Fang Zhen Song

Vibration Sensitivity Analysis of the Secondary Isolation Support

The second vibration isolation support (SVIS) is very important parts of the vibration engineering equipment, and its dynamic performance will affect the operating condition of the entire device. In the design process, the sensitivity of design parameters provides a very effective way for design of SVIS. By analyzing the sensitivity of the amplitude of SVIS relative to the mass of SVIS, the spring stiffness and the operating frequency, as well as the sensitivity of the modal natural frequency relative to the plate thickness, the influence degree of these design parameters on the dynamic characteristics of SVIS were obtained and the best optimization parameters the structure of SVIS were obtained.

The Finite Element Analysis of Vibrating Screen

The large-scale and modular design of vibrating screen brings about the trend that the screen separate from screen frame. The separation of the screen frame and the screen changes their dynamic characteristics. By making modal analysis and harmonic response analysis in ANSYS, the dynamic data of the screen and the screen frame was obtained, such as the natural frequencies, mode shapes, stress distribution and strain distribution. The results show that the stiffness of screen frame is higher than stiffness of the screen and the side plats and beams of screen are the weak parts.

Lightweight Research of Cabin Structure Based on Response Surface Method

The selection, fitting and evaluation methods of response surface functions are expounded. The parameter sensitivity analysis of the cabin is carried out. The response surface functions of the stress and the vibration frequencies are constructed through the Box-Behnken experimental design method. Fitting inspection on the response surface functions is done with correlation coefficient, correction coefficient, etc. The results show that the response surface models are very similar to the real models. Four design variables are extracted randomly as the test sample of each response surface function. The data gotten by the response surface function are compared with the data gotten by the finite element analysis. The results show that the response surface models are with high accuracy and can reflect the real test values well. These response surface models can be used for further optimization design. They are helpful in reducing the ship mass without exceeding the allowable stress and resonance.

Single Objective Optimization Research of a Bulk Carrier Structure

The purpose to optimize the ship structure is to obtain the minimum weight and the maximization of economic benefit. The way is to change the ship size, structure form, whole or partial structure layout under the condition of meeting the requirements of mechanical properties. The whole ship structure optimization model is established. Optimization is carried out by means of the Optimtoolbox in MATLAB, with the total mass of the ship as objective function, the requirements of the specification and the natural frequencies as constraint conditions. With sensitivity analysis,the thickness of bottom plate, deck, keelson, side keelson, superstructure bulkhead, hatch coaming and other components are selected as design variables. The results show that through optimization, better ship lightweight effect is obtained under the premise of guarantee hull structure strength, stiffness and dynamic characteristics. The bulk carrier structure is optimizaed.

Ship Performance Research Based on BP Neural Network

The problem is solved that it is hard to provide analysis formulas about the maximum equivalent stress, the maximum shear stress and the structural geometric parameters for a ship. The finite element calculation is done with orthogonal experimental design under the most dangerous case. The data obtained are used as the training and test samples to establish BP neural network models of ship’s maximum equivalent stress and maximum shear stress. With the aid of Neural network toolbox in MATLAB, the topological structure of BP neural network mapping relationship between the whole ship performance indexes and design variables is established. The training and testing are completed with the data tested by the shipyard and the correctness of this network is verified. The neural network required for further optimization design is obtained. The neural network is helpful in reducing the ship mass without exceeding the allowable stress.

Sequential Quadratic Programming Method of Cabin Optimization

The basic principle of sequential quadratic programming method and the concrete implementation steps in MATLAB are expounded. Sequential quadratic programming method is used for the cabin structure optimization. In the optimization, the minimal sizes of components stipulated by the rules are used as size constraints, the frequencies required by the rules are used as performance constraints and the minimum lightness of the ship are used as objective. Finite element analysis of the ship structure optimized is done and the results obtained show that both the maximum equivalent stress and the maximum shear stress meet the requirements and first three order frequencies of the cabin structure are also far away from the working frequency of propeller and host. The optimization reduces the weight of the cabin under the condition of meet the static characteristic and dynamic characteristic.

Static and Dynamic Finite Element Analysis of the Whole Ship Structural of Inland Waterway Bulk Carrier

For the chase tank and large opening forms of inland waterway bulk carrier, using finite element method, the whole ship finite element model is established, the total intensity strength of the overall structure is conducted an evaluation study, the stress and strain distribution of the whole ship is obtained. The calculation methods of the entrained water quality is studied, and the entrained water quality is calculated by the method of Lewis and Todd, on this basis, the dynamic characteristics of the whole ship are calculated, the vibration characteristic of the whole ship is got, data is provided the support For the study of the important parts of inland waterway bulk carrier, and it is provided a certain reference for the design studies of inland waterway bulk carriers.

Motion Planning of a Nonholomonic Mobile Manipulator for Moving Object Grasping

This paper studies a nonholonomic mobile manipulator that consists of a wheeled mobile platform with a mounted serial manipulator. It is designed and developed to navigate autonomously in handling moving objects subjected to nonholonomic constraints. A camera is mounted on the front of the platform and employed to identify and collect information about distance, velocity and direction of the object. With that information collected, a motion planning system determines the preferred operation region and the obstacle-avoidance area, and thus generates the expected trajectory of the mobile manipulator. Experimental results are shown that the mobile manipulator can identify the target, generate trajectories and grasp the moving object autonomously.

Finite Element Analysis of Bullet Penetration Circular Sandwich Plate

A nonlinear dynamic finite element method based on ANSYS/LS-DYNA is used to simulate the physical process of a bullet penetrating circular sandwich plate at a speed of about 400 m/s. In the simulation, Lagrange algorithm, Johnson-Cook and Crushable-foam constitutive model are choosed. Energy time history curve, impact force time history curve, Von-Mises stress nephogram and displacement nephogram are obtained. At the same time, stress time history curve of the maximum stress element and displacement time history curve of the maximum displacement node are obtained. Compared with the non-sandwich plate, it is found that the use of sandwich plate can reduce the total mass, inner plate stress and displacement, and can protect inner plate well.

The Frequency Veering Phenomena of the Beams of Cantilever Screen

The special structure of beams of cantilever screen has the advantages comparing with the traditional screen and special dynamic characteristics, such as the dynamic characteristics of frequency veering. The traditional analysis method of vibrating screen is not applicable to its dynamic analysis because of the special structure. By analysis and decomposition of stiffness matrix of beams of cantilever screen, the frequency veering phenomenon of the beam of cantilever screen was explained from the point of view of modal energy equation and the influence of sub-stiffness matrix of beams of cantilever screen on the frequency veering was analyzed. The analysis results showed that the sub-stiffness matrix of the hollow beam and sub-stiffness matrix of cantilever bars is the main reason for the segmentation of modal natural frequencies and the coupling stiffness between hollow beam and cantilever bars is the main reason for the concentration of modal natural frequencies and the formation of the regular mode shapes for cantilever bars group.