Akademik Veri Yönetim Sistemi
Tezin Türü: Doktora
Tezin Yürütüldüğü Kurum: Erciyes Üniversitesi, Mühendislik Fakültesi, Makina Mühendisliği, Türkiye
Tezin Onay Tarihi: 2022
Tezin Dili: İngilizce
Öğrenci: KEMAL ARSLAN
Danışman: Recep Güneş
Özet:
This study presents a holistic effort including the production, mechanical characterization, impact tests, and numerical modeling of the layered Al6061/SiC FGM (Functionally Graded Material) plates. It is aimed to develop realistic numerical models for predicting the low- and high-velocity impact response of the FGM plates. Three different material compositions of the FGM plate as the metal-rich, linear, and ceramic-rich are considered representing the mechanical behavior transition from ductile to brittle, respectively. Drop-weight impact test method and a single-stage gas gun are utilized respectively for the low- and high-velocity impact experiments. Numerical modeling of the FGM plates is performed by the explicit finite element code, LS-DYNA®. For the constitutive modeling of the FGM plates, mechanical characterization of the FGM layers is performed using the quasi-static compression and SHPB (Split-Hopkinson Pressure Bar) test methods. An experimental-based layer-wise modeling approach that considers the actual mechanical behavior of the FGM plates by the quasi-static and high strain-rate mechanical characterization is implemented in the numerical models. Different constitutive modeling approaches are presented depending on the compositional gradient of the FGM plates and the loading rate (low- or high-velocity impact). For the metal-rich and linear FGM plates, a rate-independent constitutive modeling approach using Piecewise Linear Plasticity Model is presented in the low-velocity impact analysis, while a rate-dependent constitutive modeling approach utilizing mainly Plasticity with Damage Model is developed in the high-velocity impact analysis. For the high ceramic content layers of the ceramic-rich FGM plate, a concrete damage model, Karagozian & Case (K&C) Concrete Model - Release III, is proposed for both low- and high-velocity impact analysis. The numerical results indicate that the developed numerical models predict the low- and high-velocity impact response of the FGM plates with a good agreement in general. Particularly, the proposed concrete damage-based constitutive modeling approach for the ceramic-rich FGM plate shows an excellent improvement for the numerical results compared to the elastoplastic modeling approach, and the improved model successfully captures the brittle damage modes of the ceramic-rich FGM plate such as cone crack, conoidal fracture, and comminution under the impact loads.