A review on manufacture of polymeric foam cores for sandwich structures of complex shape in automotive applications

Abstract

In this work, polymeric foam thermoforming, foam injection moulding, bead foaming and film foaming were reviewed in an effort to explore feasible processes to manufacture sandwich structures of complex geometry for automotive applications. Injection moulded foams generally suffer from high density, poor cell morphologies and unnecessary skin layers. Foamable films currently available are pressure-induced. In order for foamable films to produce foam, high uniformly-distributed pressure needs to be applied, which makes it difficult to manufacture foam parts of three-dimensional complex geometry with foamable films. The majority of commercial high-performance foam cores can be thermoformed. Ideally, thermoformed foam cores would have good mechanical properties if high-performance foam sheets are used. However, the mechanical properties of foams might be reduced during the process of thermoforming, especially around corners. Bead foaming offers a high level of freedom in foam geometry to be moulded, and inserts can be integrated into foam cores during the process of moulding. Moreover, foam cores with high density in high stressed areas and low density in low stressed areas can be manufactured with foam beads of different densities. However, due to nonhomogeneous degree of fusion and weak bonds and voids between beads, bead foams generally show mechanical properties lower than their block counterpart. Relatively speaking, thermoforming with high-performance foam sheets and moulding with high-performance foam beads hold great potentials for mass production of sandwich cores of complex geometry for automotive applications. However, further investigation on the mechanical properties of thermoformed foams and high-performance bead foams is still in need to confirm their suitability.

A Review of the Preparation of Porous Fibers and Porous Parts by a Novel Micro-Extrusion Foaming Technique

“…Owing to heightened environmental concerns and increased awareness, the physical foaming technique for polymers has garnered significant attention and witnessed substantial development since its inception. Various foaming techniques have been developed for manufacturing plastic and elastomeric foams, with the main ones being batch foaming [ 65 , 77 , 78 ], injection molding foaming [ 65 , 79 , 80 ], and continuous extrusion foaming [ 65 , 81 , 82 ]. In recent years, in pursuit of shape-unrestricted polymer foams, polymer physical foaming technology has been employed in 3D printing, giving rise to the emergence and advancement of MEF.…”

Mechanically Robust Foamed Polypropylene/Bamboo Powder Composite Basketworks by CO2 Extrusion Foaming

“…Herein, it is necessary to design the cellular structure of PP-based composite basketworks. Typically, a sandwich structure with both solid and cellular structures can not only save materials used but also improve their mechanical properties, which has wide potential applications in transportation, marine, aerospace, energy absorption, etc. − High-performance sandwich structures have consistently attracted a lot of attention from both scientists and the industry. Zhou et al.…”

Dual-phase-lag thermoelastic damping analysis of a functionally graded sandwich micro-beam resonators incorporating double nonlocal effects

“…Nowadays, sandwich structures have been widely used in various engineering fields such as aerospace, civil engineering and automotive field due to their high strength and excellent vibration resistance. 1 However, the traditional sandwich structures typically exhibit delamination and stress concentration at the interfaces, which is caused by the material discontinuities. The above imperfections can be avoided by applying functionally graded (FG) sandwich structures.…”