Load transfer at imperfect interfaces--dislocation-like model

A dislocation-like model describing the boundary conditions of a partially debonded interface is verified experimentally. The effect of the imperfect interface on the load transfer is studied by photoelastically measuring the elastic deformation in bimaterials due to an inclusion with dilatational misfit strain. The boundary conditions to be modeled are that the radial and the tangential tractions are continuous across the interface and the displacements may be discontinuous from one solid to another. The discontinuity of displacement across the interface is assumed linearly proportional to the displacement at the interface of the constituent where the stress source is. The maximum shear stress distributions measured from the isochromatic fringe patterns are in good agreement with the theoretical calculations. The results show that an imperfect interface could be viewed as a continuum entity with interface rigidity as proposed by the dislocation-like model.     

Study on Interface between Sub—micron Particles and Matrix in Al2O3p／Al Composites

The microstructural characteristic of 1070Al matrix composites reinforced by 0.15μm Al2O3 particles whose volume fraction was 40% was investigated by TEM and HREM.The results showed that the interface between the matrix and reinforcements was clean and bonded well,without any interfacial reaction products.There were some preferential crystallographic orientation relationships between Al matrix and Al2O3 particle because of the lattice imperfection on the surface of Al2O3 particles.     

AVR嵌入式单片机接口技术与应用

AVR单片机内嵌Flash，置有ADC和模拟比较等电路接口，采用快速存取寄存器文件和快速单指令周期，其程序与数据存储器分开，通过SPI和编程器可对Flash存储器编程，在分析AT90S8515芯片定时／计数器、I／O端口、通用串行口UART、模拟比较器等接口基础上，设计了信号发生器、频率计以及与PC机串行通信接口电路，给出了数字信号发生器原理图和程序流程图，频率计原理简图与程序流程图。     

Interface crack between two interface deformable piezoelectric layers

Based on an interface deformable piezoelectric bi-layer beam model, a bonded piezoelectric bi-material beam with an interface crack perpendicular to the poling axis is analyzed within the framework of the theory of linear piezoelectricity. The layer-wise approximations of both the elastic displacements and electric potential are employed, and each sub-layer is modeled as a single linearly elastic Timoshenko beam perfectly bonded together through a deformable interface. Using the impermeable crack assumption, the closed form solutions for the energy release rate (ERR) and crack energy density (CED) are derived for the layered piezoelectric beam subjected to combined uniformly distributed electromechanical loading. Based on superposition principle, both the ERR and CED and their components are all reduced to the functions of the crack tip loading parameters. Loading dependence of the total CED with respect to the applied electric field is manifested with the analytical results, showing that there is a transformation from an even dependence to an odd dependence for the normalized CED when the applied mechanical loading increases. Compared with the commonly used equivalent single layer model, the proposed analysis augments the crack driving force by alleviating the stress concentration along the interface and thus increases the loading parameters at the crack tip. The proposed model provides improved solutions for fracture analysis of piezoelectric layered structures and sheds light on the loading dependence of the fracture parameters (i.e., the ERR and CED) with respect to the applied electromechanical loadings.     

Thermoplastische Hybridlaminate mit variabler Metallkomponente

Hybrid laminates combine the positive properties of the metal and fibre reinforced plastic (FRP) components. Advantages of the FRP, like formability, recyclability as well as suitability for mass production, provide an outstanding advantage over thermosetting matrices. For the production of the hybrid laminates, at first continuous fibers and thermoplastic films are pre‐consolidated to fibre‐reinforced unidirectional tapes. Subsequently, these are pressed together with the metal component in a loadcapable optimized arrangement. Thereby the interface between the FRP and the metal foils is of crucial importance. This paper focuses on hybrid laminates with carbon‐fiber reinforced polyamide (CF‐PA6) functioning as core layers and glass‐fiber reinforced polyamide (GF‐PA6) as intermediate layers between the centre and metal component. Laminates in 2/1 and 3/2 structure with two respectively three metal layers and one respectively two FRP layers are examined. For the metal foil, the aluminium alloy EN AW‐6082 and the titanium alloy Ti3Al2.5V (Grade 9) are used. The production of these laminates, development and adjustment of the interface and the evaluation of mechanical properties are investigated in this article.     

