應用連體損傷力學於微金屬板材拉伸斷裂之研究

A Study of Tensile Fracture in Micro Sheet Metal Forming by Using Continuum Damage Mechanics

蔡傑丞(Jie-Cheng Tsai)

指導教授 ： 葉豐輝

淡江大學/工學院/機械與機電工程學系碩士班/碩士(2010年)

https://doi.org/10.6846/TKU.2010.00387

摘要

本文乃利用動態有限元素法結合連體損傷力學，進行微金屬板材拉伸斷裂分析之研究，探討拉伸負荷、伸長量、破斷面及變形歷程等，並與拉伸試驗做比較。
本研究首先使用Swift Model應力應變曲線，取代Lemaitre損傷理論中之冪次方(Power Law)應力應變曲線，重新推導彈塑性損傷模型。其次依據ASTM E345規範，進行銅箔拉伸試驗，得到相關機械性質；再利用新的損傷模型計算銅箔損傷曲線，做為銅箔拉伸斷裂模擬分析之依據。
本研究之實驗結果得知，銅箔試片拉伸斷裂後之伸長量為10.993mm，其破斷面在試片中間且趨近於水平。此外，由數值分析結果得知，模擬銅箔拉伸斷裂之伸長量為11.468mm，其破斷面亦在料片中間且為水平方向。本文經由數值分析與實驗結果比較，可證實有限元素法結合所推導之彈塑性損傷模型，可正確模擬微金屬板材拉伸斷裂分析。

關鍵字

微成形 ； 拉伸試驗 ； 動態有限元素法 ； 連體損傷力學

並列摘要

The thesis uses dynamic finite element method and continuum damage mechanics to study the tensile fracture in micro sheet metal forming. The tensile load, elongation, fractured surface and deformation history are discussed and compared with the experimental results.
First, instead of using power law for stress-strain curve in Lemaitre damage model, Swift model is applied to re-derive a new elastic-plastic damage model. Secondly, the tensile test of copper foil is conducted according to ASTM E345 standard and the mechanical properties are obtained. Subsequently, the accumulated damage curve of copper foil is generated for the criterion of fracture by the new elastic-plastic damage model.
The experimental results show that the elongation of copper foil specimen at break is 10.993mm. The fractured surface is at the middle of specimen and the direction is approximately horizontal. Besides, the elongation by numerical analysis at break is 11.468 mm and the position and direction of fractured surface are also close to the experimental results. By comparison of numerical and experimental results, it shows that the combination of finite element method and elastic-plastic damage model can be used to simulate the tensile fracture in micro sheet metal forming correctly in the thesis.

並列關鍵字

Micro Forming ； Tensile Test ； Dynamic Finite Element ； Continuum Damage Mechanics

參考文獻

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