Publication: Ark kaynak işlemi sonucu oluşan kalıntı gerilmelerin deneysel ve sonlu elemanlar simülasyonu ile incelenmesi
Abstract
ARK KAYNAK İŞLEMİ SONUCU OLUŞAN KALINTI GERİLMELERİN DENEYSEL VE SONLU ELEMANLAR SİMÜLASYONU İLE İNCELENMESİ Günümüz sanayinde firmalar rekabet güçlerini arttırabilmek için robot otomasyon sistemlerini uygulamaya koymaktadırlar. Böylece robotik kaynak uygulamaları her geçen gün artan üretim miktarları ve kalite ihtiyacına bağlı olarak gelişmektedir. Kaynak esnasında yüksek ısı girdisi metalin genleşmesine sebebiyet verir ve soğumaya bırakılınca metal büzülmeye çalışır. Bu büzülme sıcaklığı daha az olan bölge tarafından engellenerek, kalıntı gerilmelerin oluşmasına neden olur. Kalıntı gerilmeler parçanın kullanılma esnasında hasar görmesine sebebiyet verebilmektedir. Bu çalışmada, sabitlenmiş aynı malzemeden ve aynı ebatlardaki saclar robotlu kaynak sistemi kullanılarak 4 mm/ sn, 7 mm/ sn ve 10 mm/ sn hızlarında diğer parametreler sabit olacak şekilde kaynatılmıştır. Kaynak esnasında termokupul kullanılarak sıcaklık ölçümü yapılmıştır. Kaynak işlemi sonrasında oda sıcaklığına kadar sacın soğuması beklenmiş ve ısı girdisine bağlı olarak oluşan kalıntı gerilmeler delik delme metodu kullanılarak incelenmiştir. Aynı ark kaynağı için MSC. Marc Mentat 2007 yazılımı kullanılarak simülasyon modellemesi yapılmıştır. Sonlu elemanlar yöntemi ile 3 boyutlu modellemesi yapılan malzemenin üzerinden Von Mises gerilim değerleri, erişilen maksimum sıcaklık ve ısınma hızı incelenmiştir. Deneyler neticesinde, düşük hızda yapılan kaynaklı birleştirme işleminde termokupul ile sıcaklık ölçümü sonucuna göre yüksek sıcaklık değeri elde edilmiştir. Kalıntı gerilme ölçüm deneyinde ise kaynak hızı arttıkça daha düşük gerinim ve kalıntı gerilme değerleri elde edildiği görülmüştür. Deneysel yolla elde edilen değerler ile sonlu elemanlar yöntemiyle elde edilen değerler karşılaştırılmıştır. Sonuçlara göre kaynak hızı arttıkça ısı girdisi azalmaktadır. Kaynaklı birleştirmede ısı girdisi azaldıkça kalıntı gerilmede azalmaktadır.
AN INVESTIGATION OF RESIDUAL STRESS OCCURRING AS A RESULT OF ARC WELDING OPERATION BY EXPERIMENTAL AND FİNİTE ELEMENT SIMULATION METHODS Recent years, firms have been applying robot automation system to increase their power in the competition. So, robotic welding applications have improved depending on amount of production and need for quality that is increasing day by day. During welding, high heat flux causes expansion of metal. And after metal is left for cooling, then it strives to shrink. Since that contraction is obstructed by the area that has less heat, residual stress occurs. Residual stress could cause damage on component during usage. In this study, fixed sheet metal, which are made of same material and at the same dimensions, are welded with speeds of 4 mm/ sn, 7 mm/ sn and 10 mm/ sn by using robotic welding system. During welding process, measurement of heat was done by using thermocouple. After welding process, it is waited for a while for cooling of sheet metal down to room temperature. And residual stress occurred due to heat flux was observed by using hole drilling method. Simulation modelling for the same arc welding was done by Marc Mentat 2007 software. Von Mises stress values, reached maximum temperature and heat speed was observed via material whose 3-dimensional modelling is done by finite element method. As a result of experiment, high temperature values were measured at welded combining operation that was done slower than the measurement results by the help of thermocouple. Depending on that when welding speed increase less stress and residual stress values are obtained in residual stress measurement experiment. Finally, and values gathered by experimental way were compared with values gathered by finite element method. According to results, as welding speed increases, heat flux decreases. At the welded combining as heat flux decreases, residual stress decreases too.
AN INVESTIGATION OF RESIDUAL STRESS OCCURRING AS A RESULT OF ARC WELDING OPERATION BY EXPERIMENTAL AND FİNİTE ELEMENT SIMULATION METHODS Recent years, firms have been applying robot automation system to increase their power in the competition. So, robotic welding applications have improved depending on amount of production and need for quality that is increasing day by day. During welding, high heat flux causes expansion of metal. And after metal is left for cooling, then it strives to shrink. Since that contraction is obstructed by the area that has less heat, residual stress occurs. Residual stress could cause damage on component during usage. In this study, fixed sheet metal, which are made of same material and at the same dimensions, are welded with speeds of 4 mm/ sn, 7 mm/ sn and 10 mm/ sn by using robotic welding system. During welding process, measurement of heat was done by using thermocouple. After welding process, it is waited for a while for cooling of sheet metal down to room temperature. And residual stress occurred due to heat flux was observed by using hole drilling method. Simulation modelling for the same arc welding was done by Marc Mentat 2007 software. Von Mises stress values, reached maximum temperature and heat speed was observed via material whose 3-dimensional modelling is done by finite element method. As a result of experiment, high temperature values were measured at welded combining operation that was done slower than the measurement results by the help of thermocouple. Depending on that when welding speed increase less stress and residual stress values are obtained in residual stress measurement experiment. Finally, and values gathered by experimental way were compared with values gathered by finite element method. According to results, as welding speed increases, heat flux decreases. At the welded combining as heat flux decreases, residual stress decreases too.