YLD 2000 akma fonksiyonu parametrelerinin belirlenmesinde ardışık kuadratik programlama ve aktif set metotlarının performanslarının incelenmesi

Year 2021, Volume: 10 Issue: 2, 763 - 769, 27.07.2021

Bora Şener

https://doi.org/10.28948/ngumuh.826850

Abstract

Bu çalışmada, Yld2000 akma fonksiyonunun katsayılarının belirlenmesinde nümerik optimizasyon tekniklerinden ardışık kuadratik programlama ve aktif-set metotlarının performansları değerlendirilmiştir. Çalışmada iki alüminyum alaşımı (AA6111-T4, AA6181-T4) ve bir yüksek mukavemetli sac malzeme (DP980) seçilmiştir. Yöntemler, hata fonksiyonunu yakınsama hızlarına ve minimizasyon sırasında inceledikleri fonksiyon sayısına göre değerlendirilmiş olup, üç malzeme için de aktif-set metodunun ardışık kuadratik programlamaya göre daha başarılı olduğu belirlenmiştir. Metodu doğrulamak için, belirlenmiş katsayılara göre malzemelerin akma gerilmesi oranları, Lankford katsayılarının sac düzlemi içerisindeki değişimleri ve akma yüzeylerinin pozitif bölgeleri tahmin edilmiş ve teorik sonuçlar deneysel sonuçlarla karşılaştırılmıştır. Yapılan karşılaştırmalardan malzemelerin düzlemsel anizotropilerinin ve pozitif bölgede akma yüzeylerinin başarılı bir şekilde tahmin edilebildiği görülmüştür.

Keywords

Yld2000, Ardışık kuadratik programlama, Aktif-set metot, Düzlemsel anizotropi, Akma yüzeyleri

Investigation of performances of sequential quadratic programming and active-set methods in the determination of YLD2000 yield function parameters

Abstract

In this study, performances of sequential quadratic programming and active-set methods from numerical optimization techniques were investigated in the determination of Yld2000 yield function coefficients. Two aluminum alloys (AA6111-T4, AA6181-T4) and a high strength steel sheet material (DP980) were selected in the study. Methods were examined according to their convergence rate and the number of function evaluations that occurred during the minimization and it was determined that active-set method was more successful than sequential quadratic programming for three materials. The variations of the yield stress ratios and Lankford coefficients in the sheet plane and positive regions of yield surfaces of the materials were predicted and theoretical results were compared with experimental results to validate the method. It is seen from the comparisons that planar anisotropy and yield surfaces of the materials in the positive regions could be successfully predicted.

Keywords

Yld2000, Sequential quadratic programming, Active-set method, Planar anisotropy, Yield surfaces

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