Multifidelity Thermochemical–Mechanical Modeling of Pultruded Hollow Composite Profiles

ABSTRACT Pultrusion of hollow composite profiles with fast‐curing polyurethane (PU) resin requires simultaneous control of heat transfer, cure kinetics, viscosity evolution, and pulling resistance, making empirical process optimization costly and uncertain. This work develops a multifidelity thermo–chemical–mechanical modeling framework for hollow glass‐fiber (GF) and carbon‐fiber (CF)‐reinforced PU profiles produced on an industrial PulFlex pultrusion line. Three complementary model tiers are integrated using a common physics backbone: a one‐dimensional (1D) mathematical model for rapid parametric screening, a two‐dimensional (2D) homogeneous finite element model in ABAQUS for process‐scale response, and a three‐dimensional (3D) laminate‐resolved finite element model in ANSYS for fiber‐architecture and through‐thickness gradient prediction. All models employ Kamal–Sourour cure kinetics, Di Benedetto vitrification, cure‐dependent rheology, and cure‐hardening instantaneously linear elastic modulus evolution to predict temperature, degree of cure, viscosity, glass‐transition temperature, and pulling force along a multizone heated die. Embedded thermocouple measurements are used to calibrate the 1D thermal history and to independently evaluate the 2D and 3D thermal predictions at the reference condition, whereas differential scanning calorimetry‐derived degree‐of‐cure data provide an independent check on cure progression for all three model tiers. The models reveal distinct thermochemical behavior between GF and CF systems and quantify the accuracy‐versus‐cost tradeoff across fidelities. Under the tested three‐zone heater configuration, the multifidelity comparison identifies the speed range over which die‐exit cure, vitrification location, and predicted pulling resistance remain favorable for stable hollow‐profile manufacturing. The calibrated 1D model supports efficient process screening and future digital‐twin integration.