Spatially Dependent Statistical Modeling of Geometric Variations in Additively Manufactured Lattice Structures

Öz

The content of this study is the modeling of the geometric variations introduced by the material extrusion method on the strut members of lattice structures using advanced statistical methods based on the spatial dependency and investigating their inclusion to the simulation models. For this purpose, strut member specimens with different diameter values are fabricated using the material extrusion technique. The specimens are examined by a digital light microscope and the measurements are done for the fabricated diameter variations. These variations are characterized using the random field method which is commonly used for modeling the spatially dependent variations. These variations modeled by the random field method are integrated into the finite element models by using voxel elements. The results of the finite element analysis that includes the fabricated specimen models with spatial variations are compared with the tensile test results obtained for the fabricated strut specimens. The developed model can be extended to different additive manufacturing techniques and the variations observed in the fabricated geometry and material properties can be characterized.

Anahtar Kelimeler

• Additive Manufacturing
• Material Extrusion
• Lattice Structure
• Finite Element Method
• Random Field.

Eklemeli İmalat ile Üretilen Latis Yapılardaki Geometrik Değişimlerin Konuma Bağlı İstatistiksel Modellenmesi

Öz

Bu çalışmanın temel içeriği, latis yapıların temel bileşenleri olan çubuk elemanların üzerinde, bir eklemeli imalat tekniği olan malzeme ekstrüzyonu yöntemi kullanılarak üretimi sürecinde meydana gelen geometrik değişimleri, gelişmiş istatistiksel yöntemler kullanarak konuma bağlı olarak modellenmesi ve simülasyon modellerine dahil edilebilirliğinin incelenmesidir. Bu amaçla, çubuk eleman numuneleri farklı çap değerlerinde malzeme ekstrüzyonu yöntemi ile üretilmiştir. Üretilen numuneler dijital kameralı ışık mikroskobu altında incelenmiş ve üretim sonrasında gözlemlenen çapta oluşan değişimlerin ölçümleri yapılarak deneysel veriler elde edilmiştir. Söz konusu değişimler, belirli bir uzay içerisinde konuma bağlı değişimlerin modellenmesinde sıkça kullanılan rassal alan (random field) yöntemi kullanılarak modellenmiştir. Rassal alan yöntemiyle modellenen değişimler, voksel elemanlar kullanılarak sonlu elemanlar modellerine dahil edilmiştir. Malzeme ekstrüzyonu yöntemi ile üretilen çubuk elemanların tek eksenli çekme testleri yapılarak, değişimleri içeren, üretilene benzer sonlu elemanlar modellerinin analizlerinden elde edilen sonuçların doğrulu incelenmiştir. Geliştirilen bu yöntem farklı eklemeli imalat yöntemlerine genişletilebilir, üretim sürecinde geometri özellikleri ve malzeme özelliklerinde gözlemlenen değişimler karakterize edilebilir.

Anahtar Kelimeler

• Eklemeli imalat
• Malzeme ekstrüzyonu
• Latis yapı
• Sonlu elemanlar analizi
• Rassal alan

Kaynakça

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