自1948年Tabor提出壓痕應變的概念後，許多研究提出壓痕應變的定義並探討拉伸與壓痕應力-應變曲線之關聯性，卻忽略了最直接影響壓痕應力-應變曲線的是接觸深度與接觸半徑。為此，本研究利用有限元素法結合等向塑性與晶體塑性兩種模型模擬多晶銅壓痕變形，透過定義壓痕應力與應變來得到壓痕應力-應變曲線，與拉伸實驗比較。其次討論接觸深度對壓痕應力-應變曲線行為的影響，最後也探討兩種組成律模型對壓痕應力-應變曲線的影響。
　　壓痕應力-應變曲線的模擬結果顯示，接觸深度影響壓痕曲線的行為主要為壓痕應力的大小。當接觸深度大於壓痕深度(pile-up)時，壓痕塑流曲線將往小應力移動，類似真實應變的Milman應變最接近。接觸深度等於壓痕深度時，最佳應變為在接觸點的應變Ahn應變。當接觸深度小於壓痕深度(sink-in)時，工程應變的Tabor、Johnson、Kalidindi應變更符合拉伸曲線。
　　等向塑性與晶體塑性兩種模型的模擬結果顯示，晶體塑性模型的壓痕應力-應變曲線高於等向塑性模型。儘管在兩個模型中接觸深度相等，但晶體塑性模型的負載值較高，其可能的原因推測為在晶體塑性模型中，塑性變形僅限於12種組合即12種滑移系統。為了達到相同變形量，需更大的負載來達成，然而這種結果使得晶體塑性模型的行為更符合拉伸實驗曲線。

　　Indentation stress-strain curves of polycrystalline copper from spherical indentation deformation are　simulated using finite element method with isotropic and crystal plasticity model. Effect of contact depth on indentation stress-strain curve is discussed, and the indentation stress-strain curves with two models are compared to the experimental tensile flow curve in order to explore the feasibility of the indentation stress-strain method. The contact depth is inversely proportional to the indentation stress and it can preliminarily determine the best indentation strain. At the indentation stress-strain curves with isotropic and crystal plasticity model, the results of crystal plasticity are always higher than isotropic model. The deviation happens because CP only has 12 slip systems in each element to deform, CP model need to apply a larger load to achieve the same　deformation. However, the indentation stress-strain curves with CPFEM agreed with the tensile flow curve.

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