Combined effects of fiber/matrix interface and water absorption on the tribological behaviors of water-lubricated polytetrafluoroethylene-based composites reinforced with carbon and basalt fibers

Tribological behaviors of two PTFE-based composites reinforced with carbon fibers and basalt fibers sliding against stainless steel under water lubrication were investigated and compared with those of pure PTFE. Results showed that carbon fibers were well bonded with PTFE matrix by dendritic PTFE nano-ribbons in a Boston ivy-like manner, but the basalt fibers were poorly bonded with the matrix. Due to the great accelerating effect of poor fiber/matrix interfacial adhesion on water absorption, BF/PTFE with the highest crystallinity unexpectedly showed the highest water absorption, resulting in serious matrix plasticization and degradation of fiber/matrix interfacial adhesion. As a result, as the reinforcement failure of basalt fibers occurred, BF/PTFE exhibited the highest wear rate. Instead, because good fiber/matrix interfacial adhesion was favor of the resistance to water intrusion, CF/PTFE composite was not dominated by remarkable matrix plasticization and fiber/matrix interface degradation, and showed the lowest wear rate.     

基于Virtools的高级交互式虚拟现实模型库的建立

在产品的设计和展示中,虚拟现实模型可取代实物模型,达到节约成本、方便使用的目的。以虚拟现实引擎Virtools为平台,利用3DMax建立虚拟模型,导入到Virtools中建立虚拟模型库。讨论3DMax和Virtools的接口问题,并对虚拟模型进行了各种交互控制,进而形成了具有Virtools内嵌数据库支持的虚拟模型库。实现的高级交互控制虚拟模型库增加模型库的沉浸感,使虚拟现实技术更加实用。     

PCI接口芯片9080及其应用

CI9080是PLX公司开发的支持主从模式传输的PCI接口芯片。介绍了PCI总线的特性和PCI9080的主要特点、芯片内部结构,并详细分析了DMA,Direct Master,Direct Slave的传输特性和总线周期信号响应过程,以及PCI9080的总线工作模式、配置空间加载方式、上电初始化过程。最后给出了一个PCI数据采集卡的硬件设计框图和具体功能模块说明,旨在说明如何通过PCI9080设计PCI总线适配卡。     

First-principles Study on the Ductility Effect of Zirconium and Its Distinct Behavior from Boron to Restrain Hydrogen-induced Embrittlement in Ni-Ni3Al Alloys

By studying a cluster model containing Ni region （phase）, NiaAI region （phase） and Ni/Ni3Al region （interface） with a first-principles method, the occupation behavior and the ductility effect of zirconium in a Ni-Ni3Al system were investigated. It is found that zirconium has a stronger segregation tendency to Ni region than to Ni3Al region. The bond order analyses based on Rice-Wang model and the maximum theoretical shear stress model, however, show that zirconium has different degrees of ductility effect in these three regions, which originates from its different ability to increase the Griffith work of interracial cleavage 2γint and to decrease the maximum theoretical shear stress τmax. In addition, it is revealed in this paper that the distinct behavior of zirconium from boron to restrain hydrogen-induced embrittlement can be attributed to their different influences on the crystalline and electronic structures in Ni-Ni3Al alloys.     

Structural and electrical properties of annealed CdSe films on Ni substrate

Preparation and characterization of CdSe thin film semiconductors, prepared by cathodic electrodeposition from an acid sulphate solution (CdSO₄-SeO₂) before and after thermal treatment in nitrogen atmosphere, were investigated. The effect of the bath temperature and how it affects the cadmium selenide (CdSe) deposits were studied. The formation of compact barrier layers of zinc blende CdSe was attained. Scanning electron microscopy and X-ray diffraction patterns present a remarkably intense cubic structure, even after thermal treatment. The Ni/CdSe/Au structure may exhibit rectifying properties depending on the temperature during the electrodeposition. Thermal annealing in nitrogen gas increases the conductivity of CdSe and intensifies the rectification properties of the Ni/CdSe/Au structure.