Development and validation of a method to determine the frequency- and temperature-dependent stiffness and damping properties of plastics for the structure-borne noise simulation more precisely using the example of the for the ultrasonic welding process r

自20世纪60年代以来，超声波焊接在工业上已经确立。到目前为止，连接部件的设计通常基于用户体验。除了连接部件体的几何设计必须适合焊接外，适当的部件结构还需要考虑构造细节，例如连接区域几何形状的工艺特定设计。附加的功能元件或肋结构，它们直接影响结构传递的声音过程，从而影响焊接过程，通常也要考虑在内。一般来说，在开始生产之前，广泛的实际试验是必要的。组件的开发还需要大量的实际试验来确定焊接参数。在许多情况下，为了获得高质量的焊缝，需要对注射成型工具进行反复的精心设计和高成本的重新设计，以影响声音的传播。由于超声焊接的高频率，塑料的动刚度和阻尼特性的材料分析具有挑战性，并且只能通过迭代方法进行。对声结构相互作用的真实模拟有助于探测和避免关键区域。然而，输入数据是必需的，它精确地反映热塑性塑料的粘弹性材料的行为。该研究项目的目的是进一步发展一种基于逆向工程过程的替代方法。这是为了确定一种非晶塑料（PMMA）和两种半晶塑料（PP和PA）的机械特性值，这允许在考虑热影响的情况下，对超声波焊接过程中连接部件的复杂结构声过程进行模型描述。研究结果表明，在设计阶段就可以进行适当的连接部件设计。因此，在复杂连接部件的开发阶段，时间和成本密集的迭代将被省略。此外，将为更好地理解高动态超声焊接过程和声音传播的材料和工艺提供全面的基础。

The ultrasonic welding has been established in the industry since the 1960s. Up to now, the design of the joining parts is usually based on the user experience. As well as the geometric design of the joining part bodies, which has to be suitable for welding, an appropriate component construction requires the consideration of constructive details, such as a process-specific design of the joining zone geometry. Additional functional elements or rib structures, which directly affect the structure-borne sound processes and thus the welding process, are often also to be taken into account. In general, extensive practical trials are necessary before the start of production.The component development also requires extensive practical trials for the determination of the welding parameters. In many cases, iterative elaborate and cost-intensive redesigns of the injection moulding tools arise to influence the sound propagation, so that a high-quality weld seam is achieved. The material analysis of the dynamic stiffness and damping behaviour of plastics is challenging due to the high frequencies of ultrasonic welding, and can only be carried out by means of iterative approaches. Realistic simulation of the acoustic structure interactions can be contributed to detect and avoid critical areas. However, input data are required, which precisely reflect the viscoelastic material behaviour of thermoplastic plastics.The aim of the research project is a further development of an alternative method, which is based on a reverse engineering process. This is supposed to determine mechanical characteristic values for an amorphous plastic (PMMA) and two semi-crystalline plastics (PP and PA), which allow a model description of the complex structure-borne sound processes in joining parts for the ultrasonic welding process, taking into account thermal influences.With the help of the research results, it is to be shown that the appropriate joining part design can already take place in the design phase. As a result, time and cost-intensive iterations in the development phase of complex joining parts will be omitted. Furthermore, a comprehensive basis for a better material and process understanding of the highly dynamic ultrasonic welding process and the sound propagation will be created.