Papers by Author: Hong Peng Li

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Authors: Hong Peng Li, Yu Ting He, Rong Shi, Heng Xi Zhang, Feng Li
Abstract: The mostly working time of airborne electronic equipment is under preliminary depletion failure phase, and inspection & maintenance at intervals can’t lower the failure probability. In this paper, the law of airborne electronic equipment failure is introduced firstly. Then, methods for failure prediction are summarized and analyzed. Finally, an example for predicting the airborne radar failure using the Auto-Regressive (AR) and Support Vector Regression (SVR) model is presented. On this basis, it is possible to achieve the goal that increases the reliability in working phase and establish a more scientific maintenance system and to assure the safety of airborne electronic equipment.
2892
Authors: Yu Ting He, Chao Hua Fan, Heng Xi Zhang, Feng Li, Hong Peng Li
Abstract: To consider the corrosive effects on aircraft structural life under natural environments, we have the calendric life to represent its impact. A new concept of Aircraft Structural Life Envelope (ASLE) to consider the combined effects of fatigue loads and corrosive conditions is developed and the sketch of ASLE is presented, then the basic determining methods of ASLE under different corrosive conditions are obtained too. Finally the linear damage cumulative rules are employed to analyze the usage of aircraft in different corrosive conditions, and the residual fatigue life and calendric life of aircraft structures can be predicted and supervised.
703
Authors: Yu Ting He, Hong Peng Li, Rong Hong Cui, Chao Hua Fan
Abstract: Interfacial delamination is a recognized failure mode in Integrated circuits (ICs). A major cause for this failure is the mismatch of Thermal Expansion Coefficients, Young’s modulus, and Poisson’s ratios of the package materials. Here, the influence of delamination between epoxy and dielectric layers on pattern shift and passivation cracking in IC package under aeronautical conditions, mainly temperature and load cycles, is studied by maximum plastic strain and maximum principal stresses theory using a certain 2D FEM model with different delamination length “L_c.right”. Delaminations are easy to introduce more dangerous impact to the package, because the IC microstructures endure serious thermo-mechanical loading under aeronautical working conditions. The method can be used to find the dangerous designed structure schedules and will provide a basis for selecting passivation materials of aeronautical IC packages.
919
Authors: Xing Jian Wang, Hong Peng Li, Jun Cao
Abstract: Particleboard is a widely used panel material because of its physical properties and low cost, the hot-pressing operation is the one of the most important stages of the whole particleboard production in which many physical processes are involved, such as mat moisture content and distribution, heat transfer. A number of factors are involved including resin type, press temperature, wood species and press closing time, pressure during pressing, Considering coupled heat transfer with resin release ,we presented a mathematical model have been given and solve the modeling with the method of variable separation characteristics and function expansion method. The model has described the relation of center layer temperature changes with pressing times. It is helpful for further research of Internal change in hot-pressing
246
Authors: Yu Ting He, Hong Peng Li, Rong Shi, Feng Li, G.Q. Zhang, L.J. Ernst
Abstract: The passivation cracking of Micro-structures of IC packages is studied by maximum principal stress theory using a certain 2D FEM model with different design parameters, pitch of lines, width of line, thickness of epoxy, thickness of dielectric layer, thickness of glue, the glue material’s yielding stress and Aluminium yielding stress (following as “d”, “w”, “t_epo”, “t_Teos”, “t_glue” “sy_glue” and “sy_al” respectively). For different critical process steps, the final process temperature is acted as a representative parameter to analyze its impact. Furthermore, Response Surface Model (RSM) of principal stress is established using any two design parameters. Results show that “d”, “w”, “t_epo”, “sy_glue” and “sy_al” will have great influence on passivation cracking while “t_Teos” have a little impact.
515
Authors: Yu Ting He, Rong Shi, Hong Peng Li, Feng Li, G.Q. Zhang, L.J. Ernst
Abstract: Pattern shift is one of the main failures of micro-electronics. In this paper, the influence of plastic deformation values of micro-structures of IC packages on the pattern shift of metal lines is studied by maximum plastic strain theory using a certain 2D FEM model with different design parameters, “d”, “w”, “t_epo”, “t_Teos”, “t_glue” “sy_glue” and “sy_al”. For different critical process step, the final process temperature is acted as a representative parameter to analyze its impact. Furthermore, Response Surface Model (RSM) of plastic strains is established using any two design parameters. Results show that “w”, “t_epo”, “t_Teos”, “t_glue” “sy_glue” and “sy_al” will have different influence on pattern shifting while “d” have little impact.
1333
Authors: Chao Hua Fan, Yu Ting He, Hong Peng Li, Feng Li
Abstract: Genetic algorithm is introduced in the study of network authority values of BP neural network, and a GA-NN algorithm is established. Based on this genetic algorithm-neural network method, a predictive model for fatigue performances of the pre-corroded aluminum alloys under a varied corrosion environmental spectrum was developed by means of training from the testing dada. At the same time, a fuzzy-neural network method is established for the same purpose. The results indicate that genetic algorithm-neural network and fuzzy-neural network can both be employed to predict the underlying fatigue performances of the pre-corroded aluminum alloy precisely.
1283
Authors: Chao Hua Fan, Yu Ting He, Heng Xi Zhang, Hong Peng Li, Feng Li
Abstract: In the paper, genetic algorithm is introduced in the study of network authority values of BP neural network, and a GA-NN algorithm is established. Based on this genetic algorithm-neural network method, a predictive model for fatigue performances of the pre-corroded aluminum alloys under a varied corrosion environmental spectrum was developed by means of training from the testing dada, and the fatigue performances of pre-corroded aluminum alloys can be predicted. The results indicate that genetic algorithm-neural network algorithm can be employed to predict the underlying fatigue performances of the pre-corroded aluminum alloy precisely, compared with traditional neural network.
1029
Authors: Yu Ting He, Feng Li, Rong Hong Cui, Chao Hua Fan, Hong Peng Li
Abstract: When studying the growth of triaxial-stress-state crack, the plastic work rate consumed in the process zone at crack tip should be described clearly. Fracture for a cracked specimen is related to rupture of a simple uniaxial tensile specimen by nature. By equaling the crack tip stress-strain field to uniaxial stress-strain field, it is obtained that the plastic work rate consumed in the process zone at crack tip can be expressed by the plastic energy density WF multiplied by the equivalent size of the process zone hF. The plastic energy density WF can be expressed by virtue of uniaxial true stress-strain curve. And analytical form of hF for triaxial stress state is presented by recourse to three-dimensional analyses on material behaviors. The expression of plastic work rate consumed in the process zone is verified by the predicting fracture toughness.
19
Authors: Hong Peng Li, Yu Ting He, Heng Xi Zhang, Rong Hong Cui
Abstract: This paper presents our effort to reduce thermo-mechanical failures related IC packaging reliability problems. These reliability problems are driven by the mismatch between the different material properties. First of all, finite element analysis are adopted to investigate the influence of encapsulation structures and material properties on the stress distribution in dielectric layers and plastic strain distribution in die for a typical stacked package of IC microstructures. Results show that thinner package body, lower thermal stress and smaller plastic strain can be realized in this micro-structure with the different design geometry parameters and materials properties. Secondly, it was also found that the transition layer of TiN between the die and dielectric layer has a pronounced influence on decreasing the local stress in the passivation layer by comparison analysis. These studies would be beneficial to improve the reliability of stacked IC micro-structure packages.
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