Date of Award

5-2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical Engineering

Committee Chair/Advisor

Gang Li

Committee Member

Srikanth Pilla

Committee Member

Oliver J. Myers

Committee Member

Hongseok Choi

Abstract

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.

In the present work, a manufacturing-to-response (MTR) pathway was developed and implemented to establish a relationship between manufacturing process and structural response/properties and optimize manufacturing parameters to achieve optimum response/properties through three separate studies. In the first study, the MTR pathway was implemented for end-to-end analysis of thermoplastic based CFRP composite hat structure manufactured by thermoforming process. This pathway comprised of numerical simulation of manufacturing process and structural performance of CFRP hat structure and their experimental validation from coupon to structural level. The pathway was then used to demonstrate the manufacturing process effects on structural responses/performance through a numerical study. In the second and third studies, the MTR pathway was implemented for manufacturing optimization of thin-ply CFRP structure manufactured by curing process. This was accomplished in three steps: a) First, design selection of an Out-of-Autoclave tool was conducted based on thermal performance, b) Second, manufacturing optimization of the cure process parameters was performed using cure process model and Genetic algorithm (GA) and c) Third, the GA was substituted with statistical method consisting of Bayesian optimization with Gaussian Process model as surrogate to significantly reduce computation time while maintaining prediction accuracy. The objective of the first study was to demonstrate manufacturing process effects and its influence on the structure’s performance. While the second and third studies aimed to optimize the manufacturing process to minimize the process-induced effects and thereby achieve optimum performance/properties.

Author ORCID Identifier

0000-0002-2077-3655

Available for download on Saturday, May 31, 2025

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