Applied Mechanics and Materials Vols. 488-489

Abstract: With the development of industrialization,water pollution is becoming more and more serious,fresh water supplying is becoming more and more inadequate.Some specialists have already researched the methods and developed new equipments which can extract water from air,but considering the large size and weight, the equipments were not convenient carry for field drinking by people.To overcome the shortcomings, the portable photoelectric water extraction device from air is studied, it consists of four parts,there are solar energy supply system, control system, refrigeration system and purification system.The device adapts the advanced method by the solar energy refrigeration to dew, it has four folding solar panels to get the energy and two shells which size could be changed along a slider and fixed by pins.Therefore, the new device has some advantages such as high refrigeration coefficient, high water intake rate, continuous operation long time without sunshine and excellent portability.

Abstract: Based on the multiphase model of FLUENT 6.3,a underwater projectile cavitation model is established for a new designed underwater projectile which have a disc cavitator.Then the cavitation number influence on cavitation form is concerned and contrast with the empirical formula of cavitation form.The conclusion is：with the increase of cavitation number,the drag coefficient will increase non-linear;the cavitation slenderness radio is greater,the drag coefficient is smaller. Supercavitation phenomenon is that when a object moves in water and it’s speed increases constantly, according to Bernoulli's equation, this will make the hydrostatic pressure that it bears drop. And when the pressure down to the vaporization pressure of water at that temperature, the surface moisture of the object will change into steam, form bubbles and wrap it. Due to the density of water and steam has magnitude deviation, the viscous resistance acting on the underwater moving object will reduce greatly, that can make the performance of underwater weapon enhance markedly. In the military applications, there are represented by Russia, the torpedo of “snowstorm” used the ventilation supercavitation theory and, represented by USA, the “20mm Supercavitation projectile” used the nature supercavitation theory. Facing the daily intelligentized contrail guided torpedo and mine, the small caliber supercavitation projectile technology has provided a new method for the short-range defense of surface vessel. As the nature supercavition projectile is a kind of uncontrolled, unpowered underwater weapon, the formation and stability of cavitation are more significative for performing the properties of projectile. The paper has done same simulate calculation for a new designed subcaliber supercavitation projectile, focused on the cavitation morphology and drag reduction ability under several different projectile velocity circumstance. This research can provide same basis for reasonable structure design of new projectiles.

Abstract: The changes of the tip geometry due to the tip wear can completely alter the variation of the adhesion force dependence on the humidity. In this paper, we propose a simple method to calculate the width of tip wear using the adhesion force at inflection point of the experimental adhesion force versus humidity curves. Theoretical results show that the turning point of the adhesion versus humidity curve is closely correlated with the width of the worn tip, which can be precise calculated. The validity of the proposed method is proved by the agreement of our calculate results and the existing experimental data.

Abstract: The dynamic behavior of a simple beam suspended at the other end by an inclined cable is studied. In consideration of non-linear of the beam and the cable, the equations of the cable-stayed beam are obtained with the help of the lagrangian multiplier method. The ensuing ordinary differential equation has both quadratic and cubic terms, due to geometric nonlinearities and the non-linear coupling between the cable and the beam also. Meanwhile, the boundary and connection conditions are ensured by mechanics equilibrium condition. Then setting the determinant of the coefficient matrix equal to zero, the exact eigenvalues can be given. Following, the results of the parametric analysis on the in-plane and out-of-plane eigenproblems are presented.

Abstract: A nonlocal-gradient elasticity beam model with two independent gradient coefficients based on the classical nonlocal elasticity theory and strain gradient theory is used to study the pull-in instability of electrostatically actuated nanobeams. The numerical results show that the pull-in voltage of nanobeams are affected by the small scale. And the two independent gradient coefficients play the different roles in it. This paper broadens the way of studying scale effect.

Abstract: Currently, neither the efficiency nor the effectiveness is sufficient in the area of the assemble optimization that commonly involves the genetic algorithm. A novel method to solve the cumbersome problem in the optimization of assembly sequences was proposed. On the basis of the assembly constraint matrix, the optimized assembly sequence is obtained with the proposed evaluating factors of the process requirement. That is the evolution of the original genetic algorithm to a certain extent. The effectiveness of the proposed method was proved by the comparison with the ant colony algorithm.

Abstract: The structure and working principle on Spinner institutions of iron roughneck are introduced. The stress analysis on Spinner institutions is done according to the theory of mechanics and the load formula of the hydraulic cylinder is obtained. Spinner model is set up using professional three-dimensional design software: Inventor, and imported into the ADAMS for simulation analysis, the clamping force curve of spinner institutions and stress value of the key components are obtained. The article verified the correctness of the system and provided theoretical basis for the parameter setting of the system practical action and control.

Abstract: In the melt-blown nonwoven fabric technology,the design of melt blowing die drawing hot air passage is very important. The design of spinning die rely on mapping and experience currently,when forming the series are often inadequate design basis.In order to obtain the die flow of air jet flow and temperature distribution,this paper analyzes the working principle of the die head assembly and establish three basic equations of jet flow field; got jet flow field velocity profile and airflow temperature distribution,experimental results shows that airflow jet flow field simulation results by Fluent obtained are true and reliable,it can also provide references of similar design.

Abstract: This paper proposes a three-phase inspection policy model based on a three-stage failure process for a single unit system. Different from existing works which usually assume unique inspection interval, the three-phase inspection policy allows the inspection policy to change according to the identified state of the unit. The possible renewal scenarios are considered based on which the cost model is proposed. Numerical example is presented, and the results clearly reveal the advantage of the three-phase inspection policy over the unique interval inspection.

Abstract: In this paper the problems of traditional operation maintenance strategy is introduced. Uncertain multi-stage and multi-objective decision-making model of operation and maintenance is shown in this paper. Considering the life cycle cost, the best maintenance scheme is determined through the establishment of an uncertain multi-stage and multi-objective decision-making model of operation and maintenance. It also proves the practical applications of UMM model by GIS example.