Most products in automotive, aerospace, and household appliance industry are multi-material structures. Materials are connected through a variety of joining techniques with the aim of optimizing performance during production and operation phase. However, during recycling in the end-of-life phase, different materials combined in multi-material structures need to be liberated, e.g. disconnected, and separated again to enable high material recoveries. Typical recycling approaches use shredding technologies to liberate materials. Efficient material liberation contributes to achieving high recycling rates for end-of-life products set by the European Union, thereby reducing the need for primary resource extraction and leading to a more sustainable development.

To characterize material liberation, we conducted an experimental shredding study with multi-material lightweight structures typical for automotive A-frames consisting of steel and composite materials, which were shredded in two sequences in a pilot rotary shear. We characterized feed and resulting progeny particles through a set of quantitative and qualitative metrics, thereby tracking changes in joint characteristics, material composition and particle sizes over the course of two processing steps. We found that material liberation is dependent on many design and shredding parameters. Our characterization approach for feed and progeny particles allows for linking design parameters to liberation behaviour. Due to high variability of design and shredding parameters experimental data acquisition is effortful. Therefore, we present an outlook on first results of our physics-based, numerical simulation model using Finite Element Method. Once validated, shredding simulations of many design configurations shall inform the designer about the liberation behaviour of a multi-material structure, such as the A-frame specimens.

汽车、航空航天和家用电器行业的大多数产品都是多材料结构。材料通过各种连接技术连接，目的是优化生产和操作阶段的性能。然而，在报废阶段的回收过程中，需要将不同材料组合在多材料结构中，例如断开连接并再次分离，以实现高材料回收率。典型的回收方法使用粉碎技术来释放材料。有效的材料释放有助于实现欧盟规定的报废产品的高回收率，从而减少对初级资源开采的需求并实现更可持续的发展。

为了表征材料释放，我们对汽车 A 型车架典型的多材料轻质结构进行了实验性切碎研究，该结构由钢和复合材料组成，在试验旋转剪切机中分两个序列切碎。我们通过一组定量和定性指标来表征饲料和产生的后代颗粒，从而跟踪两个加工步骤过程中接头特性、材料成分和颗粒尺寸的变化。我们发现材料释放取决于许多设计和粉碎参数。我们对饲料和后代颗粒的表征方法允许将设计参数与释放行为联系起来。由于设计和切碎参数的高度可变性，实验数据采集很费力。所以，我们使用有限元方法对基于物理的数值模拟模型的初步结果进行了展望。一旦经过验证，许多设计配置的切碎模拟应告知设计师有关多材料结构（例如 A 型框架试样）的释放行为。