Applied Mechanics and Materials Vols. 52-54

Abstract: Adhesion of a coating on its substrate is a crucial parameter determining performance and reliability of coating-substrate system. In this work, the uniaxial tensile and cross-sectional indentation tests are used to investigate the adhesion between the brittle Cr coating and the ductile steel substrate. The uniaxial tensile test results show the maximum shear flow stress level of the ductile steel substrate can only serve as a lower bound estimate on the ultimate shear strength of the interface. The cross-sectional indentation test results show the interfacial decohesion does not occur prior to the cracking of the brittle Cr coating.

Abstract: Platelet transpiration cooling is one of the key techniques for the developing reusable launch vehicle. The thinner of the platelet, the better effect plate transpiration will gain. Meanwhile, the platelet unit may get wrinkled if thermal stress is large enough. One-dimensional non-equilibrium model is adopted to analyze the heat transfer characteristics of platelet transpiration cooling. The assumption of rectangular plate with three-side simple supported and one-side free is taken and Galerkin method is applied for analyzing the stability of platelet unit. Analysis indicates that as the heat transfer intensity increases, the thermal soaking depth decreases, while more coolant is needed to keep the heated wall at design temperature. Also, the critical thickness for the platelet not to get wrinkled gets larger with the increasing thermal soaking depth.

Abstract: Ultrasonic is one of the most common uses of non-destructive evaluation technique. It could detect flaws inside the structure and on the surface such as voids, holes and cracks. In this investigation, a 304 steel block with a surface-breaking crack was fabricated. A series of test specimen with different depths of surface-breaking crack ranging from 2mm to 9mm was fabricated. The depth of the surface crack was evaluated by the pulse-echo ultrasonic technique. In this work, 2.25MHz, 5MHz and 10MHz of incident waves were employed to detect the depth of the surface-breaking crack. The effect of incident angle on the measuring accuracy was investigated. Experimental results showed that the accuracy of crack sizing detection by ultrasonic technique is not only dependent on the frequency of the incident wave but also dependent on the incident angle.

Abstract: Based on the analysis of the PMSM’s mathematic model, we’ll use the Matlab/Simulink to construct the simulation model of the precision CNC lathe knife tower servo system. The control system uses the classical three closed structure. According to the servo system's performance requirements, we'll do the parameter selection and simulation. The simulation result proves the validity of the model and provides the theory basis for the system's design and debug.

Abstract: The assembly of proton exchange membrane fuel cell (PEMFC) is the important factor for the performance. The achievement of proper design will improve the pressure distribution and the electrical contact resistance between fuel cell parts. The assembly pressure affects the contact behavior between of bipolar plate and gas diffusion layer (GDL). In this study, finite element analysis (FEA) was used to analyze the behavior of single cell fuel cell under the variation of assembly pressure. It shows 3D of deformation, and the compression pressure every part of the fuel cell components. The simulation varied the torque assembly from 1 Nm to 3 Nm with increment 0.5 Nm. The simulation using FEA shows that high assembly pressure also affects to the high deformation and stress in the components of fuel cell. This phenomenon affects to the performance of PEM fuel cell.

Abstract: In view of application requirements, control axes, the development cycle and other factors of open CNC machine tools, we consider the modular as the guiding ideology and propose a design method of three-dimensional engraving and milling machine based on open CNC system. In this paper we make a detailed design for mechanism structure and control system. Experiments show that this machine has milling and engraving capabilities, can process metal and non-metallic parts, which is a high efficiency, multi-function numerical control equipment.

Abstract: Completed structure of milling machine design based on open CNC system through the combination of multi-axis motion controller and the way of NC embedded PC. The traditional CNC milling machine combined with technology of many aspects of Precision machinery, electronics, electric drive, automatic control, automatic detection, and computer and so on. High-precision high efficiency and high flexibility of the CNC milling machine makes it has more widely applications. But there are some problems, for example, based on the traditional CNC milling system for work-piece processing is also not very convenient, and traditional CNC system must be G code programming first, then process work-piece, in addition, as the closed nature of traditional CNC systems, products of hardware and software of the CNC manufacturers are not compatible, and system’s training and maintenance costs much, we put forward the open CNC system, then we start to research and analysis the Milling Machine Design Based On Open CNC System.

Abstract: A kernel technology of the bimetal cylinder liner of mud pump concerning industrialization is introduced, based on which the optimal design of chemical composition and material structure of the inner cylinder liner, investigation of the interleaving centrifugal foundry process of dual liquid and the development of the centrifugal foundry equipment for the dual liquid are made. Compared with the present heating assembling process used in production, the new technology has demonstrated some advantage for longer service life, lower cost of production, and so on, consequently leading to the industrialization of the mud pump liner made from integrative composite material.

Abstract: The generalized elasticity solutions are obtained in this paper by symmetries from Lie transformations. The symmetries of the bihamonic equation are obtained by mathematica package SYM. The several invariant solutions are found by solving the corresponding ordinary differential equations from Lie transformations. The superposition of invariant solutions, corresponding to an eigenfunction expansion, could yield the generalized elasticity solutions in rectangular coordinates and polar coordinates, where the eigenvalues arises from the invariance of bihamonic equation.

Abstract: Drill and blast method becomes unfavorable for deep mining of hard rock. Mechanical excavation with roadheader EBZ160TY was trialed at work face with hard rock and high ground stress. Work procedure and performance of the roadheader were recorded and analyzed. The results showed that, roadheader EBZ160TY, with designed excavating strength of 80 MPa, presented amazingly good performance in hard rock with strength of 148 MPa and consumed less cost compared to drill and blast method. High stress was found to play positive role in improving its working ability. Under the gentle disturbance of roadheader excavation, the high ground stress brings the surrounding rock mass to deform into yield and lets the stress/strain energy transform into fracture energy of rock fragmentation. With the push and rotation of roadheader, structural instability of confined high-stressed particle aggregate other than rock failure by mechanical wearing happens. The results show a good application prospect for roadheader in hard rock excavation especially at deep level.