Laser-assisted Tape Winding Process Research Articles

Optimization of thermal model and prediction of crystallinity during the laser-assisted tape winding process

Laser-assisted tape placement and tape winding represent the most advanced automated manufacturing technologies for thermoplastic composites. It is important to accurately predict the complete thermal history of the manufacturing process, on which many properties of the product are strongly dependent, such as interlaminar bonding strength and crystallization. In this article, a nonlinear two-dimensional transient heat transfer model was established in ANSYS APDL, and a new temperature closed-loop controlled near-infrared laser heat source was described. Most importantly, the thermal contact pairs were introduced following the activation of elements, and the value of interlaminar thermal contact resistance was obtained by fitting an independent experiment and finite element analysis, which greatly optimized the heat transfer process in the direction of thickness. The thermal model was verified by infrared cameras and an online temperature measuring system based on thermocouples. The results of thermal history are in good agreement with the experiment, which were input into the crystallization kinetics model to predict the evolution and distribution of crystallinity in the laser-assisted tape winding process. The calculated results are coincident with the differential scanning calorimeter test very well, and the crystallinity was about 17% higher than that before manufacturing.

Optimization of the laser-assisted tape winding process using an inverse kinematic-optical-thermal model

A new inverse kinematic-optical-thermal (IKOT) model is introduced to control the process temperature in laser assisted tape winding and placement processes. The optimum time-dependent laser power distribution is obtained by employing a grid of independent laser cells while keeping the temperature of substrate and tape at the target temperature. Multi-layer cylindrical hoop winding with laser grids of 1 × 1, 28 × 1, and 28 × 11 and helical winding of a pressure vessel with laser grids of 22 × 1 and 22 × 11 are considered. It is found that the optimized laser power distribution pattern remains the same during the consecutive hoop winding process while the total power reduces to compensate the heat accumulation. A more non-uniform laser power distribution is obtained for the helical winding because the substrate curvature changes drastically at the dome section of the pressure vessel. The change in the optimum total laser power is found to be almost constant for the helical winding case. Finally, the IKOT model is evaluated by analyzing the effect of the computational parameters on the optimized process temperature.

Non-uniform crystallinity and temperature distribution during adjacent laser-assisted tape winding process of carbon/PA12 pipes

The non-uniform temperature and crystallinity distributions present in carbon fiber–reinforced PA12 composite pipes, produced via laser-assisted tape winding (LATW), are investigated in this paper. The width of the laser source is usually larger than the substrate width which causes multiple heating and cooling of some regions of the (neighboring) substrate and hence temperature and crystallinity gradients during the adjacent hoop winding. A kinematic-optical-thermal (KOT) model coupled with a non-isothermal crystallinity model is developed to capture the transient temperature and crystallinity distributions for growing substrate thickness and width. The predicted temperature trends are validated with thermocouple and thermal camera measurements. The substrate temperature varies in the width direction up to 52%. This will lead to extra polymer remelting and possible degradation. The maximum variation of the crystallinity degree across the width is found to be 270% which shows agreement with the trend of the measured crystallinity degree. It is found that a more realistic description of the melting behavior of the matrix is needed to obtain a more accurate prediction of the crystallinity distribution.

A fully coupled local and global optical-thermal model for continuous adjacent laser-assisted tape winding process of type-IV pressure vessels

A numerical process simulation framework is introduced in this paper to describe and predict the process temperature evolution during the laser-assisted tape winding (LATW) process of a type-IV pressure vessel made of glass-reinforced high-density polyethylene (G/HDPE). A local optical-thermal model is fully coupled with a global thermal model for the simulation of continuous adjacent hoop winding cases. The predicted tape and substrate temperatures are compared with the experimental data to validate the process model’s effectiveness. The inline temperature was measured by an infrared thermographic camera during the continuous winding. The continuous process temperature of the substrate is affected significantly due to the previously wound layers including the pressure vessel, and a gradual increase of the temperature of the roller and the air inside the liner. A considerable temperature increase calculated as 80-120°C takes place for the substrate during winding of two consecutive layers of (G/HDPE) prepreg tape at the liner ends. The influence of pressure vessel size on the tape and substrate temperatures is investigated for different liner radii using the validated process model. The peak substrate temperature is found to increase approximately 45°C by reducing the radius of the pressure vessel from 272 mm to 68 mm while maintaining all other process conditions constant.

