Ultrasonik kayma dalgaları tomografisi ile beton kusurlarının incelenmesinde frekansın etkisi

Öz

Ultrasonik Kayma Dalgaları Tomografisi (UKDT) yapıdaki nesneleri, ara yüzleri ve anomalileri tespit etmek için ultrasonik kayma dalgaları kullanan modern bir tahribatsız yöntemi olarak önerilmektedir. Bu yöntem sayesinde yapının tamamının hızlı ve ekonomik bir şekilde hiçbir elemana zarar vermeden incelenebilmesine olanak tanınmaktadır. Bu şekilde yapı elemanlarında kayma dalgalarının ultrasonik geçiş özellikleri üç boyutlu olarak görselleştirilebilmektedir. Bu çalışmada betonun UKDT ile incelenmesinde frekansın etkisi üzerine yapılan deneysel çalışma sonucunda elde edilen bulgular sunulmuştur. Deneysel çalışmalarda kullanılan cihazda 24 adet transdüser bulunur ve cihazın çalışma frekans aralığı 25-250 kHz’dir. Deneyler için laboratuvarda 50x50x22 cm boyutlarında üç adet beton numune üretilmiştir. Donatı ve kusurları temsil etmesi amacıyla beton numunelerin içerisine farklı malzemeler yerleştirilmiştir. Her bir numune üzerinde dört farklı frekans değerinde (25-50-100-200 kHz) deneyler yapılmıştır. Deneyler sonucunda her bir frekans değerinde elde edilen tomografik kesitler ile numuneler içerisine yerleştirilen, tip, ebat ve yerleşimleri bilinen donatı ve kusurlar eşleştirilmeye çalışılmıştır. Bu çalışmada elde edilen sonuçlara göre, uygulanan beton malzemelerde UKDT yöntemi ile yapılacak olan deneylerde, aranan kusurun özelliklerine göre, uygulanan frekans değerinin sonucun doğruluğuna etkisinin değiştiği sonucuna varılmıştır. 25 kHz ve 50 kHz frekanslarında yapılan deneylerde numunelerin içerisine yerleştirilen malzeme boyutlarının belirlenmesi gerçeğe yakın doğrulukla yapılabilmekteyken 100 kHz ve 200 kHz değerleri ise sadece numune boyutlarının yani beton elemanın sınırlarının belirlenmesi için yeterli olabilmiştir.

Anahtar Kelimeler

• Ultrasonik kayma dalgası
• Ultrasonik tomografi
• Betondaki kusurlar
• Tahribatsız deney

Effect of frequency on the evaluation of the concrete defects by ultrasonic shear wave tomography

Abstract

Ultrasonic Shear Wave Tomography (USWT) is recommended as a modern non-destructive method that uses ultrasonic shear waves to detect objects, interfaces, and anomalies in the structure. The entire structure can be analyzed quickly and economically without destruction of any structural element. Thus, ultrasonic transition properties can be visualized in three dimensions by means of this method. In this work, results of experimental studies conducted on the effect of frequency on the analysis of the concrete by USWT are explained. The test device used in experimental studies has 24 transducers and its operating frequency range is 25-250 kHz. 50x50x22 cm sized three concrete specimens were produced in the laboratory for the experiments. Different materials were embedded in the concrete specimens to represent reinforcement and defects. Experiments were carried out at four different frequency values (25-50-100-200 kHz) on each specimen. The tomographic crosssections obtained at each frequency value were studied. The reinforcement and defects obtained in tomography sections were tried to match the known properties of placed objects in the concrete specimens. According to the results obtained in this study the accuracy of the results obtained depending on the frequency value varies according to the characteristics of the defect. The materials placed in the specimens tested at 25 kHz and 50 kHz values were determined with high accuracy whereas the values of 100 kHz and 200 kHz were only satisfactory to determine the specimen sizes, in other words, the boundaries of the concrete element.

Keywords

• Ultrasonic shear waves
• Ultrasonic tomography
• Concrete defects
• Nondestructive testing

Kaynakça

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