Advanced Materials Research Vols. 295-297

Abstract: The prevention of fatigue failure is an important consideration in the design of aeroengine shafts. In this paper, based on the elastic and elstic-plastic finite element analyses, for a series of small-scale hollow shafts with transverse holes, the maximum princple stress and von Mises stresss around the hole have been obtained. Hence, using McDiarmid and Von Mises criteria, the fatigue crack initiation site and life can be determined. The hoop stress, which is the driving force for the Mode I growth of short cracks initiated around the hole, has been characterised as well.

Abstract: Composite materials (55 vol.% SiC_p/A356) were brazed by filling with a Zn-based alloy with the assistance of ultrasonic waves. 37 vol.% SiC particles composite bonds were produced and their structural features as well as mechanical properties were obtained. The crack initiation and propagation behavior of the composite bonds were examined using in situ SEM and SEM fractographic observations. The shear strength of the brazed bonds containing ~37 vol.% SiC particles was 37% higher than the 55%SiC_p/A356 composites and 48% higher than the un-reinforced bond. There are two mechanisms of crack initiation in metal matrix composite. In the first cracks may initiate at in the eutectic phase in the composite bond. In the second cracks may also initiate due to cracking of the particles.

Abstract: Beijing suffers a great road transport problems, including environment pollute, congestion, and etc. A research supported by the national basic research program of China to solve transport related environmental problems introduced an environmentally sustainable transport research framework. Results showed that the dramatic increasing of total vehicles was the key driving force. NO_x and CO₂ emitted by vehicles were two main pollutes that might touch the environmental capacity in 2020. Policy instruments were proposed to control the total vehicle, the NO_x emission and the CO₂ emission. The time arrangement of policy instruments was partly accepted by the local government. Continuous monitoring showed that the effects of the policy planning were mixed.

Abstract: A method to calculate the radiation sound power from the sound source characteristic of the duct component is developed here; The relationship between the sound source characteristic and the acoustical boundary conditions of the duct ends is also researched by the experiment. Based on the two-port model, the sound source characteristic and the sound transfer matrix of the duct component can be obtained by the numerical or experimental methods. The calculation model to predict the radiation sound power at the end of the duct system is deduced from the sound source characteristic of the duct component. A simple experimental duct system to validate the calculation model is setup and the measurement and calculation results are compared here as well.

Abstract: In order to investigate the effect of plasma nitriding treatment on fatigue behavior of titanium alloys, very high cycle fatigue tests were carried out for Ti-6Al-4V alloy using an ultrasonic fatigue machine under load control conditions for stress ratios of R=-1 at frequency of ƒ=20KHz. Experiment results showed that plasma nitriding treatment played the principal role in the internal fatigue crack initiation. More importantly, plasma nitriding treatment had a detrimental effect on fatigue properties of the investigated Ti-6Al-4V alloy, and the fatigue strength of material after plasma nitriding treatment appeared to be significantly reduced about 17% over the untreated material.

Abstract: A series of hydrosilyl-terminated polydimethyl-siloxane (HTP) of different molecular weight was cross-linked with 2,4,6,8-tetramethyl-2,4,6,8-tetravinyl-cyclotetra siloxane (D₄V) to afford a three dimension cross-link network. They were systematically synthesised through acid-catalyzed ring opening polymerization of octamethyl-cyclotetrasiloxane (D₄) followed by hydrosilylation reaction using Platinum complex catalyst. Chemical structure of HTP was characterized using FTIR and H-NMR. Mechanical properties were established using Shore A hardness which were closely related to the cross-link density.

Abstract: This paper adopt universal finite element calculation software to carry out force analysis for Shunqiao trench-buried inverted siphon，computer is applied in analysis of trench-buried inverted siphon. Deducing variation law of the inverted siphon’s stress and displacement in construction process and operational process. The calculation results Further shown design scheme’s Rationality and safety. which provide reliable reference of design and construction for the trench-buried inverted siphon.

Abstract: Three-dimensional digital oral treatment technology based on anatomical features of jaw bone and teeth was applied for modeling. Three dimensional finite element models for the restorative systems with straight glass fiber post, screw glass fiber post and one-piece glass fiber post-and-core were established. Stress and deformation under external bite force were calculated and compared among different post types. Comparing the maximum von Mises equivalent stress in the whole restorative system for the straight post, the screw post and the one-piece glass fiber post-and-core finds that the one-piece glass fiber post-and-core is effective to lower the maximum stress and obtain uniform stress distribution of the teeth. Even in each part of the restorative system like post, crown and root, the maximum stress in the case of one-piece glass fiber post-and-core is still lowest. Using one-piece glass fiber post-and-core, the overall deformation of the restorative system is decreased greatly.

Abstract: In this paper, the CAD/CAM of tooth profiles of DIN, BS, JIS S, and JIS U sprockets are investigated. In order to verify the process and investigate the efficiencies of the sprockets, an experimental test rig is set up to evaluate the efficiencies of different shapes of sprockets. Applying the theory of gearing and coordinate transformation, the mathematical models of DIN and BS types of sprocket are derived comparing with JIS S and U typed sprocket. The MasterCAM software is used to simulate the cutting process of sprocket. The manufactured sprockets are tested in the developed test rig to show the efficiencies of different types of sprockets. The algorithm developed in this paper can also be applied to study others new shapes of tooth profiles.

Abstract: In this paper, finite element simulative analysis is proceeded for reinforced concrete face rockfill dam of Qianqiao reservoir. Deducing variation law of the dam’s stress and displacement in construction process and operational process. The analytic results are shown：reinforced concrete face rockfill dam of Qianqiao reservoir is reasonable structure, and every index meets the requirements for design.