK foldcore specimens were successfully manufactured using this process and tested in compression. An explicit FE modeling protocol of PEEK foldcores were developed and validated with the test results. Furthermore, a parametric study on the weight-specific mechanical properties of various PEEK foldcore models subjected to virtual compression and in-plane shears was performed, through which the relationships between the mechanical properties and the geometric parameters were established. Finally, the mechanical properties of a PEEK model and its aramid counterpart with the same geometry were compared. It was shown that the PEEK foldcore has comparable or even better energy absorption performances than the aramid one.