Full-load bus body optimized structure design and analysis

Full–load bus body optimized structure design and analysis

Abstract: The body structure for vehicle performance plays an important role, so the body structure design of the study very important. At present the overall level of China’s passenger car industry greatly improved the quality of passenger vehicle has also been developing steadily, but with the international advanced passenger car industry, they are still there is a big gap. The modern industrial development in an important direction for passenger carrying bus body to start the whole carried out a structural analysis and optimal design.

Keywords:: full load; body structure; optimization; Bus A full-load bus body structure optimization design method

(1) changing the type of material, using low density, Young’s model of high value materials.

(2) changing the cross-sectional beam shape of the body to improve cross-section of the torsional and bending rigidity.

(3) a change in the thickness of the main structural parts, making the structure to enhance the overall performance. Beam structure by changing the body shape and thickness of the cross-section is the most suitable host body-wide optimization design methods to improve the cross-section torsional, bending rigidity, but also to achieve lightweight body.

(4) Body frame solder joint deal with. Body skeleton structure has more than the number of solder joints (usually tens of thousands of thousands of one), with space for more complex surfaces and geometric characteristics and other characteristics, subject to hardware constraints of the body to establish a precise model is extremely difficult. According to solder joint force characteristics, domestic and foreign literature has proposed several simulation methods, see Table 1:

From Table 1 we can see a single solder joint, if a high degree of block with the appropriate element simulation, the availability of high precision, but it will take a very close local grid. A large number of uniform, dense arrangement of the solder joints, an appropriate adjustment solder thickness and material parameters area, you can use simulation and modeling of single-layer plate and high efficiency. To simulate spot welding zone adjacent to the local component in the vibration isolation and exposure, then the node can be a more appropriate legal trouble.

2 full-load bus body structure optimization design of beam

2.1 Structure of Sensitivity Analysis Algorithm Sensitivity is a broad concept, from the mathematical sense, can be interpreted as: If the function F (x) can be guided, first-order sensitivity can be expressed as:

The analysis of the structure can be divided into dynamic analysis and static analysis of two aspects of the structure of the corresponding sensitivity analysis can be divided into dynamic and static sensitivity analysis. Dynamic sensitivity analysis has features (characteristic values, characteristic vectors) sensitivity analysis, transfer function, sensitivity analysis and dynamic response sensitivity analysis, etc.; static sensitivity analysis can be displacement, stress and so on.

In the finite element linear static optimization analysis, the constraints and objective function are likely to be static equilibrium equation of the response displacement solution, denoted by T = T (δ ). The displacement is an implicit function of design variables, denoted by δ = δ (X) is: T = T (δ (X)). Available displacement sensitivity of design variables as follows:

As can be seen from the above formula, changes in structural parameters Xj a direct impact on the quality of matrix M and stiffness matrix K, and then change the natural frequency.

In order to weigh each variable in a design to increase or not affect or improve the dynamic performance of the stiffness while reducing body mass, defines a measure of R, in order to cross-section thickness on the impact of body mass and stiffness compared, for example, the calculation formula as follows:

R value is increased when the cross-section X s mm thickness when its vehicle quality, vehicle stiffness and an increase in the ratio of the contribution.

2.2 Sensitivity Analysis of Body

As the front axle and rear axle right wheel and right wheel vacant vacant condition before and after the cars were to shift significantly lower than the bending condition, so discuss the vehicle body torsional stiffness of the frame beam (rectangular profile) long a, width b, thickness t, sensitivity, while the quality of the design parameters for calculating vehicle sensitivity, and calculate R values. Component parts according to the type, location and role of selecting a number of important components to carry out sensitivity analysis. Table 2 lists the specific names and code components.

Location of the name of spare parts for sensitivity analysis the main roof beams (A0 ~ A20), the main longitudinal beam (A21 ~ A24) pre-Wai front windshield pillars (B1 ~ B2), the windscreen of the beams (B3 ~ B4) after the post-Wai windshield column (B6 ~ B7), after the windscreen beam (B8 ~ B9) sidewall side window glass column (C1 ~ C18), waist beam (C19 ~ C22), the door column (C23 ~ C38) drivers to monoblock Main Longitudinal (E1 ~ E6), with the former junction of the main bridge beams (E7) Center for the floor the pedal before the car beam (F1 ~ F8), the upper center main beam (F5 ~ F6) pedal after the car before the floor beams (G1 ~ G4) , with hinged front plate connected to beam (G5 ~ G7) before, during and after beam axle air spring constraints (H1 ~ H20), axle carling (H21 ~ H26), with the center engine support floor keel stringer (I1 ~ I2), support the transmission beams (I3 ~ 8), water tanks suspension beams (I9 ~ 11) after the front compartment open front door pillars (J1 ~ J4) sensitivity analysis, changes in all parameters set the range of 130%, in this within the iterative interpolation. As the front and rear axle to reverse the car only on the torsional stiffness of their own car has obvious implications, were calculated before and after the train frequency and an order to reverse the bridge, took place after the bridge turn around the car when the body torsional stiffness of the beam element sensitivity. Reposted elsewhere in the paper for free download

2.3 Optimal Design

According to the results of sensitivity analysis to choose the right lightweight impact of the more obvious parameters, as shown in Table 3, with sensitivity analysis, set all the parameters range of ± 35%, the objective function of the quality of the smallest, respectively, a first-order vehicle to reverse the frequency