(哈爾濱工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，哈爾濱 150001)
摘 要: 利用數(shù)值模擬和塑性理論分析AZ31B鎂合金管材的熱態(tài)內(nèi)壓成形過(guò)程的變形機(jī)理，找出臨界起皺應(yīng)力、應(yīng)力狀態(tài)及皺紋形狀的變化規(guī)律。結(jié)果表明：隨著溫度升高，管材軸向抗起皺能力下降，其機(jī)理是材料的屈服強(qiáng)度和彈性模量隨溫度升高而下降；皺峰和皺谷處應(yīng)力軌跡均在環(huán)向應(yīng)變伸長(zhǎng)和軸向應(yīng)變壓縮的區(qū)域；隨著補(bǔ)料量的增大，皺峰處應(yīng)力向壁厚減薄的方向發(fā)展，皺谷處應(yīng)力向壁厚增加的方向發(fā)展；內(nèi)壓與材料屈服強(qiáng)度之比(相對(duì)壓力)決定初始屈服時(shí)皺峰和皺谷處壁厚的變化情況，即溫度較高時(shí)，相對(duì)壓力較大，初始屈服時(shí)皺峰和皺谷處應(yīng)力狀態(tài)越易處于管壁呈減薄趨勢(shì)的區(qū)域；當(dāng)溫度較低時(shí)，相對(duì)壓力較小，初始屈服的皺峰和皺谷處的應(yīng)力狀態(tài)越易處于管壁有增厚趨勢(shì)的區(qū)域；隨著溫度升高，相同加載路徑下皺紋的高度和波長(zhǎng)增大，皺紋趨向于向中間移動(dòng)，且波數(shù)減少。
關(guān)鍵字: 鎂合金；熱態(tài)內(nèi)壓成形；起皺行為；數(shù)值模擬
magnesium alloy tube
（School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China）
Abstract:The deformation mechanism was analyzed for an AZ31B magnesium alloy tube in warm hydroforming process by numerical simulation and plasticity theory. The critical wrinkling stress, the stress state and the shape of the wrinkles were obtained. It is shown that the yielding strength and the elastic modulus decrease as the temperature rises, which makes the anti-winkling ability of the tube decrease. The stress loci lie at the zone where the circumstantial strain elongates and axial strain is compressive for both the top zone and the bottom zone of the wrinkles wave. The stress at the top zone of the wrinkles wave tends to make the wall thickness thin as the feeding increases. The stress at the bottom zone of the wrinkles wave tends to make the wall thickness thicken. The ratio of the internal pressure to the yielding strength (relative pressure) determines the variation of the wall thickness. If the forming temperature is higher, the relative pressure is greater, which makes the thinning trend of the wall thickness easier at the initial yielding time. If the forming temperature is lower, the relative pressure is smaller, which makes the thickening trend of the wall thickness easier at the initial yielding time. The height and length of the wrinkles wave get larger for the same loading path as the temperature rises. The wrinkles tend to move towards the middle part. The wrinkles wave number decreases.
Key words: magnesium alloy; warm hydroforming; wrinkling behavior; numerical simulation
