Numerical simulation of water jet–guided laser cutting of carbon fiber–reinforced plastics

Abstract

Carbon fiber–reinforced plastics are now widely used in various industries because of its excellent properties. Although milling and drilling are the dominating processing methods for carbon fiber–reinforced plastics at present, laser beam machining, as a wear-free, contactless and flexible process, is considered a promising alternative method. However, the thermal damage is one of the most important issues for laser beam machining of carbon fiber–reinforced plastics because of the significant difference in thermal properties of carbon fiber and matrix. Water jet–guided laser technique has been proved an effective technique to reduce heat damage. Nevertheless, there are few studies about carbon fiber–reinforced plastics processing with water jet–guided laser to date. It is important to understand the mechanism of interaction between water jet–guided laser and carbon fiber–reinforced plastics. Hence, a three-dimensional finite element model was developed to investigate the transient thermal process. The influence of scanning speed on the surface appearance, heat-affected zone and shape of the cross section was illustrated. Experiments with same process parameters were conducted to validate the model. Based on the finite element model and experiments, the mechanism of material removal was explained. The epoxy is considered to be removed once it reaches the melting point and the carbon fiber is removed at the sublimation temperature. Because of the strong cooling effect of water jet, there is nearly no heat accumulation between pulses, leading to the constant heat-affected zone width at different scanning speed. The kerf sidewall is relatively vertical due to the homogeneous power distribution in water jet. The results demonstrate that water jet–guided laser cutting of carbon fiber–reinforced plastics has some advantages than traditional laser beam machining and is a potential processing method for carbon fiber–reinforced plastics.

Towards intelligent CFRP composite machining: Surface analysis methods and statistical data analysis of machined fibre laminate surfaces

“…These surface analysis methods can also be used to compare surface quality of existing cutting removal processes like edge trimming with novel techniques such as water jet guided laser cutting of fibrous composites with a higher degree of accuracy. 32 Subsequent improvements in the methods for surface roughness characterisation applied to the identification of defects and the prediction of surface topography will have impact in future manufacturing practises of CFRP components to improve accuracy, reliability and confidence in surface quality and machining-induced damage detection. This can prevent rework of manufactured aerospace parts and improve the performance of in-service components by the use of more reliable techniques to detect surface defects, like pitting and fibre pull-put.…”

Multi-pass laser cutting of carbon/Kevlar hybrid composite: Prediction of thermal stress, heat-affected zone, and kerf width by thermo-mechanical modeling

“…Material's thermal properties at different temperatures. 4,5,15,16 Temperature (K) Table 2. Material's mechanical properties.…”

“…Therefore, modeling of the laser cutting process and the corresponding temperature distribution and thermal stress field becomes essential. 1 There are limited numerical studies concerning cutting of Kevlar fiber reinforced polymer (KFRP) 2,3 and carbon fiber reinforced polymer (CFRP) [4][5][6] composites using lasers, owing to inhomogeneous thermal properties.…”

“…Similarly, Sun et al. 5 used “element birth and death” technique in single-pass unidirectional CFRP laser cutting with and without the assistance of waterjet. Comparatively, smaller HAZ and shallower ablation depth were observed for the former case.…”

“…Due to limitation of ‘element birth and death’ technique, previously predicted HAZ was confined based on the extent of fiber pullout due to matrix vaporization. 4 , 5 In fact, experimental results show that HAZ consists of two distinguishable regions: (a) vaporized matrix and charred fibers near the cutting kerf, and (b) damage in the neighboring region predominantly in matrix accompanied by minimal fiber pullout. 10 , 11 Using Hashin failure criteria, it is now possible to precisely predict HAZ and kerf width for either singular or hybrid composite.…”