系泊系统耦合动力分析不同解法的比较研究

Newmark-β迭代法和Adams-Moulton法是系泊系统耦合动力分析中广泛使用的两种求解方法.文中运用这两种方法对系泊线进行动力分析,在验证了算法可靠性基础上,分析了两种方法在计算稳定性和效率方面的差异.结果发现:对系泊系统这两种算法拥有相似的计算精度,其中Newmark-β迭代法能适应较大的时间步长,稳定性更好;而Adams-Moulton法的计算效率随时间步长的增大提高很快,但增大步长Newmark-β迭代法的计算效率影响不大.     

Nonlinear free vibration analysis of thin-walled curved beam with non-symmetric open cross section

A finite element formulation was presented for the nonlinear free vibration of thin-walled curved beams with non-symmetric open across section. The kinetic and potential energies were derived by the virtual principle. The energy function includes the effect of fiexural-torsional coupling, the torsion warping and the shear centre location. For finite element analysis, cubic polynomials were utilized as the shape functions of the two nodal thin-walled curved elements. Each node possesses seven degrees freedom including the warping degree of freedom. The nonlinear eigenvalue problem was solved by the direct iteration technique. The results are compared with those for straight beams as available in the literature. The results for nonlinear free vibration analysis of curved beams for various radii and subtended angle are presented.     

Investigation of Occupant Lower Extremity Injures under Various Overlap Frontal Crashes

Objective

With widely usage of restraint system, fatal injuries to occupants have been largely limited while non-fatal lower extremity injuries have not been effectively improved. The present study aims to investigate occupant lower extremity injuries under realistic impact environments.

Methods

A biofidelic lower extremity model, a dummy model and a car cab model were combined to set up a realistic impact environment. Three typical frontal impact groups were simulated. Occupant global lower kinematics, long bone axial force and bending moment were presented to in-depth investigate lower extremity injury mechanism and tolerance.

Results

Various overlap frontal impacts cause totally different lower extremity kinematics in the combination of structural invasion and restraint system effects. The femur fracture occurred at a small axial force of 7.57 kN combing a substantial bending moment peak of 172 Nm. Ankle joint injuries were found in 100 % and 25 % overlap impacts that present large tibial axial force and joint rotation angle.

Conclusions

Overall results indicate that a coupling threshold of femur axial force and bending moment is of rationality to predict global femur fracture. The ankle joint injury occurrence is significantly related to the coupling effects of tibia axial force and excessive self-kinematics.

     

大跨度钢管混凝土拱桥拱肋吊装过程仿真分析

大跨度钢管混凝土拱桥的拱肋吊装是一个复杂的过程 ,为了保证最终的成桥线形和受力状态满足设计要求 ,需要采用施工控制仿真计算。本文给出了仿真计算的具体步骤 ,提出了基于迭代理论的前进分析方法 ,并通过实例验证了此方法的可行性     

船舶防污染机电一体化仿真系统

本文介绍了新开发的船舶防污仿真系统.该系统按照机电一体化的仿真思路,将电气控制界面和机械管路界面相结合,涵盖了船舶防污系统中主要的机械设备和电气设备控制电路,对于培养机电一体的新型船舶管理人员和航海类专业学生有重要意义.该系统已经应用在教学和船员培训中,并取得了良好的效果.