Dissertation > Transportation > Road transport > Automotive Engineering > Automotive structural components > Cab and body > Car body

Dynamic Response and Reliability Analysis of Bus Body

Author ChenYang
Tutor ZhangTianXia
School Northeastern University
Course Vehicle Engineering
Keywords Bus Body ANSYS APDL Modal Harmonic Transient PSD Dynamic Reliability
CLC U463.82
Type Master's thesis
Year 2009
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With the research object of a certain type of bus body framework, this thesis elaborates the basic theory of finite element method (FEM), and investigates the building process of the body finite element model deeply. The three-dimensional data model is established by APDL language in ANSYS software. Through choosing unit types and defining the material properties, meshing grid, handling loads, defining the boundary conditions, the finite element model of the body is finished.First, this thesis carries out a modal analysis for the body framework based on the theory of finite element dynamic analysis using ANSYS, and extracts the former 26-order modal and frequency, in order to lay the foundation for dynamic response analysis. Through the harmonic response analysis, this thesis simulates the impact of the engine vibration excitation on body structure, in order to propose the improvements for the choice of engine operating parameters and design of body structure.Then, this thesis analyzes the transient processes of dynamic reversing and emergency braking, to obtain the response data of displacement and stress time history at the dangerous points. This thesis also carries out a PSD analysis according to the displacement power spectrum of level-B roads, and calculates the statistical distribution of stress and the PSD curves of the displacement, velocity, acceleration at any point, to find the resonance frequency under this road excitation for the improvements of structure design.At last, this paper puts forward a new method for calculating the dynamic reliability of structure. Through combining the PSD analysis with Monte Carlo probability analysis, considering the material properties and the structure parameters, regarding the maximum dynamic stress as the output random variable, it finishes 300 times of sample analysis cycles, to calculate the statistical distribution of the maximum stress and the top 10 most important random variables.This study guides and improves the design of body structure. The results of the analysis can be used to develop new models, effectively shorten the design cycle, and reduce the cost of design。

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