In-situ manufacturing of thermoplastic composites using Hot Gas Torch (HGT)-assisted Automated Fiber Placement (AFP)  has the potential to produce laminates in  an efficient manner by avoiding a secondary process, like autoclave consolidation. 
One of the advantages of HGT-assisted AFP technique is its capability to steer fiber path and to manufacture Variable Angle Tow (VAT) laminates which have shown to have improved mechanical performance. 
This study investigates the process parameters that affect steering of carbon fiber reinforced thermoplastic tapes (AS4/polyether ether ketone (PEEK)) using a HGT-assisted AFP machine. 
The effect of the steering radius, laydown speed, number of repasses and substrate angle on the geometry and bond strength of steered tape was investigated through observation and testing.  
Through geometrical analysis, it was found that with a decrease in the steering radius of the tape there was a decrease in the tape width and an increase in the tape thickness. 
A significant reduction in the steering induced defects was observed at higher laydown speeds where the defects were intermittent unlike in the case of lower laydown speeds. 
Performing a repass over the steered tape smoothed some of the tape defects caused by steering. 
Currently there is no standard method for testing the bond strength of the steered in-situ consolidated composite tapes with its substrate. 
Hence, a novel mechanical test, inspired by the lap shear test, was devised and used to study the bond strength between the steered tape and the substrate and the results were compared with autoclave treated samples which served as a reference.
Furthermore, the bond strengths of the steered tapes were found to be functions of the laydown speed and substrate angle.

This work also analytically predicts the onset of fiber buckling in the steered tapes to serve as a first approximation or a rule of thumb to understand from which radius fiber buckling can be expected.
Timoshenko's Bar on an elastic foundation forms the basis for the analytical model, where the bar represents the fiber and the elastic foundation the matrix.
Various models that were derived from this idea were studied, and the analytical models that were similar to current problem of fiber buckling were adopted.
These analytical models considered a plane stress approach to model the fiber buckling observed during the bending of Elastic Memory Composites (EMC).
The steering a of CF/PEEK tape using a HGT-assisted AFP is essentially the bending of a plane (the tape) by external moments, which causes the fibers along the inner-edge of the tape to buckle under compression.
The analytical prediction of the critical steering radius showed a good correlation with the experimental observations.