Modeling Method of Automotive Body CAN/LIN Nets Application Protocol Based on Object-oriented Colored Petri Net

Recently automotive nets are adopted to solve increasing problems in automotive electronic systems.Technologies of automotive local area network from CAN and LIN can solve the problems of the increasing of wire bunch weight and lack in module installation space.However,the multilayer automotive nets software becomes more and more complex,and the development expense is difficult to predict and to keep in check.In this paper,the modeling method of hierarchical automotive nets and the substitution operation based on object-oriented colored Petri net(OOCPN) are proposed.The OOCPN model which analyzes the software structure and validates the collision mechanism of CAN/LIN bus can speed the automobile system development.First,the subsystems are divided and modeled by object-oriented Petri net(OOPN).According to the sets of message sharing relations,the message ports among them are set and the communication gate transitions are defined.Second,the OOPN model is substituted step by step until the inner objects in the automotive body control modules(BCM) are indivisible and colored by colored Petri net(CPN).And the color subsets mark the node messages for the collision mechanism.Third,the OOCPN model of the automotive body CAN/LIN nets is assembled,which keeps the message sets and the system can be expanded.The proposed model is used to analyze features of information sharing among the objects,and it is also used to describe each subsystem real-time behavior of processing messages and implemental device controllers operating,and puts forward a reasonable software framework for the automotive body control subsystem.The research can help to design the communication model in the automotive body system effectively and provide a convenient and rapid way for developing the logical hierarchy software.

Effect of Welding Seam Spacing and Relative Bar Wall Thickness of Bus Framework on Joint’s Local Mechanical Property

Now the researches concerning integral bus mainly focused on design and analysis of overall mechanical property of bus body, and paid little attention to characteristic of local structures, such as joint, plug welding hole, and bolt connection point, etc. So there is much blindness on the design of local connecting structure. Since integral bus body structure cancels large section longitudinal beam, and uses framework made by welding small section bars together as principal part to bear the whole load when the vehicle works, there are many joints receiving high load in the body structure, and local stress concentration can not be avoided. Under such circumstances, by adopting beam-shell mixed model based on super element technique, and selecting a joint commonly used by bus sidewall, the rule of the effect of bar joint’s welding seam spacing on joint’s local mechanical property is investigated in this paper, and the investigating results show that joints have minimum stress concentration with welding seam spacing of 8 mm. To learn whether the above rule is affected by relative bar wall thickness, many groups of bars with different relative bar wall thicknesses are studied experimentally, and the experimental results show that the joints local stress levels vary with different relative bar wall thicknesses, but the rule of the effect of bar joint’s welding seam spacing on joint’s local stress level remains the same. The research is significant for local structure design of bus joint in the future.

Multi-objective Collaborative Optimization for the Lightweight Design of an Electric Bus Body Frame

To analyze the rollover safety,finite element models were established for the electric bus body frame,rollover simulation platform,living space,and bus rollover.The strength and stiffness of the body frame were calculated under four typical work-ing conditions considering the main low-order elastic modal characteristics.The results indicate that the initial body frame of the electric bus satisfies the required structural strength,stiffness,modes,and rollover safety,and it has great potential for lightweight design.Sensitivity and structural contribution analyses were performed to determine the design variables for lightweight optimization of the body frame,and a mathematical model was established for multi-objective collaborative optimization design of the electric bus.Then,the radial basis function neural network was used to approximate the optimiza-tion model.Besides,the accuracy of the approximate model was verified,and the non-dominated sorting genetic algorithm II was employed to determine solutions for the lightweight optimization.Compared with the initial model,the mass of the optimized model is reduced by 240 kg(9.0%)without any changes in the materials of the body frame.