Advanced Materials Research Vols. 199-200

Abstract: In order to simply and accurately measure the realistic motion of balls in a ball bearing, a method called the static oblique coordinates is proposed to measure the 3D motion of balls in an angular contact ball bearing. This measuring method utilizes Hall elements as the sensors which are assembled on the side of outer race and cage of the ball bearing with magnetized balls. The voltage signals of the Hall sensors are collected online and applied to calculate and analyze the variation of magnetic axis of the magnetized ball, from which the 3D motion of the balls can be calculated. The basic principles and experiment method of the measuring method are illustrated. This method has simple structure without damaging the bearing, by which the bearing’s real motion can be studied consequently with a high precision. The magnetization and magnetic pole detection methods in this study effectively solved the problem of magnetized balls’ magnetism un-uniformity which causes the measure signal chaos.

Abstract: Time-dependent reliability sensitivity design is discussed based on time-dependent reliability model, combining reliability optimization design theory and time-dependent reliability sensitivity analysis method, a problem on time-dependent reliability-based robust optimization design of components structure is studied, and a numerical method for reliability-based robust optimization design is also presented. The time-dependent reliability sensitivity is added to the reliability-based optimization design model and the reliability-based robust optimization design is described as a multi-objection optimization.

Abstract: Fatigue is one of the most common failure mode in hydraulic excavator boom. To find the most fatigue dangerous operating state of boom and effectively improve the life of the structure, a new method is proposed for the estimation of fatigue life under all operation states. In the case of unknown the history of loading, firstly find out the hinged support force under all boom poses, then calculate the stress of every point of the boom under the actions of each group hinged support force via finite element method, and finally simulate all operating states through the poses combination, conducts analysis of multiaxial fatigue life in the maximum principal stress as the nominal stress, calculates the life and the most dangerous operating state in all points, and compares to obtain the most dangerous position and the life of the boom. The results of contrast analysis showed that: the most dangerous zone of the excavator boom calculated by the life estimation method of all operating states coincide with the actual destruction situation. The life of the structure can be greatly improved after a simple reasonable improvement of the parts.

Abstract: The rapid growth of municipal solid waste (MSW) brings huge social and environmental pressures to our country, the treatment method of making garbage reduction, hazard-free and reclamation is accord with environmental protection and continuable development, and the key question of achieving this goal is to sort the garbage reasonably. On the basis of analyzing the characteristics of garbage, a new kind of roller-type urban living garbage sorting equipment was developed based on a special movement principle of cam mechanism proposed in this paper. This equipment can realize its function through a fixed cam axis, more than eighty sets of garbage separating needle assemblies reasonably distributed on the roller, in which needles (followers) can move in and out of the roller, and an active roller which rotates around the cam axis together with the needle assembles. As the core components of the equipment, cam mechanism and separating needle assembly was designed in detail, including the cam contour curve and force analysis, and the distribution of stress and strain of separating needles was obtained by using ANSYS software because it is the most easily damaged link in this equipment. The roller-type garbage sorting equipment can be used in the middle stage of garbage separation process to sort easily hooking garbage such as plastic, with higher separation speed and efficiency. It makes a good preparation for subsequent garbage separation work to improve the efficiency of comprehensive utilization of resources.

Abstract: The design of the fast flood discharge equipment structure with displacement reached 0.5×10⁴m³/h is given, which is based on the researchs of elimination methods for floods which happen in each kind of small reservoir in the flood season. This paper analyzes the equipment’s performance characteristic and application in the emergency on the spot. It indicates that its structure is reasonable and the performance is good.

Abstract: Reliability of equipment has long been considered as an important quality characteristic. Traditional methods of equipment reliability assessment are based on lifetime data. With equipment being much more reliable and the growing need for developing new equipments within shorter period and at lower cost, we can hardly get enough lifetime data in many cases. Performance degradation data can also be used for reliability assessment. This paper is mainly researched on reliability of a certain diesel engine. Through analyzing the failure mode and failure mechanism, performance degradation parameters of the diesel engine is selected as compression pressure in a cylinder while driven by an electrical motor. Based on a long time accumulation on performance degradation data, two methods of degradation path fitting and degradation value distribution are tried in this paper to evaluate reliability of the diesel engine. Besides, the regulation of the reliability variation is given by the results of the assessment.

Abstract: The variation rules of strength, load, and reliability of mechanical components are studied with a change in time, and a model is established for dynamic reliability of mechanical components under the random load acting. By combining the theory of reliability design with the method of sensitivity analysis, the computational method of dynamic reliability sensitivity design with arbitrary distribution parameter is proposed based on the methods Edgeworth and perturbation, and the problem of dynamic reliability sensitivity design of mechanical components distributed arbitrary distribution is solved as well as the variation rules of dynamic reliability sensitivity are given. The variation of reliability is studied as design parameters change a little, which provides theoretical data for dynamic reliability design of mechanical components.

Abstract: In view of which the state of equipment cannot be obtained accurately in real-time, a new method of state evaluation is proposed in this paper. Through Fault Tree Analysis (FTA) and Failure Mode Effects and Criticality Analysis (FMECA), the impact of parameters on equipment state is researched and the deviation is defined to quantify the variation of the state of equipment. The evaluating model based on deviation is established and illustrated with an example. The studied case is about the state evaluation for rotor blade and the application proves the method to be effective in the state evaluation for power plant equipment.

Abstract: We present a new response surface based stochastic finite element method to obtain solutions for general random uncertainty problems using the polynomial chaos expansion. The approach is general but here a typical elastostatics example only with the random field of Young's modulus is presented to illustrate the stress analysis, and computational comparison with the traditional polynomial expansion approach is also performed. It shows that the results of the polynomial chaos expansion are improved compared with that of the second polynomial expansion method.

Abstract: In an automobile, a stable and durable alternator is extremely important. Based on the basic characteristics of the alternators now on the mainstream market, the hardware simulation method was used to build a simulated “car engine-alternator-auto load-the external environment hardware environment” system. High and low temperature humidity test chamber simulates the vehicle internal environment and the inverter driving power frequency conversion is used to simulate motor car engine power system. It uses fixtures, belts, and pulleys to simulate the connection of the engine to the alternator. In addition it uses electronic load cases to simulate automobile electric power consumption with all kinds of current, voltage, speed signal components to provide feedback signals based on the testing system of alternator to make comparisons. The testing system is designed by analyzing and optimizing the structural mechanics of the whole system according to the requirement of the hardware system layout. For each part of the system factors of design were considered included shape, size, material selection process and heat treatment. Parts and detailed drawings were prepared and later sent for fabrication. The tests indicate that hardware alternator testing system has no major defects that can prevent it from being developed for commercial use.