Ductile failure analysis during backward flow forming processes

Date

2024-8-05

Author

Vural, Hande

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Flow forming, also known as tube spinning, is an advanced metal forming process that produces thin-walled, high-precision cylindrical components. This process involves incrementally thinning the material using specially designed rollers and a mandrel, ensuring high dimensional accuracy and structural integrity. Due to the complex stress states and significant plastic deformation, accurate forming limit predictions are crucial to optimize the manufacturing process and avoid defects. This study aims to predict forming limits and fracture locations and assess the effects of process parameters on fracture in the flow forming process, focusing on IN718 and Al2024-O materials. The plastic behavior of these materials is modeled using von Mises and Bai-Wierzbicki yield functions with various hardening rules. The study evaluates single and multi-parameter uncoupled damage models in predicting fracture locations and formability limits, calibrated through tensile tests on specimens with different stress-state values. Tensile tests and flow forming processes are modeled with adiabatic heating and displacement-temperature coupled finite element simulations using ABAQUS/Explicit software, respectively. Subroutines such as VUHARD, VUMAT, and VUSDFLD are used to implement the models. The accuracy of each model is assessed by comparing flow forming simulations with experimental trials at various thickness reduction ratios. Critical process parameters like feed rate, revolution speed, reduction ratio, and axial-radial offset are examined to evaluate their effects on failure. By combining experimental data with extensive numerical simulations, this research enhances the accurate prediction of ductile fracture in flow forming, potentially improving manufacturing practices in the automotive, aerospace, and defense industries.

Subject Keywords

Ductile fracture, Flow forming process, Inconel 718, Al2024-O, Finite element method

URI

https://hdl.handle.net/11511/110925

Collections

Graduate School of Natural and Applied Sciences, Thesis