基于细观GTN模型的蠕铁气缸盖损伤研究
发布时间：2018-10-15 19:05
【摘要】：气缸盖作为内燃机中结构和载荷最复杂的零件之一,容易形成不同位置不同程度的破坏,成为制约发动机寿命的重要因素。本文以蠕铁气缸盖作为研究对象,从细观损伤力学的角度出发,运用GTN损伤模型对缸盖损伤进行分析,利用有限元逆向法结合试验和仿真确定模型中的损伤参数。采用了缸盖火力板结构模拟件,基于GTN损伤模型对缸盖进行损伤分析,通过孔洞体积分数的演变从细观损伤的角度描述了材料宏观裂纹的产生。主要研究方法和结论如下:利用用于材料试验的单向拉伸圆试棒,在室温、300℃、500℃下进行了单向拉伸试验,得到了各温度下的应力应变关系曲线。对拉伸试件初始阶段、颈缩阶段、断裂阶段切取用于扫描电镜观测的切片,得到扫描图像,再利用图像处理软件IPP进行处理,初步得到孔洞长大过程参数0f=0.00328,cf=0.021,Ff=0.0412。建立拉伸试件的有限元模型,利用有限元逆向法通过正交试验对孔洞形核参数的取值进行计算分析,最终确定了n?=0.1,ns=0.075,nf=0.025。在此基础上,对室温下的GTN损伤参数进行温度修正,以高温下的试验应力应变曲线为参照,调整GTN参数使仿真值吻合试验值,在此过程中确定了nf、nS和n?对材料仿真计算的力学行为的影响。制备了与缸盖火力板等效的结构模拟件,分别讨论了孔洞体积分数与等效塑性应变以及颈缩后Mises等效应力的关系,通过分析得到孔洞体积分数与等效塑性应变的变化趋势基本一致;孔洞不断增大,损伤不断累积,材料承载能力下降,最先达到临界孔洞体积分数的节点应力最早开始下降。从孔洞体积分数的演化预测孔洞体积分数最先达到破坏体积分数的进气门鼻梁区首先出现裂纹,从细观损伤角度解释了缸盖宏观裂纹的产生。
[Abstract]:As one of the most complicated parts in internal combustion engine, cylinder head is easy to be destroyed in different positions and degrees, and becomes an important factor restricting engine life. In this paper, the damage of vermicular iron cylinder head is analyzed by using GTN damage model from the point of view of mesoscopic damage mechanics, and the damage parameters in the model are determined by finite element reverse method combined with test and simulation. The damage analysis of cylinder head based on GTN damage model is carried out by using the cylinder head fire plate structure simulator. The macroscopic crack generation of material is described from the point of view of mesoscopic damage through the evolution of pore volume fraction. The main research methods and conclusions are as follows: uniaxial tensile tests were carried out at room temperature, 300 鈩，
本文编号：2273534
[Abstract]:As one of the most complicated parts in internal combustion engine, cylinder head is easy to be destroyed in different positions and degrees, and becomes an important factor restricting engine life. In this paper, the damage of vermicular iron cylinder head is analyzed by using GTN damage model from the point of view of mesoscopic damage mechanics, and the damage parameters in the model are determined by finite element reverse method combined with test and simulation. The damage analysis of cylinder head based on GTN damage model is carried out by using the cylinder head fire plate structure simulator. The macroscopic crack generation of material is described from the point of view of mesoscopic damage through the evolution of pore volume fraction. The main research methods and conclusions are as follows: uniaxial tensile tests were carried out at room temperature, 300 鈩，
本文编号：2273534
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