
محمدرضا
بهاری
author
بابک
مولایی
author
text
article
2003
per
University College of Engineering
دانشکده فنی
08031026
37
v.
1
no.
2003
https://jfe.ut.ac.ir/article_14375_2c25f8d471b9082afedf2aa19f675b55.pdf

محمدصادق
معرفت
author
شروان
عطایی
author
اسماعیل قهرمانی
گرگری
author
text
article
2003
per
To evaluate the remaining load carrying capacity of AkbarAbad Railway Bridge, dynamic and static load testing were carried out. The bridge included five identical 6meter arches, made of mass concrete material, with more than 60year old. In the dynamic test, a
120ton locomotive passed over the bridge at different speeds and displacements and accelerations were recorded at critical sections. In the static test, 500 tons of rail weight was gradually applied to the middle span and deflections were measured. The bridge showed a relatively stiff response without any indication of resonance or big dynamic magnification effects during the tests. The response remained linearelastic under maximum load and the results suggested a relatively large strength reserve, relative to the standard service loads, for the bridge. Overall, the study showed that, despite aging effects and experiencing deep and wide cracking at the crowns, the bridge still enjoyed relatively large strength reserve and safe performance.
University College of Engineering
دانشکده فنی
08031026
37
v.
1
no.
2003
https://jfe.ut.ac.ir/article_14376_9f028d39f205d8f26ea37179c70a34ba.pdf

محمدرضا ملکی
جوان
author
علی اصغر
میرقاسمی
author
text
article
2003
per
Discrete Element Method can be used for numerical analysis of different geotechnical problems such as retaining wall earth pressure distribution. This paper is an effort to use the method in determining active and passive earth pressure distribution behind a retaining wall. Soil mass in the present method is treated as comprising of blocks, which are connected by
elastoplastic Winkler springs. The solution of this method satisfies all equilibrium and compatibility conditions. The method has the simplicity of the classic limit analysis and offers more ability in solving problems in complex geometry and loading conditions such as seismic impacts, pore water pressure, nonhomogeneity of the soil reinforced backfill soils, etc. In this paper, the formulation of the method is briefly reviewed. Examples are shown to demonstrate the applicability of the method for analysis of earth pressure behind a retaining wall including dynamic lateral
pressure of nonhomogeneous soil. The results are compared with previous classic methods.
Applicability of OEM for analysis of reinforced soil structure and advantages of this method over conventional methods are also discussed.
University College of Engineering
دانشکده فنی
08031026
37
v.
1
no.
2003
https://jfe.ut.ac.ir/article_14377_a604bc43d9dded866786509476079d9e.pdf

اسداله
نورزاد
author
ناصر
دائیان
author
text
article
2003
per
Calculation of impedance function is a mixed boundary value problem, which is changed to a Neuman problem by using a functional expansion of stress distributions. The problem is, then, solved using integral transforms (Hankel transform for circular foundations) and the impedance function is obtained in terms of an integral that is resulted from Hankel inverse transform. This integral cannot be solved analytically and, therefore, is solved numerically and the impedance function is obtained. The variation of impedance function with dimensionless frequency is presented for some isotropic or transversely isotropic materials with different poisons ratios. It can be seen that anisotropy has a great effect on impedance functions and this effect increases as the anisotropy ratio increases.
University College of Engineering
دانشکده فنی
08031026
37
v.
1
no.
2003
https://jfe.ut.ac.ir/article_14378_dbfcfed9f940304292c2f5c0f0a166f6.pdf

محمود
نیکخواه
author
سید مجدالدین میرمحمد
حسینی
author
text
article
2003
per
University College of Engineering
دانشکده فنی
08031026
37
v.
1
no.
2003
https://jfe.ut.ac.ir/article_14379_6935aa22cf0f3372cd7ecc0a9321eb04.pdf

شهرام
وهدانی
author
کارولوکس
author
ایمان
کریمی
author
text
article
2003
per
Analysis of amplification of base motion passing through the V_shape valises, filled with alluviums, is usually involved with uncertain geometrical parameters and geotechnical properties. It is also involved with complex and time consuming soil structure interaction algorithms. Therefore, a neuro_fuzzy system can result in a reasonable solution avoiding any interaction analysis for a particular geometry and geotechnical
parameters. Defining such fuzzy system, of
course, needs a large number of interaction analyses, each, participating in training of the system. In this work, it is shown that a midpoint result namely; an amplification curve with respect to dimensionless frequency, exists, which can brake the procedure into two
parts, each using a small number of interaction analysis. The results of narrow valises are presented in two different ways: A verbal description type of results for quick reference, and a calculation method using any conventional fuzzy software.
University College of Engineering
دانشکده فنی
08031026
37
v.
1
no.
2003
https://jfe.ut.ac.ir/article_14380_ddefa13d6b357640568c1fb3ae3caebe.pdf

