Key Engineering Materials Vols. 419-420

Abstract: Drop test is one of the common methods for determining the reliability of electronic products under actual transportation conditions. The aim of this study is to develop a reliable drop impact simulation technique. The test specimen of a printed circuit board is clamped at two edges on a test fixture and mounted on the drop test machine platform. The drop table is raised at the height of 50mm and dropped with free fall to impinge four half-spheres of Teflon. One accelerometer is mounted on the center of the specimen to measure the impact pulse. The commercial finite element software ANSYS/LS-DYNA is applied to compute the impact acceleration and dynamic strain on the test specimen during the drop impact. The finite element results are compared to the experimental measurement of acceleration with good correlation between simulation and drop testing. With the accurate simulation technique, one is capable of predicting the impact response and characterizing the failure mode prior to real reliability test.

Abstract: Piezoelectric materials have the advantage of being lightweight, temperature insensitivity low-cost, easy of implementation that can be utilized for passive and active control of structural vibration. They can be surface bonded or embedded in the structures with slight modifications and without significantly changing the structural stiffness of the system. In this investigation, two piezoelectric actuators are symmetrically embedded in a simply supported plate. Electric voltages with the same amplitude and opposite sign are applied to the two symmetric piezoelectric actuators, resulting in the bending effect on the plate. The bending moment is derived and applied to the simply supported plate. The harmonic response of the simply supported plate excited by the piezoelectric actuators is derived and compared with the finite element solution to show the validation of present approach. The effects of the location and exciting frequency of the piezoelectric actuators on the response of the plate are presented through a numerical study.

Abstract: The purpose of this study is to present a novel concept for inline vibrating conveyors, and verify its feasibility by kinematic simulation. First, new conveyor is presented, and its merits are discussed. Then, its kinematically equivalent linkage is described. Moreover, the kinematic dimensions are investigated from its geometry. Finally, the solid model for the proposed design is established, then kinematic simulation is performed by ADAMS software. The simulation results indicate that the proposed new design can effectively advance the workpiece.

Abstract: Existing conceptual design methods mainly focus on component modeling and representation, which makes them insufficient to help in the conceptual design stage. Port ontology, as an approach to formally expressing product design, has been effectively applied to concept description of a product. An incidence matrix support for product conceptual design based on port ontology is given in this paper. It formally represents and organizes product information in both functional ontology and physical domain in a hierarchy. Port compatibilities are used to map and link the two components. This makes it possible to build incidence matrix and decompose it into an independence matrix, and allow designers from different backgrounds with various interests to access the design ontology. A multilevel matrix is constructed to generate principle schemes of products at different levels of abstraction, which facilitates design decision-making through the whole conceptual design stage. A case study is also given to demonstrate the proposed approach.

Abstract: The apparent viscosity of aircraft grease with different nano-particles content, temperature and shear rates were studied using a rotational viscometer. The rheological properties of two types of aircraft grease, the basic grease and the one with nano-particles additives, were investigated using a rheometer. The results indicated that the apparent viscosity increases with the increase of nanoparticle concentration with the given ratio of nano-particles added. It was also found that the grease with and without the nano-particles both have yield stresses and clear shear-thinning properties. The shear-thinning phenomenon of the grease containing nano-particles is more evident than that of the basic grease. The experimental results also reveal that the rheological characteristics of both types of grease fall in Herschel-Bulkley class, and the nano-particles have a significant influence on the rheological parameters. At the end, the rheology mechanism was discussed based on the entanglement and orientation theories.

Abstract: Most of the lubricants are made of mineral oil which has bad biodegradability, and, hence, seriously contaminate the environment. To minimise the lubricants’ impact on the environment, this research developed a new type of lubricant, titanium complex grease. Its base oil is the admixture of vegetable oil and mineral oil. Its production method and experimental results are presented in this paper. The friction, wear and physical-chemical properties of the grease were investigated. The morphology of wear scar of steel ball was observed using the sweep electron microscope. The results obtained contribute to the further development of environmentally friendly lubricants.

Abstract: A new framework of decision-making is proposed in this paper to accommodate the application of quality function deployment (QFD) integrated with TRIZ. In the proposal framework, Ideal Final Result (IFR) oriented decision-making process is introduced for the innovation design process in order to select the best solution from alternatives which are generated by TRIZ and consistent with the laws of technical system evolution. Overall customer satisfaction oriented decision-making process is applied for the alternatives generated from both innovation design process and adaptive design process. The correlation matrix, which affects the weight of criteria, is modified according to the style of broken contradiction for the application of TRIZ. Meanwhile, triangular fuzzy numbers are utilized to deal with vagueness of human thought. Finally, an example is taken to show application of the framework.

Abstract: As a new type of torsional vibration damper, a Dual Mass Flywheel (DMF) has different configuration and working principle from the traditional clutch. Focusing on the problem of matching DMF with a diesel engine, the relationship of circumferential spring dual mass flywheel (CS-DMF) and gearbox is analyzed based on a multi-freedom model, and then the methods of gearbox selection, rotary inertia coefficient ascertain and optimization of torsional stiffness are proposed in this paper. The methods have been applied to a CS-DMF matching with a passenger car with diesel engine. Modal simulation and torque fluctuating experiment show the CS-DMF has excellent damping performance.

Abstract: Optional disassembly could fulfill the process that parts remove from assembly, which is useful for product maintain, discarding and recycle. Total disassembly planning algorithm can be obtained through proper analysis and evaluation, however that is a difficult process. It is hard to obtain optimal solutions when a huge number of parts are to be removed from an assembly. Exponential explosion during the process of disassembly sequence generation has become a bottleneck for a long time due to over large number of parts included in the product. To solve this problem, an approach based on the modulization is proposed in the paper to generate the disassembly sequence. To partition modules of manufacture equipments, the module identifying method based on multi-rule decision can effectively solve the explosive problem. This method deals with the restrictions and limits of parts before disassembly, hence making disassembly more like the situation of the fact which is limiting the quantity of disassembly combinations, enhancing the efficiency of disassembly and making disassembly much easier.

Abstract: In this paper, by introducing the conceptions of stress condition and soft coefficient, a nonlinear equation is used to describe stress condition of the contacting body along depth. By taking the classical contact problem of two parallel cylinders as an example, we give a quantitative description of work-hardening layer’s depth related to local contact problems by using soft coefficient, and it is theoretically proved that plastic deformation and plastic failure exist objectively in engineering contact problem. The analysis indicates that hardening layer’s depth in the range of 0.43643b(where “b” represents contacting semi-width ), where soft coefficient equivalents to infinity, can be defined as "work-hardening surface layer", depth ranging from 0.43643b to 3b can be roughly defined as "subsurface layer", and depth ranging out of 3b can be defined as "deep layer". Finite element analysis of Ono-rolling specimen shows that measuring method of x-ray of the residual stress is relatively more accurate in the surface layer; however, numerical method can give more accurate results than experimental method in the subsurface and deep layer.