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

本研究由两部分组成：[1]功能梯度板在热冲击下的裂纹扩展模式，[2]功能梯度板在热冲击下的裂纹扩展模式。[1)功能梯度板在热冲击下的裂纹扩展模式。(1)热应力可以在裂纹附近释放。(2)由于远离裂纹的边界面上的温度应力随时间均匀增加，因此无法确定裂纹的起裂位置。[2]热冲击下功能梯度板(FGP)中的裂纹扩展模式(1)我们可以分析具有Griffith裂纹的功能梯度板中的热应力问题。然而，我们正在研究具有两个Griffith裂纹的FGP中的温度应力问题。由于非均匀材料支柱…的存在，解决含两个裂纹的FGP是非常困难的(2)情况A：含两个初始裂纹的FGP中的裂纹扩展模式。(1)有四种裂纹扩展模式：1)裂纹沿厚度直线扩展并在某一位置滞留，2)两个裂纹相互背离相反方向的曲线，3)两个裂纹相反方向相互靠近，4)两个裂纹沿同一方向弯曲。(2)双裂纹情况下的分层深度小于单裂纹的分层深度。(3)两个裂纹之间的间距，加热温度和FGP的成分分布对裂纹扩展方向有很大影响。(4)当每个裂纹相互靠近时，每个裂纹不接触并沿厚度方向转动。(5)当每个裂纹沿同一方向弯曲时，后一个裂纹通过避开前一个裂纹而扩展。(3)情况B：FGP中有三个相同长度的初始裂纹的裂纹扩展模式。(1)中间裂纹直线扩展并在一定位置停滞。(2)外部裂纹的扩展模式与两个裂纹扩展模式基本相同。(3)每个裂纹不接触。较少

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