لیلا هاشمی
بنی
author
علی
عزیزی
author
محمدحسن هاشمی
بنی
author
فرهاد
صمدزادگان
author
text
article
2003
per
In this research work a shape from shading (SFS) technique which incorporates a Lambertian model is implemented for the automatic generation of a digital terrain model (DTM) using a single view aerial image. The developed algorithm is tested on both simulated and real data. The estimated accuracy of the generated DTM from the simulated data, which has a bilinear surface, is about :t3 cm'. The real data is a scanned aerial photograph taken over a low texture hilly terrain. The generated DTM by the SFS technique is compared with a DTM acquired by the manual measurement of the stereo image of the same area using a photogrammetric plotter. The estimated rimes of the discrepancies between the grid nodes of the measured and the automatically generated
DTM is about :t4 meters. The unsuccessful
reconstruction of the terrain surface for the real data is due to the fact that a simple Lambertian model does not take into account, in a perfect way,' different nondeterministic influential factors such as the terrain alb Edo variations and the random noise. The influence of the latter case was reduced by a low pass filter applied as a preprocessing stage.
University College of Engineering
دانشکده فنی
08031026
37
v.
1
no.
2003
https://jfe.ut.ac.ir/article_14381_23d0ec517b7fde76012381ead0724d7d.pdf

محمدرضا
اشراقی
author
دکتر ناصر
سلطانی
author
text
article
2003
per
The direct application of finite element method to crack problems will produce errors, which cannot be neglected. One of the major sources of the errors is crack tip singularity, The numerical solution of path independent JIntegral method is considered to be based on conservation law of energy in conservative fields. Combination of such method with finite element method creates a very powerful tool to analyze cracks with complex shapes and model geometries. In the present research after a short review of fracture mechanics history in general and JIntegral in particular, cracks in composite materials which are divided into internal cracks and interlaminar cracks are
analyzed using JIntegraI. For numerical solution of JIntegral two computer programs are written using MA TLAB software. Input data for these programs, stressstrains and coordinates of nodal points come from output files of finite element analysis. These programs
read their input data directly from the output files of finite element program. Comparison between results of the present study and existing results in literature shows the ability of this method in analyzing plane crack in threedimensional space.
University College of Engineering
دانشکده فنی
08031026
37
v.
1
no.
2003
https://jfe.ut.ac.ir/article_14382_a05266641e2ac0528abb9eec9171bd19.pdf

داریوش جواب
ور
author
غلامحسین
لیاقت
author
ابوالفضل
درویزه
author
امیر
عبدالله
author
text
article
2003
per
Explosive forming of cone was investigated from some new analytical, numerical, and experimental aspects. In the analytical modeling, it is supposed that deformation profile of plate is a truncated cone during process, which will be deformed to a fully formed cone at the end of process. The variation of plate thickness was also neglected. Analysis required equations for determining vertical velocity and vertical displacement profiles during process; required pressure and
final product dimensions are also given in this analytical model. ABAQUS/Explicit package
was used for FEM simulation. The results of analytical model given in this paper are fully agreed with experimental and numerical (FEM) results.
University College of Engineering
دانشکده فنی
08031026
37
v.
1
no.
2003
https://jfe.ut.ac.ir/article_14383_507fe5cf78507bf56ef7b4bbe2df8571.pdf

محمدسعید
سیف
author
ابراهیم امینی ماندی
محله
author
text
article
2003
per
In this paper relationships for resistance and trim of planing Catamarans in calm water are presented. This work is based on Savitsky empirical method for monohull planing crafts. According to the present method, a computer software is developed for calculation of resistance and trim of a Catamaran in different speeds. Moreover, the effects of different factors such as displacement, longitudinal center of gravity, deadrise angle, length to beam ratio, distance between demihulls are studied. The
investigation of these factors can be very
useful in preliminary design for designers and initial assessments of the craft
University College of Engineering
دانشکده فنی
08031026
37
v.
1
no.
2003
https://jfe.ut.ac.ir/article_14384_6e11634c3a76ab956b52c14dc6280f65.pdf

