• 作者： 余祥雲
• 作者服務機構： 中正理工學院物理系
• 中文摘要： 本文為計算因等軸橢圓體夾雜物存在所導致的應力場分佈情形以瞭解夾雜物對材質延性破壞的影響。其假設為（一）基質及夾雜物均為等方性理想彈塑性體，而夾雜物不產生塑性變性。（二）基質的變形是均勻的，且變形過程中無塑性鬆弛現象。 所得結果為（一）除夾雜物本身破裂外，孔穴均成核於基質夾雜物之界面。此一孔穴成核所需的塑性變形隨著夾雜物長軸愈靠近張力軸而減少。這一角度變化關係為夾雜物愈硬時愈顯者。而軸相交角度固定時夾雜物硬度增加或形狀變扁時材質延性均降低。（二）夾雜物中的最大主應力是為張力，其大小隨其硬度增加或長軸與張力軸之角度變小而增加。主應力大小與角度變化關係隨硬度增加或形狀變扁平（或細長）而愈加顯著。
• 英文摘要： Internal stress in and around equiaxed ellipsoidal inclusions is evaluated in order to understand theroles of inclusion in ductile fracture. The calculation is based on a continuum model by assuming: (1) thematrix is isotropic, perfectly elasto-plastic and deformed by tension, (2) the plastic flow in the matrix isuniform, (3) no plastic relaxation has occurred in the matrix during loading, (4) the inclusion is isotropicand perfectly elasto-plastically-non-deformable. It is found that, unless the non-deformable inclusioncracks, the cavities always nucleate at the matrix-inclusion interface. The plastic strain required to deco-here the interface decreases as the longer axes of the particles are oriented more closely along the tensileaxis. This angular dependency becomes stronger as the hardness of the particles increases. It is also foundthat the plastic strain needed for the nucleation of cavities decreases as the hardness of the particles in-creases and increases when the particles become flatter. The maximum principal stress in the inclusion istensile and is larger in harder particles, it is also larger in particles with their longer axis oriented moreclosely along the tensile axis. This angular dependency becomes stronger as the particles become flatteror slender. With same particle shape, this angular dependency becomes stronger as the hardness of theparticles increases.
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