توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Entropy generation : a basis to investigate the effect of preheating on residual stresses in weldments
نویسنده(ها): ، ،
اطلاعات انتشار: هفدهمین کنفرانس سالانه مهندسی مکانیک، سال
تعداد صفحات: ۵
The residual stresses produced due to violent thermal gradients in welded plates, cause significant problems such as brittle and fatigue fracturing. Several methods are suggested for reducing the residual stresses and undesirable deformations.<\div>

۲An Investigation of the Effect of Coolants on Residual Stresses in Weldments Based on Entropy Generation
نویسنده(ها): ، ،
اطلاعات انتشار: هجدهمین کنفرانس سالانه مهندسی مکانیک، سال
تعداد صفحات: ۶
How to cool the weldments is the one of the important input parameters to control the welding process and achieve a safe design. Generally, several coolants can be used for this aim. However, air and water that have been studied in this paper not only have too many practical applications but also will be examined as representative coolants. Heat transfer analysis based on convection coefficients, is one of the best method to investigate the effect of these coolants on induced residual stresses behavior. To fulfill this, in the present work, entropy generation has been introduced as a tool to predict the distribution of residuals tresses qualitatively. To check the application of the proposed method, a 3D numerical model is employed to study the similar behavior of residual stresses and entropy generation due to variation of different Heat transfer coefficients. Furthermore, the effect of convection coefficients on residual stresses and entropy generation has been investigated for both free and forced convections. Based on the present method's results, one can find that the behavior of entropy generation and residual stresses distribution with respect to different convection coefficients are very similar. Finally, the application of entropy generation minimization is checked in looking for the range of a satisfactory design in welding.<\div>

۳STATE–OF–THE–ART REVIEW ON FAULT CROSSING BURIED PIPELINE ANALYSIS
نویسنده(ها): ، ،
اطلاعات انتشار: ششمین کنفرانس بین المللی زلزله شناسی و مهندسی زلزله، سال
تعداد صفحات: ۹
one of the most important seismic havards on buried pipline systems is damages due to effects of fault movement s on pipelines which cross them . According to wide spread of pipelines and consequent high probability of this phenomena , analysis of pipelines in such a situation is one of the most important aims of researchers who are studying onpipeline systems seismic performance.<\div>

۴MICROTREMOR AND SHEAR WAVE VELOCITY MEASUREMENTS IN TABRIZ TO USE IN SEISMIC MICROZONATION
نویسنده(ها): ، ، ،
اطلاعات انتشار: ششمین کنفرانس بین المللی زلزله شناسی و مهندسی زلزله، سال
تعداد صفحات: ۸
To investigate the effect of soil conditions in different parts of the city, a number of 21 stations were selected for measuring microtremors and the shear wave velocities. The Fourier analysis, based on the H\V spectral ratio (H :Horizontal and V :Vertical), was made and the natural period of the ground surface at each site was determined by geometric average of the two spectra of EW and NS directions. For shear wave velocity measurements, a data logger accompanied with 3 geophones were used and waves generated by hitting a hammer were recorded and shear wave velocity and then the natural period of ground surface determined using calculations of refraction wave survey method. The natural periods of the ground surface determined by the two methods of microtremor measurements and refraction wave survey at the 21 stations are compared with each other and with results of a research done before in Tabriz city. The comparisons clarify accuracy of shear wave velocity measurements but not good results from microtremors because of noises inserted in these tremors.<\div>

۵MICROTREMOR MEASUREMENTS ON ARG–E TABRIZ (TABRIZ CITADEL) TO GET ITS DYNAMIC CHARACTERISTICS
نویسنده(ها): ، ، ،
اطلاعات انتشار: ششمین کنفرانس بین المللی زلزله شناسی و مهندسی زلزله، سال
تعداد صفحات: ۶
Arg –e Tabriz is a huge masonry structure which has been built in 14th century in Tabriz, Iran. At the time being, the remains of this building are only three huge brick walls arranged in U shape. The height of the building is 33 m and its length in web side is about 50 m and width along flange walls is about 20 m. The average thickness of the walls is 10 m. To study seismic assessment of the building, microtremor measurements were performed to estimate its dynamic characteristics and its site ground. Total number of measurement locations was chosen as ten; and totally twenty one components were recorded at the ground surface, basement, 1st floor and top of the building. The tests resulted in that the natural frequency of the building is 2.6 Hz in the both EW and NS directions. The natural frequency of the ground subsurface was also estimated by using H\V spectral ratio (H: Horizontal and V: Vertical) and obtained as 5.0 Hz.<\div>

