Study on the static properties of spiral springs under static loading

Applied Mathematics and Mechanics - Spiral springs have a wide range of applications in various fields. As a result of the complexity of friction, few theoretical analyses of spring belts under...     

The numerical method for three-dimensional impact with friction of multi-rigid-body system

The differential equations for planar impacts reduce to an algebraic form, and can be easily solved. For three dimensional impacts with friction, there is no closed-form solution, and numerical integration is required due to the swerve behavior of tangential impulse during collisions. The dynamic governing equations in the impact process are built up in impulse space based on the Lagrangian equation in this paper. The coefficient of restitution defined by Poisson is used as the condition of impact termination. A valid numerical method for solving three-dimensional frictional impact of multi-rigid body system is established. The singular cases of tangential movement in sticking point are especially noticed and analyzed. Several examples are present to reveal the different kinds of tangential movement modes varied with the normal impulse during collision.     

IMPACT MODEL RESOLUTION ON PAINLEVE’S PARADOX

Painlevé‘s paradox is one of the basic difficulties for solving LCP of dynamic systems subjected to unilateral constraints. A bi-nonlinear parameterized impact model, consistent with dynamic principles and experimental results, is established on the localized and quasi-static impact model theory. Numerical simulations are carried out on the dynamic motion of Painlevé‘s example. The results confirm ““““impact without collision““““ in the inconsistent states of the system. A ““““critical normal force““““ which brings an important effect on the future movement of the system in the indeterminate states is found. After the motion pattern for the impact process is obtained from numerical results, a rule of the velocity‘s jump that incorporates the tangential impact process is deduced by using an approximate impulse theory and the coefficient of restitution defined by Stronge. The results of the jump rule are quite precise if the system rigidity is big enough.     

考虑刚弹耦合作用的柔性多体连续系统动力学建模

基于Ｈａｍｉｌｔｏｎ原理建立起一般柔性体连续系统的动力学建模方法,进而以水平面内作大范围回转运动的柔性梁为例,在Ｅｕｌｅｒ－Ｂｅｒｎｏｕｌｌｉ梁模型的假设前提下,根据轴向不可伸长的柔性梁的几何约束条件;推导出作大范围刚体运动的柔性梁连续系统的一致线性化振动微分方程．采用假设模态法对其离散化,导出考虑刚弹耦合作用的柔性梁有限维离散化动力学模型．最后给出仿真算例,验证了该方法的有效性．     

Dissolution of uranium dioxide powder in carbonate-peroxide solution

Journal of Radioanalytical and Nuclear Chemistry - The effects of different dissolution parameters (solid–liquid ratio, peroxide concentration, carbonate concentration, countercation and pH)...     

Simulation and experimental studies of a vibro-impact capsule system driven by an external magnetic field

This paper studies the electromagnetic field used for driving a vibro-impact capsule prototype for small bowel endoscopy. Mathematical models of the electromagnetic field and the capsule system are introduced, and analytical solution of the magnetic force applied on the capsule is derived and verified by experiment. The impact force between the inner mass of the capsule and the capsule body is also compared via numerical simulation and experimental testing. By comparing the capsule’s progressions under different control parameters (e.g. the excitation frequency and duty cycle), the merits of using the vibro-impact propulsion are revealed. Based on the experimental results, the optimised speed of the prototype can achieve up to 3.85 mm/s. It is therefore that the potential feasibility of using the external electromagnetic field for propelling the vibro-impact capsule system is validated.

     

THEORETICAL ANALYSIS AND EXPERIMETNAL VERIFICATION FOR PAINLEV碋 PARADOX

含摩擦的多体系统可能存在Painlevé 疑难奇异性-- 多体系统的后续运动可能存在无解(非协调状态)或者多解(不确定状态). 实际系统总要运动下去, 而对应于非协调奇异性状态的多体系统将经历怎样的运动值得探讨. 从计算、实验和理论证明3 个角度研究Painlevé 疑难问题, 验证和证明了多体系统处于非协调状态时其后续运动的切向冲击特征, 并揭示了切向冲击运动的共同规律.     

Extraction and separation performance of rhenium(VII) and uranium(VI) from nitric acid medium using N,N′-dimethyl-N,N′-dioctyldiglycolamide

Journal of Radioanalytical and Nuclear Chemistry - The extraction behavior and separation performance of Re(VII) and U(VI) from the nitric acid medium were studied respectively, in which an...