Modeling of the thermally induced residual stresses during laser transmission welding of thermoplastics
Modeling of the thermally induced residual stresses during laser transmission welding of thermoplastics
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DOI：
10.1007/s40194-019-00770-9
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发表时间：
2019-09
影响因子：
2.1
通讯作者：
C. Hopmann;Simon Bölle;Suveni Kreimeier
中科院分区：
文献类型：
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作者：
C. Hopmann;Simon Bölle;Suveni Kreimeier
激光传输焊接是用于连接热塑性塑料的各种焊接技术之一。激光传输焊接在塑料加工行业中占有一席之地的原因是其对被焊件的低热量引入和高焊接速度。在热塑性塑料的所有焊接过程中，由于加热过程中的热膨胀和随后冷却过程中的热膨胀复位，会产生残余应力。这些热致残余应力损害了焊接构件的力学性能。为了估计残余应力，从而改进工艺设置和对焊接过程的理解，在IKV建立了激光透射焊接的热-力学模拟模型。在一个链接的模拟中，温度分布和机械应力在每个时间步并行计算。该材料是聚酰胺6.6，具有弹性，弹塑性和线性粘弹性行为。冷却后，计算了实际大小的残余应力。然而，由于在焊接过程中超过了聚酰胺的屈服点，因此仅在弹塑性材料模型中才能正确地映射焊接构件中的拉伸/压缩比。
Laser transmission welding is one of the various welding techniques used to join thermoplastics. Low heat introduction into the welded parts and a high welding speed are the reasons why laser transmission welding established itself in the plastic processing industry. In all welding processes for thermoplastics, residual stresses occur due to the thermal expansion during heating and its resetting during subsequent cooling. These thermally induced residual stresses impair the mechanical properties of the welded components. To estimate the residual stresses and therefore to improve the process setup and understanding of the welding process, a thermo-mechanical simulation model for the laser transmission welding is developed at the IKV. In a linked simulation, the temperature distribution and mechanical stresses are calculated parallelly for each time step. The material, a polyamide 6.6, is modeled with elastic, elastoplastic, and linear viscoelastic behavior. After cooling, residual stresses of a realistic magnitude are calculated. However, as the yield point of the polyamide is exceeded in the welding process, the tensile/compression ratio in the welded component is only mapped correctly for the elastic-plastic material model.