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

随着业务量的增加，需要显著降低辐射声功率。亥姆霍兹谐振器(HR)在移动领域用作吸音器，例如以夹层结构的形式使用，即所谓的HR衬垫。这些吸波材料由基层、穿孔面片和中间腔体结构组成。由于它们的物理原理，这种谐振器的减振效果被限制在很窄的频率范围内。因此，它们不能用于宽带噪声的有效衰减。利用蜂窝状的空腔结构和部分柔性的细胞壁，是拓宽和提高这种HR衬垫的吸收特性的一个很有前途的方法。这些墙通过空气中噪声的压力变化而被激发以抑制振动，从而消散声能。由于热塑性塑料薄膜的密度和厚度较低，以及材料的阻尼性较高，因此特别适合于这些柔性细胞壁区域。通过提供一种蜂窝塑料混合结构，该结构不仅包括柔性蜂窝壁，而且还包括耐压抗剪蜂窝壁，从而确保了减振效果和夹层结构在厚度方向上的抗压强度。将热塑性薄膜与部分涂布的单向增强热塑性胶带相结合是一种很有前途的方法。为实现这些结构的技术生产，概念规划的工艺流程不仅包括胶带的应用，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，首次提出了用于新型HR衬里的具有柔性和刚性孔壁区的泡沫塑料混杂结构的施工概念，并从结构力学的角度进行了分析。对于这些结构，工艺链的概念开发将通过技术综合和用于初步设计的各个子工艺的动静分析来进行。为此，选择和表征了用于加固和非加固细胞壁区的合适的材料和半成品。在此基础上，开发和试验了热塑性塑料薄膜上纤维增强带生产和深加工的应用、切割、仿形和折叠技术。最后，从几何和结构-力学的角度对HR衬垫演示进行了评价。生产工艺研究是开发吸声材料塑料混杂结构系列化生产工艺的基础。

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.