The study of crack propagation behavior in functionally graded plate due to thermal load

本课题包括两个部分：[1]热冲击下功能梯度板（FGP）中裂纹的产生模式;[2]热冲击下FGP中裂纹的扩展模式。[1]热冲击作用下功能梯度板（FGP）中裂纹的扩展模式通过数值模拟，我们得到了以下结果：（1）热应力可以在裂纹附近区域释放。（2）由于远离裂纹的边界表面上的热应力随时间均匀地增加，因此不能确定裂纹开始的位置。然而，可以确定最小裂纹空间。[2]热冲击下功能梯度板中裂纹的扩展模式（1）分析了含Griffith裂纹的功能梯度板的热应力问题。而我们研究的是带有两条Griffith裂纹的FGP中的热应力问题。由于材料的非均匀性，求解双裂纹FGP问题非常困难 ...更多信息 额。（2）情况A：具有两个初始裂纹的FGP中的裂纹扩展模式。（1）裂纹扩展有四种模式：1）裂纹沿厚度方向沿着直线扩展，并在某一位置停止; 2）两条裂纹相向而行，相向而行; 3）两条裂纹相向而行，相向而行;（2）双裂纹情况下的分层深度小于单裂纹情况下的分层深度。（3）FGP的裂纹间距、加热温度和成分分布对裂纹扩展方向有很大影响。（4）当各裂纹相互接近时，各裂纹不接触，沿厚度方向沿着转向。（5）当两条裂纹沿同一方向弯曲时，后一条裂纹避开前一条裂纹扩展。（3）情况B：具有三个相同长度的初始裂纹的FGP中的裂纹扩展模式。（1）中间裂纹沿直线扩展，并在一定位置处停止;（2）外裂纹的扩展方式与两种裂纹扩展方式基本相同。（3）各裂纹不接触。少

This Research project consists of two parts : [1]the crack generation patterns in the functionally graded plate (FGP) under thermal shock, and [2]the crack propagation patterns in the FGP under thermal shock.[1]the crack generation patterns in the functionally graded plate (FGP) under thermal shockWe could obtain following results by numerical simulations. (1)The thermal stresses can be released in the region near the crack. (2)Since the thermal stresses on the boundary surface far away from the crack uniformly increase with time, the position where a crack initiates cannot be determined. However, minimum crack space can be determined.[2]the crack propagation patterns in the functionally graded plate (FGP) under thermal shock(1)We could analyze the thermal stresses problems in the FGP with a Griffith crack. However we are studying the thermal stresses problems in the FGP with two Griffith cracks. It is very difficult to solve the FGP with two cracks due to non-homogeneous material prop … More erties.(2)Case A : Cracks propagation patterns in the FGP with two initial cracks.(1)There are four cracks propagation patterns : 1)The crack propagate straightly along the thickness and arrests at the certain position, 2)Two cracks curve with opposite direction going away for each other, 3)Two cracks curve with opposite direction approaching for each other, 4) Two cracks curve with same direction.(2)The delamination depth in the case of two cracks is shorter than that of a single crack.(3)The space between the cracks, heating temperature and composition profile of the FGP largely affect the crack propagation direction.(4)When each crack approaches for each other, each crack does not contact and turns along the thickness.(5)When each crack curves with same direction, the latter crack propagates by avoiding the former crack.(3)Case B : Cracks propagation patterns in the FGP having three initial cracks with same length.(1)The middle crack propagates straightly and arrests at certain position.(2)The behavior of the crack propagation patterns of the outer cracks is about same as two crack propagation pattern.(3)Each crack does not contact. Less