Papers by Author: Li Yong Wang

Abstract: The reciprocating machinery has complicated structure, various motion forms and high difficulty of fault diagnosis, now we mainly apply the multi-sensor information fusion as the effective solution. This thesis introduces the structure model of reciprocating machinery information fusion, establishes the tree diagnosis model for fault diagnosis feature information fusion of reciprocating engine, describes the fusion diagnosis steps, and puts forward the technological approaches and methods to solve fault diagnosis information fusion of reciprocating engine from the aspect of testing methods and diagnosis modeling.

Abstract: On the basis of complicated structure, various movement forms and high difficulty of fault detection for reciprocating engine, we have implemented the research on fault diagnostic approach by multi-sensor information, carried out the multi-source information fusion based on crankshaft phase signal, vibration signal, ultrasonic signal, pressure signal, ignition voltage signal and oil analysis information, created distributed structure model with multi-source information fusion, explained the parallel, distributed, serial and tree topology structure models, and established total model for multi-source information fusion of reciprocating engine fault diagnosis.

Abstract: Multi-point forming (MPF) is an advanced flexible manufacturing technology for three-dimensional sheet metal forming. The substance of MPF is replacing the conventional solid dies by a set of discrete punches called punch group. Due to the discrete contacts between the workpiece and punches, the dimple defects occurred, which are inevitable and particular for MPF. In this study, the analysis of the deformation features of the dimple defects was implemented. The dynamic explicit finite element method was chosen to implement the simulation of MPF process. The influencing factors of the surface defects were researched. The relevant experiment was implemented, and it verified that the forming defects decreased with the increasing of the thickness of metal plate and the objective surface curvature radius.

Abstract: Based on characteristics and operating principle of reciprocating machinery, we presented fault diagnosis and data testing method of reciprocating machinery, which features the testing based on crank phase signal, cylinder pressure, temperature, vibration and ultrasonic signal, developed a embedded data acquisition system, and described system composition and module functions. We also realized a CAN bus-based data transmission and communication mode, introduced the slave computer software working flow of the testing system, and developed the data processing and fault analysis software with LABVIEW. The practical tests show that crank phase signal-based data testing can meet requirements on fault diagnosis and data acquisition of reciprocating machinery.

Abstract: This paper discusses disadvantages of existing diagnosis fault system for reciprocating machinery, and based on structural characteristics and operating principle of the reciprocating machinery, it also presents that a portable fault diagnosis system of reciprocating machinery shall be composed of three parts: sensor, data acquisition device and hand-held terminal, in which the data recorder is mainly prSovided for signal conditioning, A/D for data conversion and transmission, and hand-held terminal for data receiving and processing, fault diagnosis, display and storage. The experiment and tests show that this portable fault diagnosis system is feasible for field online monitoring of status and fault diagnosis for reciprocating machinery.

Abstract: Multi-point forming (MPF) is an advanced flexible manufacturing technology for three-dimensional sheet metal forming. The substance of MPF is replacing the conventional solid dies by a set of discrete punches called ‘‘punch group’’. Because the reconfigurable discrete punches are used, part manufacturing costs are reduced and manufacturing time is shortened. However due to the discrete contacts between the workpiece and punches, the dimple defects occurred, which are inevitable and particular for MPF. For thick plate, the surface defect is the mainly dimple defect during its MPF process. In this study, elastic cushion was proposed to prevent these surface defects. The dynamic explicit finite element method was chosen to implement the simulation of MPF process. The Hill’s anisotropic yield criterion was used to describe the workpiece material behavior, and the elastic cushion was described with using the hyperelastic material model. The method to determine each punch position to construct forming surface was introduced. The MPF process with and without using elastic cushion was simulated to study the effect of the elastic cushion on preventing the surface defects. The relevant experiment was implemented, and it verified that the elastic cushion is effective method to suppress the surface defects during the thick plate MPF process. Keyword: flexible forming process (FFP), elastic cushion, surface defects, multi-point forming (MPF), thick plate, numerical simulation

Abstract: Oil spectrum analysis technology is an important method to research wear of mechanism without unpacking, based on the characteristics of limited amount of oil analysis samples and randomness of sample data changes to apply gray theory to prediction of wearing capacity of reciprocating engine. When gray modeling, if sample data does not meet smoothness conditions, firstly parametric process is carried out for the data in order to weaken randomness of the original random sequence, then equal interval process for initial data sequence is conducted and sequence of gray values is determined according to variation rules of sample data, finally, base on four-dimensional data to carry out unequal interval process by timing fitting method. Test confirms that gray modeling by timing fitting methods based on wearing law to determine gray values point can significantly increase prediction accuracy of wearing capacity.