Politeknik Dergisi 2147-9429 Gazi Üniversitesi 10.2339/politeknik.1770895 Material Design and Behaviors Mechanical Engineering (Other) Malzeme Tasarım ve Davranışları Makine Mühendisliği (Diğer) Cockcroft-Latham Hasar Modeli Kullanılarak DP800 İleri Mukavemetli Çelik Delme-Zımbalama İşleminde Yüzey ve Boyut Olayların Değerlendirilmesi Evaluation of Surface and Dimensional Phenomena in Punching of DP800 Advanced Strength Steel Utilising The Cockcroft-Latham Damage Model https://orcid.org/0000-0002-3617-9749 Demir Bilge KARABUK UNIVERSITY https://orcid.org/0000-0001-9746-1580 Seras Samet KARABÜK ÜNİVERSİTESİ https://orcid.org/0000-0001-6189-6830 Gürün Hakan GAZİ ÜNİVERSİTESİ 04 21 2026 29 4 1 9 08 23 2025 11 12 2025 Copyright © 1998, Politeknik Dergisi 1998 Politeknik Dergisi

Bu çalışma, yüksek mukavemet-ağırlık oranı nedeniyle otomotiv bileşenlerinde yaygın olarak kullanılan DP800 gelişmiş yüksek dayanımlı çeliğin (AHSS) delme davranışının nicel ve orijinal bir araştırmasını sunmaktadır. 1,5 mm kalınlığındaki DP800 saclar üzerinde yapılan deneysel testler, düzgün uzama davranışıyla birlikte ~900 MPa'lık maksimum gerçek gerilmeyi ortaya koymuştur. Beş farklı delme geometrisi değerlendirilmiştir; bunlar arasında P16 delme en pürüzsüz kesme yüzeyini ve en düşük çapak yüksekliğini (0,08 mm) üretirken, düz delme 0,11 mm vermiştir. Cockcroft-Latham (C-L) hasar modeli kullanılarak gerçekleştirilen sonlu elemanlar simülasyonları, deneysel sonuçlarla uyumlu olan C = 1,5'lik bir kritik hasar sabitini doğrulamıştır. Kesme bölgesi toplam sac kalınlığının yaklaşık %28'ini oluşturmaktadır ve boyutsal doğruluk ölçümleri, P16 delmenin nominal 20 mm'ye en yakın delik çaplarına ulaştığını göstermiştir. AHSS'nin genel davranışına odaklanan önceki çalışmalardan farklı olarak, bu çalışma DP800 delme mekaniği ve yüzey kalitesinin ayrıntılı bir nicel analizini sunmaktadır. Bulgular, takım geometrisi optimizasyonu ve hasar tahmini konusunda yeni bilgiler sunarak, AHSS şekillendirme operasyonlarında üretim hassasiyetini ve süreç güvenilirliğini artırmak için pratik kılavuzlar sunmaktadır.

This study presents a quantitative and original investigation of the punching behaviour of DP800 advanced high-strength steel (AHSS), widely used in automotive components due to its high strength-to-weight ratio. Experimental tests on 1.5 mm thick DP800 sheets revealed a maximum true stress of ~900 MPa, accompanied by uniform elongation behaviour. Five distinct punch geometries were evaluated, among which the P16 punch produced the smoothest cutting surface and the lowest burr height (0.08 mm), while the flat punch yielded 0.11 mm. Finite element simulations performed using the Cockcroft–Latham (C–L) damage model confirmed a critical damage constant of C = 1.5, which agrees with the experimental results. The shear zone accounted for approximately 28% of the total sheet thickness, and dimensional accuracy measurements indicated that the P16 punch achieved hole diameters closest to the nominal 20 mm. Unlike previous studies that primarily focused on the general behaviour of AHSS, this work provides a detailed quantitative analysis of DP800 punching mechanics and surface quality. The findings deliver novel insights into tool-geometry optimisation and damage prediction, offering practical guidelines for improving manufacturing precision and process reliability in AHSS forming operations.

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