Evaluation of robotic fiber placement effect on process‐induced residual stresses using incremental hole‐drilling method

Abstract

The robotic fiber placement (RFP) process depends on continuous fusion bonding and solidifying of prepreg tows onto a substrate by subjecting them to a compression force and heat flux. However the advantages provided when using the RFP to fabricate the composite structures, it has adverse effects due to the induced residual stresses (RSs). The current work presents the effect of the RFP on the induced RSs in thermoset composites. RFP is utilized to fabricate specimens from carbon fiber reinforced polymers. Effects of placement speed, compression force, heating temperature, heating gas flowrate, and the location of the heat flux outlet nozzle are all included in the present study. A total of 69 flat panels are manufactured under different process conditions. Subsequently, the in‐depth RSs are measured using the incremental hole‐drilling method. Besides, the microstructures of the samples are also analyzed. The results show that the change in process parameters could significantly affect the induced RSs of the thermoset composites. Subjecting the samples to higher thermal and pressure loads would induce more RSs, which are attributed to the occurrence of partial curing during the manufacturing process along with the change in laminate geometry and porosity.

On the Role of Damage Evolution in Finite Element Modeling of the Cutting Process and Sensing Residual Stresses

“…The RSs were measured through the incremental hole-drilling method (IHDM). The IHDM was conducted in three stages, as detailed in [ 45 , 46 ]. A tiny hole was drilled in the area of interest, rosetta strain gauges were used to measure the induced strains, and finally the strains were calibrated numerically and the RSs were measured in the cutting direction.…”

Micro drilling characterization of the carbon and carbon–aramid (hybrid) composites

“…10,11 Researchers have extensively studied the drilling of composite materials which have contributed to this area through important experimental investigations on cutting forces, energy consumption, cutting temperature, and damages during the fiber-reinforced composite drilling process. [12][13][14] However, one of the major challenges in manufacturing these composites is the ability to create small and precise holes, known as micro-holes, without compromising the integrity of the material. Also, delamination has been identified as the most significant and recurring defect occurring during the drilling process, based on findings in the existing literature.…”

“…Mechanical drilling and laser drilling methods are common practices for fiber‐reinforced composites and in some cases, combining these techniques allows for optimizing efficiency, balancing cost considerations with the need for precision in composite hole‐making processes 10,11 . Researchers have extensively studied the drilling of composite materials which have contributed to this area through important experimental investigations on cutting forces, energy consumption, cutting temperature, and damages during the fiber‐reinforced composite drilling process 12–14 . However, one of the major challenges in manufacturing these composites is the ability to create small and precise holes, known as micro‐holes, without compromising the integrity of the material.…”

Effect of embedded periodic fiber placement gap defects on the microstructure and bistable behavior of thermoplastic composite laminates

“…23,24 Automated tape laying (ATL) and automated fiber placement (AFP) have been developed to enhance productivity in addition to the size of structures. 25 ATL is capable of laying wide unidirectional prepreg tapes on sample molds, while AFP utilizes a bunch of narrow tows of fiber prepreg material and places them adjacent to each other during the fabrication process. 26 Nevertheless, various defects are unavoidably generated in composite structures as a result of the positional deviation of the programmed path and multiple reasons during the fiber deposition process.…”

“…Conventional hand lay‐up techniques are severely constrained owing to the low productivity and inaccuracies of manual operations 23,24 . Automated tape laying (ATL) and automated fiber placement (AFP) have been developed to enhance productivity in addition to the size of structures 25 . ATL is capable of laying wide unidirectional prepreg tapes on sample molds, while AFP utilizes a bunch of narrow tows of fiber prepreg material and places them adjacent to each other during the fabrication process 26 …”