Development of construction methods and synthesis of manufacturing technologies for the production of cellular plastic hybrid structures for applications in sound absorbers

随着交通量的增加，需要显著降低辐射声功率。亥姆霍兹共振器（HR）在移动领域中用作吸声器，例如以夹层结构的形式，所谓的HR衬垫。这些吸收器由基层、穿孔面板和中间腔结构组成。由于它们的物理原理，这种谐振器的阻尼效果限于窄的频率范围。因此，它们不能用于宽带噪声的有效衰减。一个有前途的方法来扩大和增加这种HR内衬的吸收特性是使用蜂窝状腔结构与部分柔性单元壁。这些壁被空气传播噪声的压力变化激励以阻尼振动，从而耗散声能。由于其低密度和厚度以及高材料阻尼，热塑性塑料膜特别适合于这些柔性单元壁区域。通过提供不仅包含柔性单元壁而且包含耐压和抗剪单元壁的泡沫塑料混合结构，确保了阻尼效果和夹层结构在厚度方向上的压缩强度。热塑性薄膜与部分应用的单向增强热塑性胶带的组合代表了一种有前途的方法。这些结构的技术生产实现的概念规划的工艺线不仅包括胶带应用，还包括部分切割，轮廓和折叠的工艺步骤。在本研究项目的范围内，首次开发了新型HR内衬的柔性和刚性单元壁区域的泡沫塑料混合结构的施工概念，并在结构力学方面进行了分析。对于这些结构，工艺链的概念开发将通过技术综合和初步设计的各个子工艺的动态静力分析来进行。为此，选择并表征用于增强和未增强单元壁区域的合适材料和半成品。在此基础上，开发并测试了用于在热塑性薄膜上生产和进一步加工纤维增强胶带的应用、切割、成型和折叠技术。最后，从几何和结构力学的角度对HR内衬演示器进行了评估。生产技术研究是开发用于吸声器的塑料混合结构的系列生产工艺的基础。

As the volume of traffic increases, there is a demand for a significant reduction of the radiated sound power. Helmholtz resonators (HR) are used as sound absorber in the mobility sector, for example in the form of sandwich constructions, so-called HR liners. These absorbers consist of a base layer, a perforated face sheet and an intermediate cavity structure. Due to their physical principles, the damping effect of such resonators is limited to a narrow frequency range. Therefore, they cannot be used for efficient attenuation of broadband noise. A promising approach to widening and increasing the absorption characteristics of such HR liners is the use of honeycomb-like cavity structures with partially flexible cell walls. These walls are excited to damped vibrations by pressure changes of the airborne noise and thus dissipate acoustic energy. Due to their low density and thickness as well as their high material damping, thermoplastic plastic films are particularly suitable for these flexible cell wall areas. By providing a cellular plastic hybrid structure, which contains not only flexible cell walls but also pressure and shear resistant cell walls, the damping effect and the sandwich structure’s compressive strength in the thickness direction are ensured. The combination of thermoplastic films with partially applied, unidirectionally reinforced, thermoplastic tapes represents a promising approach. The conceptually planned process line for the technical production realization of these structures includes not only the tape application but also the process steps of partial cutting, contouring and folding.Within the scope of this research project, construction concepts for cellular plastic hybrid structures with flexible and rigid cell wall areas for novel HR liners are being developed for the first time and analysed in terms of structural mechanics. For these structures, the conceptual development of a process chain is to be carried out by technology synthesis and the kinetostatic analyses of the individual sub-processes for preliminary design. For this purpose, suitable materials and semi-finished products for the reinforced and unreinforced cell wall areas are selected and characterized. Based on this, application, cutting, profiling and folding technologies for the production and further processing of fiber-reinforced tapes on thermoplastic films are developed and tested. Finally, the HR liner demonstrators are evaluated from a geometric and structural-mechanical point of view. The production technology investigations are the basis for the development of a serial production process of plastic hybrid structures for use in sound absorbers.