Yüksek mukavemetli yassı çeliklerin şekillendirilmesinin dijital imaj korelasyonu yöntemiyle incelenmesi
Küçük Resim Yok
Tarih
2018
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Karabük Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Dijital İmaj Korelasyon (DİK) yöntemi birçok endüstriyel alanda, bilimsel ve ticari amaçla kullanılan temassız, güçlü ve kullanışlı bir ölçüm tekniğidir. Son yıllarda, özellikle mekanik testler ile beraber, malzeme davranışlarının anlaşılabilmesi için yaygın olarak kullanılmaya başlanmıştır. Bu çalışmada, iki boyutlu (2B) ve üç boyutlu (3B) DİK yönteminin sac malzemelerin mekanik testlerinde kullanılabilirliği ve geleneksel metotlara kıyasla avantajlarının ve dezavantajlarının ortaya konulması hedeflenmiştir. 2B DİK ölçüm yöntemi, oda sıcaklığı ve yüksek sıcaklıkta yapılan tek eksen çekme testine uygulanmıştır. 3B DİK ölçüm yöntemi ise, oda sıcaklığı ve yüksek sıcaklıkta yapılan Erichsen Kap Testi'nde kullanılmıştır. Tek eksen çekme testinde DP980 sac malzeme, Erichsen Kap Testi'nde ise Ck75 ve 22MnB5 sac malzemeler farklı kalınlıklar ve sıcaklıklarda şekillendirilmiştir. Yapılan her iki malzeme mekanik testinde de bütün şekillendirme deneyleri kamera ile kayıt altına alınmış ve kayıt edilen deney videoları birbiri ardı sıralı görüntü dosyalarına bölünerek DİK yazılımında yer değiştirme, uzama ve kalınlık dağılımları ölçülmüştür. Aynı zamanda sac malzemelerin yırtılma anındaki maksimum kuvvetleri bilgisayar ortamına yük hücresi kullanılarak kayıt edilmiştir. Sonuç olarak, tek eksen çekme testinde DP980 sac malzemenin sıcaklık artışına duyarlı olduğu, sıcaklığın artmasıyla çekme dayanımının azaldığı, ekstansometre ölçümü ile DİK ölçümü kıyaslandığında, tam alan uzama ve yer değiştirmenin DİK ile elde edildiği, ekstansometre ölçümünün ortalama değerler verdiği görülmüştür. Ayrıca, çekme numunesi üzerinden seçilen noktalardan, bölgesel uzamanın homojen deformasyondan çok daha fazla olduğu görülmüştür. Erichsen Kap Testi'nde ise sıcaklığın artmasıyla sac malzemenin şekillendirilmesiyle elde edilen kap yüksekliğinin ve Erichsen indeks sayısının arttığı belirlenmiştir. Diğer yandan, sıcaklık artışı ile yırtılma için gerekli olan maksimum kuvvetin azaldığı gözlemlenmiştir. Her iki mekanik test için DİK yönteminin kullanışlı, pratik ve hassas bir yöntem olduğu vurgulanmıştır.
Digital Image Correlation (DIC) technique is a non-contact, powerful, and useful measurement technique which can be applied to many industrial fields for both commercial and scientific purposes. Recently, this technique has been widely used to understand the behavior of materials in the mechanical testing of materials. In this study, it was aimed to clarify the advantages and disadvantages of the 2D and 3D DIC measurement techniques in the mechanical testing of materials over the traditional measurement methods. 2D DIC was implemented to perform an uni-axial tensile test at room temperature and under elevated temperature. 3D DIC was adopted to Erichsen Cupping Test at room temperature and under elevated temperature as well. While DP980 sheet material was chosen for uni-axial tensile test, Ck75 and 22MnB5 steel sheets with various thickness were used for Erichsen Cupping Test. All the mechanical tests were recorded with high resolution digital cameras as video files and recorded video files were divided into the image sequences. Those image sequences were imported to the DIC software and processed in order to calculate displacement, strain, and thickness distributions. In addition, the maximum forces at fracture moment were recorded into the computer environment using load cell. As a result, it was observed that DP980 steel sheet was a temperature sensitivity material and the tensile strength of DP980 was decreased dramatically under the elevated temperature. When the DIC measurement was compared with the traditional extensometer measurement, it was seen that the whole field strain and displacement distributions were achieved with DIC technique and the extensometer measurement was given only average values. Besides, it was determined that local strains of the points that were selected near the fracture line were always higher than the homogenous deformation among to the points. In the Erichsen Cupping Test, it was observed that the cup height during the deformation of the sheet material and Erichsen index value were increased depends on the increasing of the temperature. Additionally, increment of the temperature was lead decreasing of the maximum forces at the fracture moment. Moreover, it was emphasized that DIC measurement technique is a useful, practical and high accuracy method for both material mechanical tests.
Digital Image Correlation (DIC) technique is a non-contact, powerful, and useful measurement technique which can be applied to many industrial fields for both commercial and scientific purposes. Recently, this technique has been widely used to understand the behavior of materials in the mechanical testing of materials. In this study, it was aimed to clarify the advantages and disadvantages of the 2D and 3D DIC measurement techniques in the mechanical testing of materials over the traditional measurement methods. 2D DIC was implemented to perform an uni-axial tensile test at room temperature and under elevated temperature. 3D DIC was adopted to Erichsen Cupping Test at room temperature and under elevated temperature as well. While DP980 sheet material was chosen for uni-axial tensile test, Ck75 and 22MnB5 steel sheets with various thickness were used for Erichsen Cupping Test. All the mechanical tests were recorded with high resolution digital cameras as video files and recorded video files were divided into the image sequences. Those image sequences were imported to the DIC software and processed in order to calculate displacement, strain, and thickness distributions. In addition, the maximum forces at fracture moment were recorded into the computer environment using load cell. As a result, it was observed that DP980 steel sheet was a temperature sensitivity material and the tensile strength of DP980 was decreased dramatically under the elevated temperature. When the DIC measurement was compared with the traditional extensometer measurement, it was seen that the whole field strain and displacement distributions were achieved with DIC technique and the extensometer measurement was given only average values. Besides, it was determined that local strains of the points that were selected near the fracture line were always higher than the homogenous deformation among to the points. In the Erichsen Cupping Test, it was observed that the cup height during the deformation of the sheet material and Erichsen index value were increased depends on the increasing of the temperature. Additionally, increment of the temperature was lead decreasing of the maximum forces at the fracture moment. Moreover, it was emphasized that DIC measurement technique is a useful, practical and high accuracy method for both material mechanical tests.
Açıklama
Fen Bilimleri Enstitüsü, Makine Eğitimi Ana Bilim Dalı
Anahtar Kelimeler
Teknik Eğitim, Technical Education
