Applied Mechanics and Materials Vol. 404

Abstract: Due to substantial loss of coronal tooth structure, corono-radicular stabilization is often required, especially in anterior teeth to provide retention and resistance form for the restoration. The use of ferrule as a part of the artificial crown was proposed in reinforcing the root-filled teeth. The purpose of this study was to investigate the effect of the ferrule height on stresses induced in an endodontically treated maxillary central incisor, which was restored with pressed ceramics, using numerical analysis. The study was developed for in order to obtain 3D models, for the design of the prepared teeth, pressed ceramics post and core systems and crowns. The use of ferrule as a part of the core was proposed in reinforcing and therefore six levels of the ferrule height were designed in order to be investigated. The study was performed on a central upper incisor, using a finite element analysis. Von Mises equivalent stresses were calculated and their distribution was plotted graphically. Regarding stress distribution in the crown high stresses are present cervical. In the prepared root stresses are under the finishing line and in the post cervical. In the post, with the increase of the ferrule height, the stresses move in coronal direction. No significant differences were found between the maximal stress values for the studied preparation designs (a ferrule height between 1 and 6mm).

Abstract: The application of the nanoparticle technology is more and more popular currently. For the excellent abilities, nanoparticle technology is widely used in the biotechnology research. Nanometer microspheres can be used as a drug carrier. But the blood viscosity has relatively greater influence on its flow performance. The flow characteristics of nanometer microspheres in the vessel is very important to the curative effect. In order to resolve this problem, a length of vessel is introduced. By the CFD(computational fluid dynamics) software, the diffusion flow phenomenon is studied. The computational result and the analysis show that the nanometer microspheres would mix rapidly around the corner of the vessel. The results may provide technical reference of the further research.

Abstract: FMEA(Failure Mode and Effects Analysis) for the tank truck tail bumper design is systematically performed. The results reveal that FMEA plays a significant role in the early stage of design to identify the weak links, and its considerably potential in improving the reliability of the product and the subsequent repair and maintenance procedure. In the process of new product development, the implement of FMEA tend to be increasingly intensive and completed, which provides a qualified guarantee for the industrialization of the new product.

Abstract: the elastic vibration control method of actively changing parameters of flexible manipulator arm which includes actively changing rigidity and damping is put forward in this paper . these two control methods which are the control method of actively changing rigidity through increasing axial tensile force and the control method of actively changing damping by increasing structural damping are analyzed , and the corresponding mechanical structure and drive control method are designed . Simulation calculation indicates the effectiveness of the control method.

Abstract: dynamic model of flexible manipulator arm having end position addition mass is deduced in the first place in this paper , then the state space expression and transfer function using drive moment as input and using elastic vibration of end position as output of flexible manipulator arm are obtained . the necessary and sufficient condition assuring stability of flexible manipulator arm system is obtained using Routh criterion , and the stability criterion of the elastic motion of end position is deduced . the influence of end position addition mass and drive joint rotary inertia on the elastic motion stability of end position of manipulator arm is analyzed based on the stability criterion .

Abstract: The drag reduction characteristic of air deflector of a heavy-duty vehicle is examined through CFD simulations and wind tunnel test in this paper. The CFD model of the truck is built using the FLUENT software and the simulation results are compared with the wind tunnel test data to verify the accuracy of simulation model. An air deflector is designed for this truck, A design of experiments approach was chosen as an efficient technique to optimize the design parameter and match with the truck to obtain the optimal drag reduction performance.

Abstract: This study was aimed to investigate the influence of the linear guide configuration on the dynamic characteristics of a gantry milling machine. To predict the dynamic characteristics, we created the finite element model of the gantry machine, in which linear components were also included and modeled with the introduction of the contact stiffness defined by Hertz contact theory. Using this model, the vibration modes dominating the dynamic stiffness were determined. The results of the finite element simulations reveal that the linear guides with different preloads greatly affect the dynamic responses of the spindle tool. These results were validated by performing vibration tests on the milling machine prototype. Comparisons of the predicted results and experimental data show good agreements between them. According to the analysis results, the maximum dynamic compliance can be increased by 33% in X-axis direction and decreased by 18% in Y-axis direction, respectively when the linear guides are changed from low to high preload. Overall, current results clearly suggest that the proposed gantry model can be used to evaluate how the specification of the linear components can affect the machining performance of the milling machine.

Abstract: Turbocharger is a device used for compression of gases of different features. I tis a conversion of kinetic energy or mechanical energy into pressure. Compressed media can be vary from pure gases such as hydrogen, oxygen, noble gases to the gas mixtures such as air, a mixture, of hydrogen and others. Gas composition is very important because of its physical and chemical properties depends on many parameters of compressor design [. The basis of modelling surge dynamics of centrifugal compressors is Greitzerov nonlinear model. This article is getting the gear characteristics of the mass flow and pressure increase passing compression system. Another challenge is getting the throttle characteristic mass flow and pressure drop on the throttling valve. These characteristics are necessary for modelling the dynamic model of a centrifugal compressor according Greitzer (1976). For getting these characteristics, it is necessary to know the data of the measurements. Data can be extracted from a manufacturer. One of the most important graphs is compressor characteristic, known as the compressor map.

Abstract: Temperature distributions of cold forging process for a cambolt has been predicted by using finite element method in this paper. The cambolt is used as a part in the steering system of a vehicle for the purpose of driving balanced, so some proper mechanical properties such as strength and endurance limit are required for this part. Moreover, temperature is also an important factor to realize mass production and improve efficiency. However, direct measurement of temperature in a forging process is infeasible with existing technology; therefore, there is a critical need for a new technique. In this study, the thermo-coupled finite element method has been presented for predicting the temperature distribution. The rate of the energy conversion to heat for the material of workpiece has been defined and the temperature distribution throughout the forging process of the cambolt has been analyzed. Experimental verification of the technique is presented.

Abstract: In order to provide a profitable and cost-effective way in maintaining a machine, it is necessary to prepare an economical way to provide service manipulation is to prepare standard and stable spare parts, replacements, and consumables in stock. The problem of accurate prediction of load, deformation and stresses in 3D contacts is then revisited. Most research has used one, two or three pairs of meshing teeth to simulate the mating process. It is insufficient to describe the entire process of three contact zones during each mating pair. By implementing a combined 3D face-contact and FEM, contact stress analysis between two spur gear teeth was considered in eleven different contact positions during a full mating process. The proposed approach provides a complete and effective solution of the contact problem in quasi-dynamic way. Instead of applying more fixed boundary conditions to constrain and simplify material behavior in 2D models, point and line contact of tooth surfaces are substituted by a face contact model of teeth in this article.