کیوان
صادقی
author
text
article
2003
per
The present work addresses the validity of noslip condition for waterbased bentonite drilling muds. The mud used for the investigation was a suspension of 10% solid (bentonite) concentration and its wall slip effects was explored using viscometric techniques. A concentriccylinder viscometer (model Fann SOC) was used for this purpose. Flow curves obtained using two bobs with different radii indicates that the viscosity measured is a function of the gap distance between the inner and outer cylinders confirming that slip has indeed occurred for this particular mud. A simple technique was
explained which enables correcting the flow curve for the slip effects thus resulting in true viscosity function for the test fluid. Experimental results obtained show that slip
velocity scales with wall shear stress inferring that for this particular fluid, wall slip effects are less sever as compared to other nonNewtonian fluids such as polymer melts and solutions.
University College of Engineering
دانشکده فنی
08031026
37
v.
1
no.
2003
https://jfe.ut.ac.ir/article_14385_19ee7b54f85d2a2e61ce4c5a981aa959.pdf

غلامحسین
لیاقت
author
مجتبی
صدیقی
author
حمیدرضا
داغیانی
author
علی علوی
نیا
author
text
article
2003
per
Honeycombs are used in many industries due to their individual properties such as energy absorption property. In this paper the "angle element" is introduced and its energy dissipation mechanisms under quasistatic loading is studied. The crushing load of honeycomb is calculated by energy method and describing Wierzbicki model for determining the mean crushing strength and half wavelength of folding of cell walls, a new model is presented which predicts better results than the Wierzbicki model. Based on this analysis the cell geometry has important role on mechanical behaviour of honeycomb structures; so that decreasing the cell size increases the mean crushing strength and decreases the half wavelength of folding. On
the other hand increasing the cell wall thickness increases these two parameters. The
results of the new model is in good agreement with available experimental data.
University College of Engineering
دانشکده فنی
08031026
37
v.
1
no.
2003
https://jfe.ut.ac.ir/article_14386_0b7468253dcaf54c0e986505eb614513.pdf

محمد محجوب
جهرمی
author
مرتضی تقی پور
گورابی
author
text
article
2003
per
An attempt, herein, is made to present a comprehensive solution of Jerk vs. ForceOptimalControl of active suspensions. The comparison is made for a 1/4 car model; however, the body acceleration and jerk are directly from the system Hamiltonian. Also, in both J.O.C. and F.O.c. solutions, the force actuator is used to implement the controller. The results show that a reduction of jerk and acceleration is obtained against a higher rattle space and tire deflection. The compromise/tradeoff can be managed by setting appropriate weights in the cost function.
University College of Engineering
دانشکده فنی
08031026
37
v.
1
no.
2003
https://jfe.ut.ac.ir/article_14387_e9f14461e13fd8681749d217908eba6f.pdf

محمد محجوب
جهرمی
author
هادی
فضلی
author
text
article
2003
per
PAM (Principle Axis Machining) is introduced as an effective way of milling free
form surfaces On 5axis machines. PAM matches the minimum principle curvature of
Toroidal end mill to the maximum principle curvature of the surface at the machined points via tool inclination in two directions. An investigation is made, herein, for comparison of surface roughness in milling with 3 end mills (flatbottom, ballnoise, and Toroidal). This is done, first, theoretically based on tool/surface geometry along and across feed directions, and then evaluated according to some typical test results.
University College of Engineering
دانشکده فنی
08031026
37
v.
1
no.
2003
https://jfe.ut.ac.ir/article_14388_fbd6aae8f5c4b55a0c7cad0b51e770f8.pdf

کیوان
صادقی
author
مهدی
شریفی
author
text
article
2003
per
Laminar twodimensional flow of a viscoelastic fluid of the "SecondOrder" type was investigated above a fixed rigid plate. Conventional boundary layer approximations
were invoked to simplify the equations of motion which incorporate several elastic terms in addition to the familiar inertia, viscous and pressure terms. The governing boundary layer equation was realized to be a PDF equation which was further transformed into a nonlinear fourthOrder ODE through the use of the concept of a stream function together with introducing a similarity variable. The xcoordinate could not be eliminated from this equation, and so only local similarity solutions
could be obtained for this flow field. Using a combination of finite difference and shooting methods, this equation was solved numerically for Deborah numbers as high as 1.0. The results showed that the wall shear stress scales with fluid's elasticity, increasing for higher values of fluid's elasticity. The boundary layer thickness was also found to decrease with an in crease in the elastic level of the fluid. Around a Deborah number of 0.4, velocity inside the boundary layer is predicted to exceed that
outside the layer, a prediction which awaits experimental verification.
University College of Engineering
دانشکده فنی
08031026
37
v.
1
no.
2003
https://jfe.ut.ac.ir/article_14389_1354af253fb38e27f0771c10708dceec.pdf