Publication: The Elastic distortion calculation of the piston-cylinder unit of a new dead-weight-tester
Abstract
Bu çalışma bir pistonlu basınç standardıyla ilgili olup, genel olarak, cihazın tasarım ve imalatı, metrolojik özelliklerinin belirlenmesi ve en son olarak ta modellenmesi şeklinde özetlenebilir. Önce test amaçlı bir cihaz tasarlanıp üretildikten sonra karşılıklı dengeleme yöntemiyle test edilmiş, cihaza ait piston-silindir ünitesinin efektif alan değeri ile toplam basınç belirsizliği hesaplanmıştır. Üniteye ait elastik distorsiyon katsayısı basit bir ampirik formül yardımıyla hesaplanmıştır. Sonuçların beklenilen düzeyde çıkması üzerine prototip bir pistonlu basınç standardı tasarımı ve imalatı gerçekleştirilmiş, ve bu cihaza ait piston-silindir ünitesinin efektif alanı hem karşılıklı dengeleme metoduyla, hem de boyutsal ölçümlerden faydalanılarak tespit edilmiştir. Elastik distorsiyon katsayısı hem deneysel olarak, hem de ampirik formül yardımıyla hesaplanmıştır. Daha sonra Solidworks 99 CAD ston-silindir ünitesinin 3 boyutlu bir katı modeli oluşturulduktan sonra piston-silindir boyunca ardışık olarak hesaplanan basınç ve boşluk profilleri hesaplanarak elastik distorsiyon katsayısı hesaplanmıştır. Basınç profilinin hesaplanmasında Mathcad 5.3, boşluk profilinin hesaplanmasında ise Designspace 5 Sonlu Elemanlar kullanılmıştır. Sonuç olarak hesaplanan boşluk profili, basınç profili ile birlikte kullanılarak, elastik distorsiyon katsayısı Mathcad 7 programında hesaplanmıştır. Sonuçlar değerlendirilmiş, ve cihazın karakterizasyonu tamamlanbmıştır. Tüm çalışmalar TÜBİTAK-Ulusal Metroloji Enstitüsü, Basınç ve Vakum Laboratuvarı'nda yapılmıştır.
This study is all about a pressure balance, which can be summarized as the design and manufacture of the device, determination of the metrological properties and finally the modeling procedure. First of all, a test pressure balance was designed and manufactured, and tested by using the cross-float technique, standard pressure metrology. Effective area and the overall pressure uncertainy of the piston-cylinder unit was determined. Elastic distortion coefficient of the device was calculated, using a simple, empirical formula. Owing to the satisfactory results achieved in the test device, a prototype pressure balance was designed and manufactured, and tested by using both cross-float technique and the direct derivation from dimensional metrology. Elastic distortion coefficient was calculated both experimentally and by using the same empirical formula. Then, a 3-D model of the piston-cylinder unit of the pressure balance was created by using the Solidworks 99 CAD Software, and the elastic distortions of the unit were calculated by a series of iteration calculations, to be carried between sequential pressure profile calculations and Finite Element Analysis of the model. MatLab 5.3 Program was used for the determination of the pressure profiles, and Designspace 5 FEA Software was used for the Finite Element Analysis Calculations. The elastic distortion coefficient of the unit was calculated by using the Mathcad program, version 7. The results were evaluated, and the characterization of the device was accomplished. The whole work was done at the Pressure & Vacuum Laboratory of the Ulusal Metroloji Enstitüsü, the national institute of metrology in TURKEY.
This study is all about a pressure balance, which can be summarized as the design and manufacture of the device, determination of the metrological properties and finally the modeling procedure. First of all, a test pressure balance was designed and manufactured, and tested by using the cross-float technique, standard pressure metrology. Effective area and the overall pressure uncertainy of the piston-cylinder unit was determined. Elastic distortion coefficient of the device was calculated, using a simple, empirical formula. Owing to the satisfactory results achieved in the test device, a prototype pressure balance was designed and manufactured, and tested by using both cross-float technique and the direct derivation from dimensional metrology. Elastic distortion coefficient was calculated both experimentally and by using the same empirical formula. Then, a 3-D model of the piston-cylinder unit of the pressure balance was created by using the Solidworks 99 CAD Software, and the elastic distortions of the unit were calculated by a series of iteration calculations, to be carried between sequential pressure profile calculations and Finite Element Analysis of the model. MatLab 5.3 Program was used for the determination of the pressure profiles, and Designspace 5 FEA Software was used for the Finite Element Analysis Calculations. The elastic distortion coefficient of the unit was calculated by using the Mathcad program, version 7. The results were evaluated, and the characterization of the device was accomplished. The whole work was done at the Pressure & Vacuum Laboratory of the Ulusal Metroloji Enstitüsü, the national institute of metrology in TURKEY.