Dynamic FEM Analysis of Automobile and Software Development

In this article, modal analysis technology about dynamic analysis was studied. Free interface model comprehensive method was used to dynamic analysis and design of automobile structure based on theory background of model analysis, test technology conditions, data reliability and precision. In order to test the efficient and possibility of the method, main vibration features about space double layer has been calculated based on this method, comparing this with the precise solution of finite element method, the result shows that this method is suitable not only for simple interfaces between components but also for high reductive interfaces. In addition, the method also has high comprehensive precision. Furthermore it creates conditions to dynamic analysis in automobile structures.     

Influence of Location and Form of HE-charges on the Air Blast Pressure Inside the Tunnel

In order to understand clearly to the influence of location and form of HE-charges on the air blast pressure inside the tunnel, based on Hopkinson scaling law, attenuation of air blast peak pressures in long tunnels due to HE-detonations in the case of different location and form at the tunnel entrance is simulated with the dynamic finite element software of LS-DYNA. The results are compared with other experimental methods. The results indicate that the influence of location and form of HE-charges is significant near the HE-charges. As the distance from the HE-charges larger and larger, the influence of location of HE-charges is smaller and smaller, but the influence of form of HE-charges is larger and larger. The methods and data presented can be refereed in similar engineering and determination of loadings upon protective doors.     

Experiment Analysis on Noise of the Minibus Exhaust Muffler

On the basis of analysis and research on an automobile exhaust noise, the theory and test combination method was adopted to improve the muffler, and then the acoustics performance of muffler was validated by doing some experiments with the engine. On different speeds of the engine, the inserting loss and spectrum characteristic under several muffler methods were studied. Finally the best muffler method was confirmed, and the purpose of reserving was achieved.     

Numerical Analysis of Acoustic Environment with Finite Element Method

The acoustic environment of highway tunnel is complex and has influences on the driving safety and comfort. In case of emergency, evacuation information is difficult to transfer. Finite element method is used for calculating highway tunnel acoustic modal and attenuation characteristics. The results show that acoustic mode of highway tunnel has symmetry in the horizontal pressure amplitude of symmetry regional is equal and phase is the same or opposite. The higher modal frequency, the greater sound pressure amplitude is, and the effect of tunnel length on modal frequency is smaller. Decay curves of pressure level at each point in the highway tunnel over time are nonlinear. After the source excitation, in 1.5 s, attenuation rate is faster than that of few seconds later and the attenuation time of sound pressure level 30 dB is 5.5 to 7 s.     

Acoustics simulation and structure optimization of a motorcar exhaust muffler

Aiming at the exhaust muffler of a 244S motorcar, the acoustics field model and the flow field model are established by adopting Finite Element Method. The 3-D acoustic simulation is carried out by using software SYSNOISE, and an improvement scheme with optimized inner structure of the muffler is proposed based on the simulation. The acoustic simulation result and the bench test result of the improved muffler show that the muffling ability in middle and high-frequency of the improved structure is obviously stronger than the original structure, and the simulation result coincides well with the bench test result. Meanwhile, the flow field simulation result shows the power loss of the engine has little change, which means that the structure improvement of the original muffler is effective.     

Analysis of Numerical Simulation of Seepage Failure and Seepage Feature of Seawall

In order to analyze seepage feature and seepage failure mechanisms of seawall under flood infiltration, a numerical model for saturated-unsaturated and unsteady seepage flow analysis considering soil permeability variation with seepage failure process was established. And the corresponding finite element computation program was made. Numerical simulation of flood seepage for typical section of real seawall was carried out by use of the program. The computed results were compared with the measured results of field test, which shows good agreement. Based on the numerical simulation results, it can be seen that flood seepage of seawall is a saturated-unsaturated and unsteady seepage flow process and seepage failure of seawall is caused by long time flood infiltration under large seepage gradient. Therefore, upon the flood infiltration, seepage failure of the seawall is a very complicated process, which involves soil permeability variation with seepage failure process and saturated-unsaturated/unsteady seepage flow. It is questionable to use the steady seepage analysis method to simulate seepage failure process of seawall.     

Numerical simulation of dynamic response and radiation noise of gearbox

Considering the internal dynamic excitation produced by stiffness excitation, error excitation and mesh impact excitation, a dynamic finite element model of transmission system and structure system of gearbox is established. The normal mode and the dynamic responses of gearbox under the internal dynamic excitation are calculated by using the numerical simulation software ANSYS. Based on the result of dynamic responses, the boundary excitation condition is determined, and then the acoustic boundary element model is built. With the software of SYSNOISE, the surface acoustic pressure of gearbox and the radiation noise of field points are solved by the direct boundary element method. The test of airborne noise is carried out. The computational results obtained are in a good agreement with the data of experimental test.     

