Using the LUCID method to optimize the acceptability of shared interfaces

The Logical User Centred Interface Design (LUCID) method has been shown to provide a development approach which is both user-centred and which, with respect to selected usability criteria, leads to the identification of the optimum interface. Previously published evidence has focused on factors internal to the design of the interface itself. In this paper, the authors show how Taguchi techniques for total quality management, which are integrated within the method, can be extended to analyse external factors such as diversity within the user groups of shared interfaces. Application of the method to global, international and local interfaces is discussed.     

Advances in numerical modeling of environmental barrier coating systems for gas turbines

Advanced gas turbines pursue efficiency improvement by employing high-temperature lightweight materials. Ceramic matrix composites are the most promising candidates for hot section components. However, they generally require environmental protections for long-term stability in harsh working conditions subjected to water vapor volatilization, accelerated oxidation, severe corrosion and erosion. To this end, environmental barrier coating systems (EBCs) have substantially progressed as an integral design element in the past two decades. As a versatile numerical method, finite element analysis has been widely applied in the investigations of EBCs from stress modeling to service life prediction. This article reviews recent advances in the numerical studies of EBCs for gas turbines, covering fundamental analyses of stress state and heat transfer, elucidations of fracture and damage mechanisms, as well as applications in service conditions. Current numerical solutions, understandings and potential directions are discussed respectively, with general remarks on technical development in the end.     

合金钢热障涂层等离子喷涂及高温力学特性研究

目的研究等离子喷涂热障涂层微观组织与高温力学性能,为热障涂层在合金钢的应用及其失效机制提供理论支撑。方法采用等离子喷涂技术在30Cr Mn Si A钢基体上制备Ni Co Cr Al Y/YSZ热障涂层,利用扫描电镜显微观察、物相分析、热震试验、拉伸试验等技术方法,考察涂层在高温条件下的失效行为。结果合金钢等离子喷涂热障涂层为典型双层层片状结构,YSZ涂层仅含有稳定四方相。800℃时,涂层试样拉伸试验后的断裂载荷与无涂层试样相比高10%。热障涂层的抗热震性良好,经900℃热震循环试验10次后,涂层完好;经1000℃热震循环6次后,涂层剥落失效,剥落面位于粘结层与基体之间。热震循环过程中,钢基体被氧化甚至腐蚀。涂层试样边缘产生应力集中,随着热震次数的增加,裂纹逐渐扩展,最终导致涂层成块剥落。温度由700℃升至900℃,Ni Co Cr Al Y涂层硬度下降幅度大于YSZ涂层和30Cr Mn Si基体。结论粘结层与钢合金基体的热膨胀不匹配是导致热震试验涂层剥落的主要原因。热障涂层的隔热作用使涂层试样的基体温度较低,导致其断裂载荷与无涂层试样相比较高。     

Simulation on the Melt Flow in Laser Full Penetration Welding with a Model Including a Non-Rotational Symme-try Keyhole Based on Energy Balance

A three dimensional model including a non-rotational symmetry keyhole of which the geometry is calculated base on the energy balance at keyhole wall is created to simulate the heat transfer and fluid flow within the molten pool during laser full penetration welding of titanium alloy plate.In order to take into account the effects of multiple reflections within the keyhole,a ray tracing method is employed and the coordinate dependent heat flux obtained is exerted on keyhole wall during the simulation on the heat transfer and fluid flow within molten pool.Furthermore,the computed weld cross sectional profile is compared with the experimental result to verify the model and it is fond that the simulation result is consists with experimental result.