金屬玻璃加入孔洞的塑性變形介觀尺度計算模型

Plastic behavior of metallic glass composite controlled by nanopores: A study of mesoscale model

劉芯君(Hsin-Chun Liu)

指導教授 ： 羅友杰

國立交通大學/工學院/奈米科技研究所/碩士(2019年)

摘要

金屬玻璃本身具有良好的破裂韌性、高彈性係數、高降伏強度、軟磁性和耐腐蝕性。由於具有許多商業用途的潛能，故在研究先進結構材料的領域屬於熱門的對象。本研究嘗試控制金屬玻璃內部缺陷來增加金屬玻璃材料強度與延性，避免金屬玻璃內部有剪切軟化(shear softening)產生，而造成材料破壞。利用異質結構使內部造成應變硬化(strain hardening)。本研究架構模型結合有限元素法(Finite Element Method, FEM) 與動力學蒙地卡羅(kinetic Monte Carlo, kMC)方法來探討金屬玻璃加入孔洞的變形行為，利用MATLAB作為主程式控制有限元素軟體Abaqus來近似求解非均勻應變下的應力應變分布，再以動力學蒙地卡羅引入隨機性與特徵應變。在基材內部加入孔洞作為第二相，將其總孔洞面積當作控制變因，探討三種不同幾何條件包括：孔洞的幾何形狀、尺寸、分佈對塑性變形的影響。試圖阻止內部缺陷只朝單一方向傳播，來提升材料機械性質。本研究結果說明，有效控制孔洞的分佈條件最能使shear softening的效應減緩。

關鍵字

金屬玻璃複合材料 ； 應變硬化 ； 剪切軟化 ； 動態蒙地卡羅 ； 有限元素法 ； 模擬方法

並列摘要

Metallic glass (MG) has excellent fracture toughness, elastic coefficient, yield strength, soft magnetism, and corrosion resistance. Due to these properties, MG has been considered possessing many potentials for commercial applications, it belongs to the popular topic about advanced structural material. This research tries to control internal defects to increase material properties (such as strength, ductility), avoiding shear softening to occur to MG, it will cause the damage. The architecture model combines finite element method (FEM) and kinetic Monte Carlo (kMC) to discuss deformed behavior when MG adds nanopores inside. Making MATLAB as main project to control FEM software Abaqus to approximate solution to stress-strain distribution of non-uniform strain and then using kMC induces random property and eigen strain. Nanopores are added inside the matrix regard as the second phase, the volume fraction is considered as control variable and three geometric conditions: the geometry, size, and distribution of the nanopore are considered as independent variables. Using heterostructure to cause strain hardening inside, trying to prevent internal defects from propagating in a single direction to enhance the mechanical properties of the material. The results of this study show that the effectively control the nanopore distribution is the best method to reduce the effect of shear softening.

並列關鍵字

metallic glass matrix composite ； strain hardening ； shear softening ； kinetic Monte Carlo ； finite element method ； simulation method

參考文獻

參考文獻

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