Abstract A method of applying ultrasonic welding to repair adhesive-bonded 2.3 mm thick injection molded short carbon fiber reinforced Nylon 6 (Cf/PA6) composite with 30 wt% fiber was developed. The method included positioning the ultrasonic horn and anvil proximate the region on the workpieces having the partially adhesive-bonds and applying an ultrasonic oscillation at the workpieces where insufficient adhesive was dispensed at the faying surfaces. The effects of horn force, oscillation time, and inadequate adhesive on the quasi-static strengths of the nominal, partially adhesive-bonded and repaired joints were investigated. It was found out that the strengths of the partially adhesive-bonded joints with 0%, 25%,50% and 75% adhesive coverages were restored and achieved over 90% of the nominal joint strength (i.e., full adhesive coverage). Microstructure analyses of the repaired joints demonstrated that the second ultrasonic pulse produced viscoelastic heating and frictional heating, and consequently fused carbon fiber composites at the faying surfaces of the workpieces. The strengths of the repaired (i.e., weld-bonded) lap-shear joints were primarily from the combined contribution of adhesive-bond and ultrasonic weld at the faying surfaces, which were virtually unchanged regardless the amount of adhesive missing. Therefore, for the substrate and joint configuration and dimensions studied here, application of ultrasonic welding virtually restored the quasi-static strengths of partially adhesive-bonded lap-shear Cf/PA6 composites with 30 wt% fiber. Consequently, by the application of this repair method the scrap of the component assembly would be reduced.

中文翻译：

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超声波焊接修复短碳纤维增强尼龙6复合材料的应用

摘要 开发了一种应用超声波焊接修复 2.3 mm 厚注射成型短碳纤维增强尼龙 6 (Cf/PA6) 复合材料的方法，其中含有 30 wt% 的纤维。该方法包括将超声波变幅杆和砧座定位在工件上具有部分粘合剂结合的区域附近，并且在接合表面处分配的粘合剂不足的工件处施加超声波振荡。研究了喇叭力、振荡时间和粘合剂不足对标称、部分粘合剂粘合和修复接头的准静态强度的影响。发现具有0%、25%、50%和75%粘合剂覆盖率的部分粘合剂粘合接头的强度得到恢复并达到标称接头强度的90%以上（即完全粘合剂覆盖）。修复接头的微观结构分析表明，第二次超声波脉冲产生粘弹性加热和摩擦加热，从而在工件的接合表面融合碳纤维复合材料。修复后（即焊接粘合）搭接剪切接头的强度主要来自接合面处的粘合粘合和超声波焊接的综合作用，无论粘合剂缺失的量如何，这些强度几乎都没有变化。因此，对于此处研究的基材和接头配置和尺寸，超声波焊接的应用实际上恢复了具有 30 wt% 纤维的部分粘合剂粘合搭接剪切 Cf/PA6 复合材料的准静态强度。因此，通过应用这种修复方法，将减少部件组件的报废。