On the temperature evolution during continuous laser-assisted tape winding of multiple C/PEEK layers: The effect of roller deformation

Laser-assisted tape winding (LATW) is a highly automated process for manufacturing tubular-like fiber-reinforced thermoplastic composites such as flywheels and pipes. One of the crucial parameters in the LATW process is the temperature of the nip point at which the incoming prepreg tape is bonded with the substrate by a compaction roller. Therefore, the temperature evolution of the nip point plays a significant role to have a proper consolidation at the tape-substrate interface. The nip point temperature is highly affected by the time-dependent geometry of the substrate and roller during continuous LATW of thick composite rings. In this paper, a critical assessment of the substrate and tape surface temperature evolution is investigated experimentally by means of a thermal camera during the LATW process of a 26-layers thick carbon/PEEK composites. A three-dimensional (3D) optical model is coupled with a thermal model in which the substrate computational domain is updated with respect to the deposited tapes. A good agreement is found between the measured and predicted tape and substrate temperatures. The total absorbed heat and heated length of the substrate and tape are described based on the roller deformation. An increase in tape and substrate nip point temperatures is found with an increase in roller deformation during consecutive winding. It is also found that the consolidation pressure and contact length at the roller-substrate interface increases during the winding process. Accordingly, the heat transfer coefficient at the roller-substrate interface is studied using the developed process model.

3D Numerical Modeling of Laser Assisted Tape Winding Process of Composite Pressure Vessels and Pipes-Effect of Winding Angle, Mandrel Curvature and Tape Width.

Advanced thermoplastic composites manufacturing using laser assisted tape placement or winding (LATP/LATW) is a challenging task as monitoring and predicting nip point (bonding) temperature are difficult especially on curved surfaces. A comprehensive numerical analysis of the heat flux and temperature distribution near the nip point is carried out in this paper for helical winding of fiber reinforced thermoplastic tapes on a cylindrically shaped mandrel. An optical ray-tracing technique is coupled with a numerical heat transfer model in the process simulation tool. The developed optical-thermal model predictions were compared with experimental data available in literature to validate its effectiveness. The influences of winding/placement angle, mandrel curvature and tape width on the incident angles, the laser absorbed intensity, and the process temperature distribution are studied extensively using the validated model. Winding/placement angle has a considerable effect on the temperature distribution. Increase in winding angle results in a higher temperature for tape due to more reflections coming from the substrate. On the other hand, substrate temperature decreases as the winding angle increases due to a decrease in the laser incident angles based on the local surface curvature. An increase in mandrel curvature results in higher nip point temperatures for substrate and lower one for tape. Different mandrel sizes for 90 placement path do not have a strong effect on the substrate process temperature as for other winding angles because of less curvature change of the corresponding irradiated area. Tape width causes local temperature variations at the edges of the tape/substrate. In order to obtain the desired process temeprature during LATW or LATP processes, the laser intensity distribution on the tape and substrate surfaces should be regulated.

Temperature analysis for the laser-assisted tape winding process of multi-layered composite pipes

Tubular structures of fiber-reinforced polymer composites are utilized in various applications such as risers in the oil and gas industry and hydrogen pressure vessels in the automotive sector. The laser-assisted tape winding process presents an automated and efficient solution for the manufacturing of these structures out of thermoplastic composites. However, in order to guarantee reliable and high-quality process results, the temperature distribution within the laminate governing the consolidation between successively wound layers has to be understood and taken into account for process design. In an experimental setup, thermocouples were embedded between the layers in multiple spots along the perimeter during the manufacturing of pipe samples with five layers wound on a pure thermoplastic liner. This enabled capturing the through-thickness temperature distribution at different transversal locations. In addition to the temperature data recorded by the thermocouples, a stationary infrared thermographic camera focused on the laser-heated area was mounted on the tape winding head. The temperature data points of both sources were contrasted to evaluate how the through-thickness temperature distribution reflects the temperature input on the surface. Furthermore, the experimentally determined temperature distribution was compared with the results of a numerical process model, drawing conclusions with regard to the modelling and control of the multi-variable process.

New analytical and numerical optical model for the laser assisted tape winding process

New analytical and numerical optical models are proposed for the laser assisted tape winding (LATW) of thermoplastic composites. The irradiation and reflection of the laser beam directly influence the heat flux and temperature distribution during the consolidation, hence the laser optics must be described and understood well for improved bonding quality. For the first time, a two-dimensional (2D) analytical solution is derived for the laser light distribution and reflection by combining the principle of energy conversation with unpolarized Fresnel equations. In the more comprehensive numerical model, a 3D ray tracing approach is incorporated in which a novel non-specular reflection model is developed predicting the anisotropic reflective behaviour of the composite. Heat flux distributions for the substrate and incoming tape are calculated. The analytical and numerical model results are shown to correspond. The non-specular and scattering reflection yields in a larger illuminated area with lower intensity for substrate and tape.