Applied Mechanics and Materials Vol. 431

Abstract: A probabilistic method to durability is proposed for the design of reinforced cover of a concrete immersed in marine environment. It uses a non-linear chloride diffusion model for a saturated medium. Parameter variability is estimated and used by the probabilistic method to assess the probability of reaching a critical chloride concentration near the reinforcement for a given service life. Based on the concrete formulation and the cement chemical composition, the model parameters are evaluated with their associated random distribution.

Abstract: This work investigated properties of diffusive magnetic particles. Random walk Monte Carlo method was used to simulate the Ising spin diffusing and flipping to examine the properties of the system. The Ising spins interact among themselves via Lennard-Jones interaction. Metropolis algorithm was employed to update spins configuration on the continuous space. The volume of Ising spins, magnetization and magnetic susceptibility, were investigated as functions of temperature, number of Ising spins in the system and simulation time. It was found that, at low temperatures, the Ising spins tend to stay close even at long simulation time, where finite magnetization was found suggesting the ferromagnetic preference. However, at high temperatures, paramagnetic behavior reveals as ferromagnetic interaction ceases with time passing. This is due to role of spin diffusing which causes the spins to disperse and hence ferromagnetic interaction among spins reduces.

Abstract: This work investigated the competition effect between the ferro-and antiferro-interaction on the domain size and domain interface in two-dimensional binary alloy. Monte Carlo simulation and Ising model were used to model the alloy system where largest domain size and the domain interface were observed to identify the low temperature ordered phase and the high temperature disordered phase. The simulation results show that domain size is maximized when the ferro-interaction is preferred, but domain interface becomes maximum instead when the antiferro-interaction is favored. These domain properties were reported as a function of temperature for various magnitude of ferro-and antiferro-interactions. In addition, the artificial neural network was used to create database of relationship among the ferro-and antiferro-interaction, the simulated temperature and the domain properties. Good agreement between the real targeted outputs and the predicted outputs was found, which confirm the learning-by-example ability of the artificial neural network. This work therefore presents another step in the understanding of how complex interaction plays its role in binary alloy problem and how a data mining technique assists development of understanding in materials science problems.

Abstract: The fractured drill pipe was investigated by means of non-destructive testing, chemical composition analysis, optical microscope, material property testing machine and SEM with EDS. The results showed that fracture of drill pipe body was hydrogen sulfide stress corrosion cracking. High strength, high hardness, and stress corrosion sensitivity of the drill pipe material were important reasons leading to failure.

Abstract: The traditional response estimation model is based on force-response relationship. According to the transmissibility concept in linear time invariant system, a new response estimation method-transmissibility function (TF) method is provided based on response-response relationship. First, the principle of the method is interpreted in mathematic formula and the restriction condition is presented. Then, an engineering technique called operational conditions combination is presented for calculating the transmissibility function (TF) of vibration responses, and the guideline on how to devise the scheme of working conditions is discussed. Finally, the performance of the developed transmissibility function method is validated by a cylindrical double-shell exciting experiment.

Abstract: Cyclic fatigue of rotary endodontic instruments has been tested using different techniques while the results were normally compared in terms of a canal curvature radius R and an angular extent of instrument insertion θ. In this work, the effects of canal geometry and analysis method have been investigated by finite element (FE) analysis. A highly simplified FE model has been proposed and verified experimentally. Results from a detailed finite element (FE) model and a simple geometric model are discussed in the light of the simplified model results. It was found that the commonly used (R, θ) alone cannot quantify the severity of bending. The diameters and taper development of the canal and the instrument also played important roles. The simple geometric model can give unacceptable errors and cannot only be employed forensically. The detailed finite element model is much more resource consuming than the current simplified model and the extra effort is not worthwhile if only the bending strain is needed for correlation and prediction of instrument fatigue life.

Abstract: Water cushion belt conveyor is a new type of continuous conveyor which develops from belt conveyor and air cushion belt conveyor .By experimental research on water cushion belt conveyor ,we can observe the condition of water cushion and accomplish the date acquisition of water cushion pressure .Analyzing the pressure ,we can get influencing factors of water cushion pressure and verify the feasibility of industrial application of water cushion belt conveyor .Combining theory study with experimental study ,provide theoretical basis and guide for the further progress of water cushion belt conveyor .

Abstract: Profile of the screw rotor comprised of varieties of curves is characterized by complexity and asymmetry. Determination of the billet diameter has a significant influence on the quality of the driven rotor formed by fixed cross rolling. Owing to this the general equation to determine the area of the complex tooth has been presented. Then detailed calculations of the spiral teeth volume and the sectional area of the driven rotor have been carried out. Satisfactory result that the relative error is less than 0.002% has been demonstrated by comparison of theoretical calculation and measurement result to verify the accuracy of the proposed theoretical calculation.

Abstract: A universal mathematical model for machining cycloid approximating involute and straight lines is developed in this study based on the definition and parameter-equation of cycloid and the machining principle of cycloid rotational indexing. The machining examples of the various parts are presented to show the feasibility of this model.

Abstract: In automotive industry, thin walled beam is widely used to build vehicles structure. Vehicle structure is built by joining thin walled beams using various welding techniques. The usage of thin walled structure in automotive is important to improve vehicle performance by offering better strength-to-weight ratio. However the application of thin walled structure will cause few drawbacks to vehicle structure. When thin walled beam or structure is loaded with compression load, at certain limit it will undergo local or global buckling. Another problem is when thin walled beam is joined to other thin walled beams, it will show unexpected deformation which called joint flexibility. Both phenomena will cause numerical and analytical model to predict stiffness of structure tend to deviate from experimental result. In vehicle structure fabrication 3D space frame is used a lot. As a case study for this application, area around car bulkhead where cross member, side sill and A pillar are connected to each other at right angle is studied. The intention of this research work is to produce validated finite element model to predict equivalent stiffness of 3D space frame structural joint. Finite element, shell element is most common technique used to model the joined structure. However it is known that shell model cannot produce good result. In this result work, modelling of equivalent stiffness for 3D space frame structural joint is presented. The result shows, using this model the accuracy is about 65%. New modelling technique is proposed to increase the accuracy based on solid model. By introducing circular beam elements at welding area, it is found that accuracy improves up to 90%.