Papers by Keyword: Mechanic

Abstract: This paper presents the results obtained by the authors when applying mechanical test methods that are validated using fatigue testing under simulated regime with finite element analysis. In addition to the mostly mandatory physical tests, the simulated regime testing can validate emerging conclusions. Virtual testing conclusions (computer simulated via Cosmos finite element analysis software), strengthen, complement and increase the accuracy of physical test conclusions. During the investigation of the physical test results, there are cases where the simulated physical test is not always explainable. This paper presents a case study conducted on special constructed screws that are subjected to fatigue and verified using the finite element analysis. It presents the possibility for practical application of simulated tests in order to redesign structures that fail during physical tests.

Abstract: It was tested the strength and wear value of recycled aggregate concrete mixing fly ash, slag, silica fume and double-mixture or three-mixture in deferent age. The results show that the wear value of recycled aggregate concrete mixing 30% fly ash is more than reference concrete at 3days, but can improve final wear-resisting property significantly. The wear value of recycled aggregate concrete mixing 30% double-mixture of fly ash and silica fume is much lower than reference concrete at 3days, and improve early wear-resisting property significantly. The flexural strength of the concrete is 4.26MPa at 3days, which can satisfy the traffic requirement. The wear value of recycled aggregate concrete mixing 30% three-mixture of fly ash, slag and silica fume is lower than reference concrete at 3days, but the declining rate is not significant. It investigates mechanics of double-mixture technique which improves wear-resisting property at the same time.

Abstract: Combined with the uplift static load test of large-diameter steel pipe pile in Xiangshan Port bridge of Ningbo, make analysis of Q-s curve and s-lgt curve, axial force distribution curve and unit shaft resistance, revealing the uplift characteristic of the steel pipe pile. The analyses show that the uplift steel pipe pile is pure friction pile, the uplift load is decreased downward through the axial force of pile body, the shaft resistance gradually plays from top to bottom and play completely in the upper soil. Moreover, it has used hyperbolic model to fit the measured Q-s curve by Matlab software, and the fitting precision is high. Then make the hyperbolic model non-dimensional, and attempt to predict ultimate bearing capacity using the maximum curvature point of the non-dimensional hyperbolic model, to get some mechanical characteristic.

Abstract: Four kinds of tri-axial shear structural yield stress is studied by controlling the pre-test consolidate degree and draining condition during the test. The results showed that draining condition influenced the tri-axial shear structural yield stress. When under the UU condition, structural characteristics appeared not clearly; when consolidated before testing and un-drained during test, only the undisturbed soil performed the structural yield stress; when draining during testing, the undisturbed soil showed the increased structural yield stress while the remolded soil could form certain structure. The impact of the draining condition on the structural characteristics is incurred by the change of the internal structure, which means that the draining condition have changed the arrangement and connection of the soil particles, then changed the soil structural properties.

Abstract: In steeply dipping working face rock movement, failure characteristics and distribution law of abutment pressure obviously affects seam mining. This paper takes the long wall for large inclined angle fully mechanized face of coal mine as the project background. The theoretical analysis and numerical simulation are adopted to study the break mechanism of the rock layer in steeply dipping seam mining; Through the numerical simulation results shows that the basic features are obtained, which are the biggest stress coefficient, abutment pressure of plastic area, roof weighting step，and convergence between roof and floor in working face．Based on the pressure appearance of the steeply dipping seam mining, control technology is given for the working face support stability, the work equipment prevent tumble and glide，and adjacent rock in the period of pressure. The study has a practice meaning in reducing coal mining accidents and improving the safety in steeply dipping seam mining.

Abstract: Mechanics is a comprehensive undergraduate major with multidisciplinary combinations among modern design and manufacturing technology, computer science, electronics, cybernetics, informatics, and modern management.This paper makes an investigation of the job hunting status and employment status of graduates major in Mechanics, proposing countermeasures and suggestions for specialty construction, enhancement of the quality of employment services, and strengthening of employment guidance.

Abstract: It is a great challenge to plan motion for humanoid robots in complex environments especially when the terrain is cluttered and discrete. To address this problem, a novel method is proposed in this paper by planning the gait according to the stance sequence and ZMP (Zero Moment Point) reference. It consists of two components: an adaptive footstep planner and a walking pattern generator. The adaptive footstep planner can generate the stance path according to the walking rules and adjust the orientation of body relevantly. As the footstep locations are determined, Linear Inverted Pendulum Model (LIPM) is used to generate the walking pattern with a moving ZMP reference. As demonstrated in experiments on the humanoid robot HOAP-2, our method can successfully plan footstep trajectories as well as generate the stable and natural-looking gait in typical cluttered and discrete environments.

Abstract: The present contribution gives an overview on own research that has been performed from 2008 to 2011 in Area 2, Mechanics and Model Based Control, of the COMET K2 Austrian Center of Competence in Mechatronics (ACCM), which is situated at the Science Park of the Johannes Kepler University of Linz. Area 2 is motivated by the fact that mechanics and control both are rapidly expanding scientific fields, which share demanding mathematical and/or system-theoretic formulations and methods. The goal of Area 2 has been to utilize and extend these relations, with special emphasis on solid mechanics and control methods based on physical models. Some corresponding results will be reviewed subsequently with respect to the mechanical modelling of structures, robots and machines, and with respect to the corresponding model based control as linear/non-linear lumped/distributed parameter systems. Due to limitations in space, the present review restricts itself to work of Area 2 that has been directly performed at the University of Linz. The review contains 118 references to works on mechanics and model based control.

Abstract: The infusion increase mechanism of power ultrasound on coal seam water infusion and its prospect of application are introduced. The research results show that: the main mechanism of power ultrasound to coal and water are mechanics and cavitations function. The porosity and permeability of coal can be improved due to the power ultrasound, so the speed of the water into the coal is improved. The technology of power ultrasound on the coal seam water infusion has a good application prospect.

Abstract: Along with the development of the science and technology and the change of the views of aesthetics, many novel machine structures appear, at the same time, the compatibility and the paradoxicality between the mechanics and aesthetics are placed before the machine designers. In order to improve mechanical properties of strength and stiffness in designing mechanical structure is easy to fall into misunderstanding that to improve mechanical properties depends on increasing outline dimension and the thickness of materials or selecting high performance materials. Elephantine shape, confusing alignment, incorrect size proportion and grave hue are the results of it. It is just enough to meet mechanical requirements but not ideal for aesthetic effect, increasing the cost. Conversely, it is not advisable to pursue beauty excessively or to make structure stress irrationally. This paper analysis on the harmony and contradiction between the mechanics and aesthetics of the machine, and puts forward some main measures for solving the contradiction.