Numerical Analysis on Stability of Rock in Sijiaotian Tunnel

The Sijiaotian Tunnel in Yunnan Dabao Highway lies in the narrow defile landscape,and the engineering geology condition is complex,with plenty of cienega.According to the actual situation of the Sijiaotian Tunnel Project in Yunnan Dabao Highway,the stability of the surrounding rock mass is studied by using a 3-D non-linear FEM.The Drucker-Prager criterion is chosen as the failure criterion of the rock.The relatively dangerous zone and the monitoring points in the tunnel are determined.The numerical results show that the Sijiaotian Tunnel is relatively stable.The conclusion has some significance for guiding the construction of similar projects.     

Application of Magnetic Analysis in Magneto-rheological Damper Performance Estimation

As a kind of semi-active controllable devices,Magneto-rheological(MR) damper has been increasingly widely used in various occasions of vibration suppression.However,the design of MR damper greatly depends on the engineering experience of designers,it is difficult to calculate the performances relatively accurate.With the Finite Element Method,the authors carry out the magnetic analysis on the given geometry of MR damper combined with the Couette flow analysis of MR damper,the dynamic curve of MR damper is obtained.The results show that the FEM magnetic analysis effectively predicts the yield shear force and flow shear force,it is coincident with the experimental data.It is validated that the methods described is suitable for the MR damper performance estimation of the same geometry,and is an effective means for the MR damper design with the given force.     

Object-oriented Design of Three-Dimensional Numerical Manifold Method

The Object-Oriented technology is introduced into the 3-d Numerical Manifold method(NMM). The design method and management of the Classes about the three dimensional Numerical Manifold Method are studied. The Classes are designed and the prototypes of some key classes are shown. As an example,the 3-d numerical calculation results are given. The calculation results are in good agreement with the theoretical solutions. It shows that the Object-Oriented programming of 3-d NMM is correct.     

Finite Element Analysis of Masonry RVE Homogenization Procedure

Homogenization is one of the most important steps in the numerical analysis of masonry structure, where the continuum is used. A masonry representative volume element (RVE) is formed as the equivalent element of masonry components and it is the most important step in homogenization procedure. The RVE is molded with consideration of the material properties of mortar and brick as well as their interaction separately. In this paper the masonry RVE is simulated with the finite element software ANSYS. The stress-strain relationships of RVE subjected to different types of loading conditions are presented. The equivalent elastic modulus and Poisson's ratio are calculated and the feasibility of finite element method used in the procedure of masonry homogenization is demonstrated.     

Elastic Analysis of Beam-Plate Foundation with Winkler Model

The beam-plate foundation is divided into two parts.The boundary element methods areapplied to analyze the plates with Winklermodel.The finite element methods are used to evaluate thebeams The coupling equation is obtained by the coodination of both force and displacement.     

Experimental Analysis on Seismic Performance of Steel Bracing Bound-Column Component

The seismic resistant performance and failure mechanism of the steel bracing Bound-Column were analyzed with tests and the finite element method. Two-story steel bracing Bound-Column test specimen was selected. The braces adopt long leg back-back double angle. Tests were divided into three groups, including one monotonic loading test and two cyclic tests. Lateral load-bearing capacity, stiffness and hysteretic behavior of the steel bracing Bound-Column were obtained by the comparison of test results and the finite element method. Results show that the steel brace of Bound-Column contributes a lot to its load capacity and stiffness, while the external frame provides little lateral rigidity and capacity. Bound-Column failure occurs only in the steel braces, while the external frame is with no damage.     

Flow Field of High-temperature Gases and Exhaust Hood Optimization in Ironmaking Plant

Large amounts of high-temperature gases were generated in ironmaking plant and ideal acceptable hood above the heat source was not installed affected by process conditions. At the top of the exhaust hood, dust easily escaped because of thermal plume.Based on the test data of dust composition and size distribution in ironmaking plant, numerical models suitable for high-temperature dust gases were established and key boundary conditions for the gas-solid two-phase flow under high-temperature conditions were determined.The study shows velocity decay of convergence field is sharp at the suction outlet and thermal plume is strong in the exhaust hood. The control method of pressure distribution and the key factor to prevent high-temperature dust escaping are proposed in the exhaust hood. Optimized design and engineering practice of the exhaust hood are given when the suction outlet is on the side after analyzing the flow field resulted from coupling effect of thermal plume and ventilation airflow.     

Numerical Simulation of Groundwater Flow and Quality

With societal development, wastes exist in industry, agriculture and human life. In particular, a large volume of urban industrial sewage is discharged and pesticides and fertilizers are widely used, leading to groundwater pollution in many areas. Based on a water quality model of hydrodynamic dispersion and the multi element balance (MEB) method, a general program for simulating groundwater flow and quality is carried out using the program VC++ for visual presentation. Using this program in a case study, the transportation mechanism of groundwater flow and quality is simulated numerically. The result indicates that the program is visual and can be manipulated well. It offers a point of reference for the reasonable exploitation, protection and utilization of the groundwater.