Integrative calculation of the weld strength of plastics parts based on an interdiffusion model presented for laser transmission welding

基于激光透射焊接相互扩散模型的塑料件焊接强度综合计算

基本信息

批准号：
321043881
负责人：
Professor Dr.-Ing. Christian Hopmann
金额：
--
依托单位：
Institut für Kunststoffverarbeitung (IKV) in Industrie und Handwerk an der RWTH Aachen
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/321043881?language=en
关键词：
Integrative calculation weld strength plastics

项目摘要

Independent of the considered welding process the bond strengths is an important characteristic value for the mechanical design of welded parts, because the weld seam often is a weak point and therefore a potential place of failure in a structure. In addition to the mechanical and thermal properties of the welded materials the height of the bond strength is crucially dependent on the welding parameters. Currently the design of the welding zone is found in an iterative process, where both the welding parameters as well as the actual geometry of the welding zone are adjusted following to empirical guidelines. At this time there is no prediction of the resulting bond strengths based on physical models.Therefore in this present project a multi scale simulation for the calculation of the bond strength through the example of laser transmission welding shall be established and validated. The laser transmission welding is an important method for the welding of thermoplastics, so that the established approach can be validated using the laser welding. In addition the transferability of the developed general approach shall be verified. Besides the low heat input into the welded parts the main reason for the use of this process is the high welding speed as well as the high bond strength in the weld. The bond strength in the weld seam is a local size, which is both position-dependent as well as process parameter-dependent. The bond strength in the weld seam can be determined through a simulation of the interdiffusion processes, which take place on a molecular level. This simulation should be based on a reptation model. Therefore a close to reality calculation of the local temperature distribution in the weld seam is necessary. A suitable concept has already been developed by the petitioner, which should be developed further in the course of this research project. This concept can be used to calculate the interdiffusion itself as well as the bond strength distribution in the weld seam caused by the interdiffusion. In addition to the distribution of the bond strength in the weld seam thermal induced residual stresses have a huge impact on the tensile strength of welded parts. Based on the thermally calculations thermo-mechanical simulations for the determination of the residual stress distribution in the weld seam shall be executed. This distribution is dependent on the welding parameters. Through a simulative determination of both the bond strength as well as the residual stress distribution a clearly improved prediction of the structural mechanical behaviour of welded parts is possible.

独立于考虑的焊接过程，键强度是焊接部件的机械设计的重要特征值，因为焊接接缝通常是弱点，因此是结构中的潜在故障位置。除了焊接材料的机械和热性能外，键强度的高度至关重要取决于焊接参数。目前，在迭代过程中发现了焊接区的设计，其中焊接参数以及焊接区的实际几何形状都按照经验指南进行调整。目前尚无基于物理模型的最终键强度的预测。因此，在本项目中，应建立和验证通过激光传输焊接示例计算键强度的多量表模拟。激光传递焊接是热塑性塑料焊接的重要方法，因此可以使用激光焊接验证已建立的方法。另外，应验证开发的一般方法的可传递性。除了低热量输入到焊接部位外，使用此过程的主要原因是高焊接速度以及焊接中的高粘结强度。焊接接缝中的键强度是局部大小，既依赖于位置，又依赖于过程参数。焊缝接缝中的粘结强度可以通过对扩散过程的模拟来确定，该过程发生在分子水平上。该仿真应基于仓库模型。因此，必须接近接近焊接接缝中局部温度分布的现实计算。请愿人已经开发了一个合适的概念，该概念应在该研究项目的过程中进一步开发。该概念可用于计算扩散本身以及由扩散引起的焊缝接缝中的键强度分布。除了在焊接接缝热诱导的残留应力中的键强度的分布对焊接部件的拉伸强度产生了巨大影响。基于热计算，应执行用于测定焊缝中残留应力分布的热机械模拟。该分布取决于焊接参数。通过模拟确定键强度和残余应力分布，可以明显改善对焊接部件的结构机械行为的预测。