A Manufacturing-To-Response Pathway for Formed Carbon Fiber Reinforced Polymer Composite Structures

Over the past decade, there has been an increased adoption of thermoplastic and thermoset based continuous carbon fiber reinforced polymer (CFRP) composites for structural applications in several industries. Among the different manufacturing methods, thermoforming process for thermoplastic based continuous CFRP’s offer a major advantage in reducing cycle times for large scale productions. Similarly, out-of-autoclave curing process for thermoset based continuous CFRP’s using heated tooling enables production of large composite structures. However, these manufacturing processes can have a significant impact on the structural performance of parts by inducing undesirable effects. These effects include inhomogeneous fiber orientations, thickness variations, and residual stresses in the formed CFRP structures. This necessitates the development of an optimal manufacturing process that minimizes the introduction of the undesirable factors in the structure and thereby achieves the targeted mechanical performance. This can be done by first establishing a relationship between manufacturing process and mechanical performance and successively optimizing it to achieve the desired targets. To this end, a few attempts have been made to connect the design, manufacturing, and structural simulation steps in series, by developing virtual process chains (CAE chains) and mapping methods. However, the recent publications implementing these methods are missing some of the relevant effects or steps of the manufacturing process. The present work establishes two Manufacturing-to-Response (MTR) pathways for end-to-end analysis of CFRP composite structures. The current study focuses on establishing a relationship between manufacturing process and mechanical performance. As case studies, the MTR pathway was implemented for 1. thermoplastic based Composite Hat structure manufactured by thermoforming process and 2. thermoset based Composite Boom structure manufactured by Out-of-Autoclave (OOA) molding process using self-heated tool. The pathway primarily comprised of material characterization, finite element simulations and experimental validation. The first case study details the MTR pathway for thermoforming process of Composite Hat structure. Thermoforming process effects were studied and incorporated in structural analysis. The second case study details a framework of the MTR pathway for OOA molding of Composite Boom structure. The first two steps of the pathway namely Composite boom tool design and curing analysis were accomplished as a part of the present study. The MTR pathway(s) were validated experimentally for the Composite Hat structure and validation for the Composite Boom structure is planned for future work. Both studies indicated the significance of incorporating the manufacturing process effects into the structural performance of a composite structure

Thermoforming process effects on structural performance of carbon fiber reinforced thermoplastic composite parts through a manufacturing to response pathway

Thermoforming process of thermoplastic-based continuous CFRP\u27s offer a major advantage in reducing cycle times for large-scale productions, but it can also have a significant impact on the structural performance of the parts by inducing undesirable effects. This necessitates the development of an optimal manufacturing process that minimizes the introduction of undesirable factors in the structure and thereby achieves the targeted mechanical performance. This can be done by first establishing a relationship between the manufacturing process and mechanical performance and successively optimizing it to achieve the desired targets. The current study focuses on the former part, where a manufacturing-to-response (MTR) pathway is established for a continuous fiber-reinforced thermoplastic composite hat structure. The MTR pathway incorporates the thermoforming process-induced effects while determining the mechanical performance and principally comprises of material characterization, finite element simulations, and experimental validation. The composite material system selected for this study is AS4/Nylon-6 (PA6) with a woven layup. At first, the thermoforming simulations are performed above the melt temperature of PA6 using an anisotropic hyperelastic material model, and the process-induced effects such as thickness variation, fiber orientations, and residual stresses are captured from the analysis. Residual stresses developed in the formed structure during quench cooling from the elevated temperature are predicted by the implementation of classical laminate theory (CLT). These results are then mapped onto a duplicate part meshed suitably for mechanical performance analysis. A quasi-static 3-point bend test and a dynamic impact test are carried out and the results are compared with experimental tests. Experimental results from thermoforming, bending and dynamic impact trials show good agreement with the simulation results for the hat structure under consideration. Further, the static and dynamic performance is evaluated for the thermoformed structure and the effects of the thermoforming process are compared numerically, for the cases with and without the inclusion of process effects