PSI - Issue 68

Tuncay Yalçinkaya et al. / Procedia Structural Integrity 68 (2025) 325–331 Yalc¸inkaya et al. / Structural Integrity Procedia 00 (2024) 000–000

330 6

KH

Ayada

Ayada-m

Brozzo

LR

Damage

OH

MC

Freudenthal

RT

CL

Fig. 2: Numerical comparison of flow forming results with 37.5% thickness reduction.

RT, and Freudenthal that fail to predict accurately at lower reduction ratios. Despite predicting failure on the inter nal surface at low reduction ratios, Brozzo, OH, and CL models are included to evaluate their performance at 50% reduction, where most of the part remains below the critical damage limit, except for a thin circumferential region exceeding the critical value (see Erdogan et al. (2023)). All models, except Ayada, predicted damage on both the outer and inner surfaces. Although the Ayada-m and MC models initially indicate damage initiation on the outside during the process, the damage subsequently exceeds the critical value on both the outside and inside surfaces. On the other hand, the damage prediction of the Ayada model is consistent with experimental observations, showing damage on the outer surface of the formed part. Along with the Ayada model, the KH model also demonstrated good performance; however, in the KH model, the damage value slightly exceeded the critical value in a small area on the inner surface. While Ayada ve KH models predict a damage value concentrated around 1.3 on the outer surface, their distributions on the inner surface are di ff erent. Ayada and KH models estimate damage values of 0.8 and 1.13 on the inner surface, respectively. Nevertheless, the Ayada model exhibits a more uniform and conservative damage distribution on the inner surface compared to the KH model. Although not visually included in this study, the Ayada model predicts high damage in a wide region on the inner and outer surfaces at a 70% reduction ratio, as in the experiment, and the ovality of the part is also distorted.

Brozzo

KH

MC

OH

Ayada

Ayada-m

CL

Damage

Fig. 3: Numerical comparison of flow forming results with 50% thickness reduction.