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.

在这项工作中，对聚合物泡沫热成型、泡沫注射成型、珠粒发泡和薄膜发泡进行了审查，以探索制造用于汽车应用的复杂几何结构的夹层结构的可行工艺。注塑泡沫通常具有高密度、差的泡孔形态和不必要的表层。目前可用的可发泡薄膜是压力诱导的。可发泡薄膜要产生泡沫，需要施加较高的均匀分布压力，这使得用可发泡薄膜制造三维复杂几何形状的泡沫部件变得困难。大多数商用高性能泡沫芯材都可以热成型。理想情况下，如果使用高性能泡沫板，热成型泡沫芯将具有良好的机械性能。然而，在热成型过程中，泡沫的机械性能可能会降低，尤其是在拐角处。珠粒发泡为要模制的泡沫几何形状提供了高度的自由度，并且在模制过程中可以将插入物集成到泡沫芯中。此外，可以用不同密度的泡沫珠制造高应力区域密度高而低应力区域密度低的泡沫芯。然而，由于不均匀的熔合度以及珠粒之间的弱键和空隙，珠粒泡沫通常显示出低于其对应块的机械性能。相对而言，使用高性能泡沫板进行热成型和使用高性能泡沫珠粒成型，对于大规模生产用于汽车应用的复杂几何形状的夹心芯具有巨大的潜力。然而，