۶ESTIMATION OF STRONG GROUND MOTION FOR NORTH TABRIZ FAULT USING STOCHASTIC GREEN’S FUNCTION METHOD
نویسنده(ها): ، ، ،
اطلاعات انتشار: ششمین کنفرانس بین المللی زلزله شناسی و مهندسی زلزله، سال
تعداد صفحات: ۸
Strong ground motions from future large earthquake are estimated at the historic masonry building, Bazaar, in Tabriz to examine earthquake–resisting capacity of the building in this paper. It’s very important to predict strong ground motions, estimate seismic damage and conduct retrofitting for a future large earthquake. Tabriz Bazaar is a brick structure constructed on about A.D.1400 or A.D.1500 and recently registered as the UNESCO World Heritage by effort of the state government. The stochastic Green’s function method is adopted to estimate strong ground motions at a target site. The target fault is North Tabriz Fault and the fault parameters, such as magnitude, seismic moment, stress drop, asperity size etc., are given by the recipe for predicting strong ground motions from future large earthquakes. Peak ground accelerations of the estimated strong ground motions for some rupture scenarios are in the range from 350cm\s\s to 800cm\s\s. The response spectra of estimated motions for some rupture scenarios are larger than that of observed records at Bam during the 2003 Bam Earthquake in the period range from 0.3second to 1.0second. The estimated strong ground motions will be very useful to examine earthquake–resisting capacity of the historic building, Bazaar, in Tabriz<\div>

۷simulation of crack growth behavior in residual stress field of welding
نویسنده(ها): ،
اطلاعات انتشار: کنگره بین المللی جوش و روشهای اتصال، سال
تعداد صفحات: ۱۰
the residual stresses generated due to welding in pressure components may have several harmful effects such as decrease in the resistance to cycling load and corrosive environments in this projects the element interaction technique for simulation of welding process for inconel 600 and A285 grade C steel by the help of ABAQUS software and fortran programing language is used in this technique the elements of the weld pool are held in place in contact with the elements of the base plate and the interaction is made to be a function of time this gave several flexibilities in modeling the welding process the simulation of welding of inconel 600 material is only used for verification of our written user subroutines by comparison with other works the predicted residual stresses for A 285 grade C were then considered in stress intensity factor calculations using a three dimensional finite element alternating model FEAM for investigating crack growth behavior for small elliptical surface cracks.<\div>

۸Prediction and analyze of microstructure of DP steels produced by controlled rolling process using neural network
نویسنده(ها): ،
اطلاعات انتشار: دوازدهمین کنفرانس ملی مهندسی ساخت و تولید ایران، سال
تعداد صفحات: ۶
In this study, the effect of controlled rolling parameters: reheat temperature, finishing temperature, finishing pass strain, interval time between final pass and quenching, quenching temperature and cooling rate on microstructure: ferrite grain size, martensite volume fraction and martensite hardness of dual phase (DP) steels with niobium were investigated. Microstructure parameters have been correlated with the rolling parameters and are brought out in the form of regression equations and 3D diagrams. The validity of the equations was checked by selecting random experiments in the range of variation of available data. Results show that the equations can predict the properties within the range of variation of the variables. Also, a neural network model was used to predict mechanical. The results of this investigation show that there is a good agreement between experimental and predicted values.<\div>

۹Investigating the effect of the interface in numerical calculation of mechanical behavior of dual phase steels by using micromechanical modeling cells
نویسنده(ها): ، ،
اطلاعات انتشار: کنفرانس دو سالانه بین المللی مکانیک جامدات تجربی، سال
تعداد صفحات: ۶
Dual phase (DP) steels have a fine microstructure consisted of martensite islands, dispersed in a ferrite matrix. Due to high strength along with high work hardening rate and ductility, this group of steels has received an extreme attention. In the present work, the effect of presence of the interface between ferrite and martensite in numerical simulation of the mechanical behavior of dual phase steels such as yield stress and tensile strength is studied. As the first step, dual phase steels with different volume fractions of martensite (Vm) are produced by various heat treatment procedures on low carbon steel and tensile tests are conducted on the produced specimens in order to determine their mechanical behavior. As the second step, a numerical investigation, based on a micromechanical model, is developed to capture the mechanical behavior of DP steels. ABAQUS finite element package is used in the numerical simulations. This investigation has considered the presence of constituting phase interface by taking advantage of Cohesive Zone Elements in the finite element software. In the numerical simulations, each phase has considered as an elastic–plastic solid. The obtained results show that the interface has a significant effect on the tensile behavior of DP steels and there is a good agreement between cohesive model and the experimental data.<\div>
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