本論文是以視定塑性力學法探討8090鋁鋰合金在多軸應力狀態下之超塑性成形特性。利用不同成形階段之試件，研究在成形過程中，試件的變形狀態、試件厚度分佈及局部應變速率等之情形。實驗結果顯示，柱狀杯形零件在超塑性成形過程中，應該分為變形板片觸底前及觸底後兩個不同階段來探討其變形特性。成形試件中之空孔狀態，除了受到成形速率的影響外，試件較先貼模的部分，空孔量可能因為產生燒結作用造成空孔收縮的現象，而最後導致空孔量的減少。 Effect of multi-axial stress on deformation characteristics of a superplastic aluminum alloy 8090 was studied by use of Visioplasticity in this work. Several interrupted tests were performed to bulge the sheets to various depths for different strain rates
